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|
| -\input texinfo @c -*- texinfo -*-
|
| -@setfilename gdbint.info
|
| -@include gdb-cfg.texi
|
| -@settitle @value{GDBN} Internals
|
| -@setchapternewpage off
|
| -@dircategory Software development
|
| -@direntry
|
| -* Gdb-Internals: (gdbint). The GNU debugger's internals.
|
| -@end direntry
|
| -
|
| -@copying
|
| -Copyright @copyright{} 1990-1994, 1996, 1998-2006, 2008-2012 Free
|
| -Software Foundation, Inc.
|
| -Contributed by Cygnus Solutions. Written by John Gilmore.
|
| -Second Edition by Stan Shebs.
|
| -
|
| -Permission is granted to copy, distribute and/or modify this document
|
| -under the terms of the GNU Free Documentation License, Version 1.3 or
|
| -any later version published by the Free Software Foundation; with no
|
| -Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
|
| -Texts. A copy of the license is included in the section entitled ``GNU
|
| -Free Documentation License''.
|
| -@end copying
|
| -
|
| -@ifnottex
|
| -This file documents the internals of the GNU debugger @value{GDBN}.
|
| -
|
| -@insertcopying
|
| -@end ifnottex
|
| -
|
| -@syncodeindex vr fn
|
| -
|
| -@titlepage
|
| -@title @value{GDBN} Internals
|
| -@subtitle A guide to the internals of the GNU debugger
|
| -@author John Gilmore
|
| -@author Cygnus Solutions
|
| -@author Second Edition:
|
| -@author Stan Shebs
|
| -@author Cygnus Solutions
|
| -@page
|
| -@tex
|
| -\def\$#1${{#1}} % Kluge: collect RCS revision info without $...$
|
| -\xdef\manvers{\$Revision$} % For use in headers, footers too
|
| -{\parskip=0pt
|
| -\hfill Cygnus Solutions\par
|
| -\hfill \manvers\par
|
| -\hfill \TeX{}info \texinfoversion\par
|
| -}
|
| -@end tex
|
| -
|
| -@vskip 0pt plus 1filll
|
| -@insertcopying
|
| -@end titlepage
|
| -
|
| -@contents
|
| -
|
| -@node Top
|
| -@c Perhaps this should be the title of the document (but only for info,
|
| -@c not for TeX). Existing GNU manuals seem inconsistent on this point.
|
| -@top Scope of this Document
|
| -
|
| -This document documents the internals of the GNU debugger, @value{GDBN}. It
|
| -includes description of @value{GDBN}'s key algorithms and operations, as well
|
| -as the mechanisms that adapt @value{GDBN} to specific hosts and targets.
|
| -
|
| -@menu
|
| -* Summary::
|
| -* Overall Structure::
|
| -* Algorithms::
|
| -* User Interface::
|
| -* libgdb::
|
| -* Values::
|
| -* Stack Frames::
|
| -* Symbol Handling::
|
| -* Language Support::
|
| -* Host Definition::
|
| -* Target Architecture Definition::
|
| -* Target Descriptions::
|
| -* Target Vector Definition::
|
| -* Native Debugging::
|
| -* Support Libraries::
|
| -* Coding Standards::
|
| -* Misc Guidelines::
|
| -* Porting GDB::
|
| -* Versions and Branches::
|
| -* Start of New Year Procedure::
|
| -* Releasing GDB::
|
| -* Testsuite::
|
| -* Hints::
|
| -
|
| -* GDB Observers:: @value{GDBN} Currently available observers
|
| -* GNU Free Documentation License:: The license for this documentation
|
| -* Concept Index::
|
| -* Function and Variable Index::
|
| -@end menu
|
| -
|
| -@node Summary
|
| -@chapter Summary
|
| -
|
| -@menu
|
| -* Requirements::
|
| -* Contributors::
|
| -@end menu
|
| -
|
| -@node Requirements
|
| -@section Requirements
|
| -@cindex requirements for @value{GDBN}
|
| -
|
| -Before diving into the internals, you should understand the formal
|
| -requirements and other expectations for @value{GDBN}. Although some
|
| -of these may seem obvious, there have been proposals for @value{GDBN}
|
| -that have run counter to these requirements.
|
| -
|
| -First of all, @value{GDBN} is a debugger. It's not designed to be a
|
| -front panel for embedded systems. It's not a text editor. It's not a
|
| -shell. It's not a programming environment.
|
| -
|
| -@value{GDBN} is an interactive tool. Although a batch mode is
|
| -available, @value{GDBN}'s primary role is to interact with a human
|
| -programmer.
|
| -
|
| -@value{GDBN} should be responsive to the user. A programmer hot on
|
| -the trail of a nasty bug, and operating under a looming deadline, is
|
| -going to be very impatient of everything, including the response time
|
| -to debugger commands.
|
| -
|
| -@value{GDBN} should be relatively permissive, such as for expressions.
|
| -While the compiler should be picky (or have the option to be made
|
| -picky), since source code lives for a long time usually, the
|
| -programmer doing debugging shouldn't be spending time figuring out to
|
| -mollify the debugger.
|
| -
|
| -@value{GDBN} will be called upon to deal with really large programs.
|
| -Executable sizes of 50 to 100 megabytes occur regularly, and we've
|
| -heard reports of programs approaching 1 gigabyte in size.
|
| -
|
| -@value{GDBN} should be able to run everywhere. No other debugger is
|
| -available for even half as many configurations as @value{GDBN}
|
| -supports.
|
| -
|
| -@node Contributors
|
| -@section Contributors
|
| -
|
| -The first edition of this document was written by John Gilmore of
|
| -Cygnus Solutions. The current second edition was written by Stan Shebs
|
| -of Cygnus Solutions, who continues to update the manual.
|
| -
|
| -Over the years, many others have made additions and changes to this
|
| -document. This section attempts to record the significant contributors
|
| -to that effort. One of the virtues of free software is that everyone
|
| -is free to contribute to it; with regret, we cannot actually
|
| -acknowledge everyone here.
|
| -
|
| -@quotation
|
| -@emph{Plea:} This section has only been added relatively recently (four
|
| -years after publication of the second edition). Additions to this
|
| -section are particularly welcome. If you or your friends (or enemies,
|
| -to be evenhanded) have been unfairly omitted from this list, we would
|
| -like to add your names!
|
| -@end quotation
|
| -
|
| -A document such as this relies on being kept up to date by numerous
|
| -small updates by contributing engineers as they make changes to the
|
| -code base. The file @file{ChangeLog} in the @value{GDBN} distribution
|
| -approximates a blow-by-blow account. The most prolific contributors to
|
| -this important, but low profile task are Andrew Cagney (responsible
|
| -for over half the entries), Daniel Jacobowitz, Mark Kettenis, Jim
|
| -Blandy and Eli Zaretskii.
|
| -
|
| -Eli Zaretskii and Daniel Jacobowitz wrote the sections documenting
|
| -watchpoints.
|
| -
|
| -Jeremy Bennett updated the sections on initializing a new architecture
|
| -and register representation, and added the section on Frame Interpretation.
|
| -
|
| -
|
| -@node Overall Structure
|
| -
|
| -@chapter Overall Structure
|
| -
|
| -@value{GDBN} consists of three major subsystems: user interface,
|
| -symbol handling (the @dfn{symbol side}), and target system handling (the
|
| -@dfn{target side}).
|
| -
|
| -The user interface consists of several actual interfaces, plus
|
| -supporting code.
|
| -
|
| -The symbol side consists of object file readers, debugging info
|
| -interpreters, symbol table management, source language expression
|
| -parsing, type and value printing.
|
| -
|
| -The target side consists of execution control, stack frame analysis, and
|
| -physical target manipulation.
|
| -
|
| -The target side/symbol side division is not formal, and there are a
|
| -number of exceptions. For instance, core file support involves symbolic
|
| -elements (the basic core file reader is in BFD) and target elements (it
|
| -supplies the contents of memory and the values of registers). Instead,
|
| -this division is useful for understanding how the minor subsystems
|
| -should fit together.
|
| -
|
| -@section The Symbol Side
|
| -
|
| -The symbolic side of @value{GDBN} can be thought of as ``everything
|
| -you can do in @value{GDBN} without having a live program running''.
|
| -For instance, you can look at the types of variables, and evaluate
|
| -many kinds of expressions.
|
| -
|
| -@section The Target Side
|
| -
|
| -The target side of @value{GDBN} is the ``bits and bytes manipulator''.
|
| -Although it may make reference to symbolic info here and there, most
|
| -of the target side will run with only a stripped executable
|
| -available---or even no executable at all, in remote debugging cases.
|
| -
|
| -Operations such as disassembly, stack frame crawls, and register
|
| -display, are able to work with no symbolic info at all. In some cases,
|
| -such as disassembly, @value{GDBN} will use symbolic info to present addresses
|
| -relative to symbols rather than as raw numbers, but it will work either
|
| -way.
|
| -
|
| -@section Configurations
|
| -
|
| -@cindex host
|
| -@cindex target
|
| -@dfn{Host} refers to attributes of the system where @value{GDBN} runs.
|
| -@dfn{Target} refers to the system where the program being debugged
|
| -executes. In most cases they are the same machine, in which case a
|
| -third type of @dfn{Native} attributes come into play.
|
| -
|
| -Defines and include files needed to build on the host are host
|
| -support. Examples are tty support, system defined types, host byte
|
| -order, host float format. These are all calculated by @code{autoconf}
|
| -when the debugger is built.
|
| -
|
| -Defines and information needed to handle the target format are target
|
| -dependent. Examples are the stack frame format, instruction set,
|
| -breakpoint instruction, registers, and how to set up and tear down the stack
|
| -to call a function.
|
| -
|
| -Information that is only needed when the host and target are the same,
|
| -is native dependent. One example is Unix child process support; if the
|
| -host and target are not the same, calling @code{fork} to start the target
|
| -process is a bad idea. The various macros needed for finding the
|
| -registers in the @code{upage}, running @code{ptrace}, and such are all
|
| -in the native-dependent files.
|
| -
|
| -Another example of native-dependent code is support for features that
|
| -are really part of the target environment, but which require
|
| -@code{#include} files that are only available on the host system. Core
|
| -file handling and @code{setjmp} handling are two common cases.
|
| -
|
| -When you want to make @value{GDBN} work as the traditional native debugger
|
| -on a system, you will need to supply both target and native information.
|
| -
|
| -@section Source Tree Structure
|
| -@cindex @value{GDBN} source tree structure
|
| -
|
| -The @value{GDBN} source directory has a mostly flat structure---there
|
| -are only a few subdirectories. A file's name usually gives a hint as
|
| -to what it does; for example, @file{stabsread.c} reads stabs,
|
| -@file{dwarf2read.c} reads @sc{DWARF 2}, etc.
|
| -
|
| -Files that are related to some common task have names that share
|
| -common substrings. For example, @file{*-thread.c} files deal with
|
| -debugging threads on various platforms; @file{*read.c} files deal with
|
| -reading various kinds of symbol and object files; @file{inf*.c} files
|
| -deal with direct control of the @dfn{inferior program} (@value{GDBN}
|
| -parlance for the program being debugged).
|
| -
|
| -There are several dozens of files in the @file{*-tdep.c} family.
|
| -@samp{tdep} stands for @dfn{target-dependent code}---each of these
|
| -files implements debug support for a specific target architecture
|
| -(sparc, mips, etc). Usually, only one of these will be used in a
|
| -specific @value{GDBN} configuration (sometimes two, closely related).
|
| -
|
| -Similarly, there are many @file{*-nat.c} files, each one for native
|
| -debugging on a specific system (e.g., @file{sparc-linux-nat.c} is for
|
| -native debugging of Sparc machines running the Linux kernel).
|
| -
|
| -The few subdirectories of the source tree are:
|
| -
|
| -@table @file
|
| -@item cli
|
| -Code that implements @dfn{CLI}, the @value{GDBN} Command-Line
|
| -Interpreter. @xref{User Interface, Command Interpreter}.
|
| -
|
| -@item gdbserver
|
| -Code for the @value{GDBN} remote server.
|
| -
|
| -@item gdbtk
|
| -Code for Insight, the @value{GDBN} TK-based GUI front-end.
|
| -
|
| -@item mi
|
| -The @dfn{GDB/MI}, the @value{GDBN} Machine Interface interpreter.
|
| -
|
| -@item signals
|
| -Target signal translation code.
|
| -
|
| -@item tui
|
| -Code for @dfn{TUI}, the @value{GDBN} Text-mode full-screen User
|
| -Interface. @xref{User Interface, TUI}.
|
| -@end table
|
| -
|
| -@node Algorithms
|
| -
|
| -@chapter Algorithms
|
| -@cindex algorithms
|
| -
|
| -@value{GDBN} uses a number of debugging-specific algorithms. They are
|
| -often not very complicated, but get lost in the thicket of special
|
| -cases and real-world issues. This chapter describes the basic
|
| -algorithms and mentions some of the specific target definitions that
|
| -they use.
|
| -
|
| -@section Prologue Analysis
|
| -
|
| -@cindex prologue analysis
|
| -@cindex call frame information
|
| -@cindex CFI (call frame information)
|
| -To produce a backtrace and allow the user to manipulate older frames'
|
| -variables and arguments, @value{GDBN} needs to find the base addresses
|
| -of older frames, and discover where those frames' registers have been
|
| -saved. Since a frame's ``callee-saves'' registers get saved by
|
| -younger frames if and when they're reused, a frame's registers may be
|
| -scattered unpredictably across younger frames. This means that
|
| -changing the value of a register-allocated variable in an older frame
|
| -may actually entail writing to a save slot in some younger frame.
|
| -
|
| -Modern versions of GCC emit Dwarf call frame information (``CFI''),
|
| -which describes how to find frame base addresses and saved registers.
|
| -But CFI is not always available, so as a fallback @value{GDBN} uses a
|
| -technique called @dfn{prologue analysis} to find frame sizes and saved
|
| -registers. A prologue analyzer disassembles the function's machine
|
| -code starting from its entry point, and looks for instructions that
|
| -allocate frame space, save the stack pointer in a frame pointer
|
| -register, save registers, and so on. Obviously, this can't be done
|
| -accurately in general, but it's tractable to do well enough to be very
|
| -helpful. Prologue analysis predates the GNU toolchain's support for
|
| -CFI; at one time, prologue analysis was the only mechanism
|
| -@value{GDBN} used for stack unwinding at all, when the function
|
| -calling conventions didn't specify a fixed frame layout.
|
| -
|
| -In the olden days, function prologues were generated by hand-written,
|
| -target-specific code in GCC, and treated as opaque and untouchable by
|
| -optimizers. Looking at this code, it was usually straightforward to
|
| -write a prologue analyzer for @value{GDBN} that would accurately
|
| -understand all the prologues GCC would generate. However, over time
|
| -GCC became more aggressive about instruction scheduling, and began to
|
| -understand more about the semantics of the prologue instructions
|
| -themselves; in response, @value{GDBN}'s analyzers became more complex
|
| -and fragile. Keeping the prologue analyzers working as GCC (and the
|
| -instruction sets themselves) evolved became a substantial task.
|
| -
|
| -@cindex @file{prologue-value.c}
|
| -@cindex abstract interpretation of function prologues
|
| -@cindex pseudo-evaluation of function prologues
|
| -To try to address this problem, the code in @file{prologue-value.h}
|
| -and @file{prologue-value.c} provides a general framework for writing
|
| -prologue analyzers that are simpler and more robust than ad-hoc
|
| -analyzers. When we analyze a prologue using the prologue-value
|
| -framework, we're really doing ``abstract interpretation'' or
|
| -``pseudo-evaluation'': running the function's code in simulation, but
|
| -using conservative approximations of the values registers and memory
|
| -would hold when the code actually runs. For example, if our function
|
| -starts with the instruction:
|
| -
|
| -@example
|
| -addi r1, 42 # add 42 to r1
|
| -@end example
|
| -@noindent
|
| -we don't know exactly what value will be in @code{r1} after executing
|
| -this instruction, but we do know it'll be 42 greater than its original
|
| -value.
|
| -
|
| -If we then see an instruction like:
|
| -
|
| -@example
|
| -addi r1, 22 # add 22 to r1
|
| -@end example
|
| -@noindent
|
| -we still don't know what @code{r1's} value is, but again, we can say
|
| -it is now 64 greater than its original value.
|
| -
|
| -If the next instruction were:
|
| -
|
| -@example
|
| -mov r2, r1 # set r2 to r1's value
|
| -@end example
|
| -@noindent
|
| -then we can say that @code{r2's} value is now the original value of
|
| -@code{r1} plus 64.
|
| -
|
| -It's common for prologues to save registers on the stack, so we'll
|
| -need to track the values of stack frame slots, as well as the
|
| -registers. So after an instruction like this:
|
| -
|
| -@example
|
| -mov (fp+4), r2
|
| -@end example
|
| -@noindent
|
| -then we'd know that the stack slot four bytes above the frame pointer
|
| -holds the original value of @code{r1} plus 64.
|
| -
|
| -And so on.
|
| -
|
| -Of course, this can only go so far before it gets unreasonable. If we
|
| -wanted to be able to say anything about the value of @code{r1} after
|
| -the instruction:
|
| -
|
| -@example
|
| -xor r1, r3 # exclusive-or r1 and r3, place result in r1
|
| -@end example
|
| -@noindent
|
| -then things would get pretty complex. But remember, we're just doing
|
| -a conservative approximation; if exclusive-or instructions aren't
|
| -relevant to prologues, we can just say @code{r1}'s value is now
|
| -``unknown''. We can ignore things that are too complex, if that loss of
|
| -information is acceptable for our application.
|
| -
|
| -So when we say ``conservative approximation'' here, what we mean is an
|
| -approximation that is either accurate, or marked ``unknown'', but
|
| -never inaccurate.
|
| -
|
| -Using this framework, a prologue analyzer is simply an interpreter for
|
| -machine code, but one that uses conservative approximations for the
|
| -contents of registers and memory instead of actual values. Starting
|
| -from the function's entry point, you simulate instructions up to the
|
| -current PC, or an instruction that you don't know how to simulate.
|
| -Now you can examine the state of the registers and stack slots you've
|
| -kept track of.
|
| -
|
| -@itemize @bullet
|
| -
|
| -@item
|
| -To see how large your stack frame is, just check the value of the
|
| -stack pointer register; if it's the original value of the SP
|
| -minus a constant, then that constant is the stack frame's size.
|
| -If the SP's value has been marked as ``unknown'', then that means
|
| -the prologue has done something too complex for us to track, and
|
| -we don't know the frame size.
|
| -
|
| -@item
|
| -To see where we've saved the previous frame's registers, we just
|
| -search the values we've tracked --- stack slots, usually, but
|
| -registers, too, if you want --- for something equal to the register's
|
| -original value. If the calling conventions suggest a standard place
|
| -to save a given register, then we can check there first, but really,
|
| -anything that will get us back the original value will probably work.
|
| -@end itemize
|
| -
|
| -This does take some work. But prologue analyzers aren't
|
| -quick-and-simple pattern patching to recognize a few fixed prologue
|
| -forms any more; they're big, hairy functions. Along with inferior
|
| -function calls, prologue analysis accounts for a substantial portion
|
| -of the time needed to stabilize a @value{GDBN} port. So it's
|
| -worthwhile to look for an approach that will be easier to understand
|
| -and maintain. In the approach described above:
|
| -
|
| -@itemize @bullet
|
| -
|
| -@item
|
| -It's easier to see that the analyzer is correct: you just see
|
| -whether the analyzer properly (albeit conservatively) simulates
|
| -the effect of each instruction.
|
| -
|
| -@item
|
| -It's easier to extend the analyzer: you can add support for new
|
| -instructions, and know that you haven't broken anything that
|
| -wasn't already broken before.
|
| -
|
| -@item
|
| -It's orthogonal: to gather new information, you don't need to
|
| -complicate the code for each instruction. As long as your domain
|
| -of conservative values is already detailed enough to tell you
|
| -what you need, then all the existing instruction simulations are
|
| -already gathering the right data for you.
|
| -
|
| -@end itemize
|
| -
|
| -The file @file{prologue-value.h} contains detailed comments explaining
|
| -the framework and how to use it.
|
| -
|
| -
|
| -@section Breakpoint Handling
|
| -
|
| -@cindex breakpoints
|
| -In general, a breakpoint is a user-designated location in the program
|
| -where the user wants to regain control if program execution ever reaches
|
| -that location.
|
| -
|
| -There are two main ways to implement breakpoints; either as ``hardware''
|
| -breakpoints or as ``software'' breakpoints.
|
| -
|
| -@cindex hardware breakpoints
|
| -@cindex program counter
|
| -Hardware breakpoints are sometimes available as a builtin debugging
|
| -features with some chips. Typically these work by having dedicated
|
| -register into which the breakpoint address may be stored. If the PC
|
| -(shorthand for @dfn{program counter})
|
| -ever matches a value in a breakpoint registers, the CPU raises an
|
| -exception and reports it to @value{GDBN}.
|
| -
|
| -Another possibility is when an emulator is in use; many emulators
|
| -include circuitry that watches the address lines coming out from the
|
| -processor, and force it to stop if the address matches a breakpoint's
|
| -address.
|
| -
|
| -A third possibility is that the target already has the ability to do
|
| -breakpoints somehow; for instance, a ROM monitor may do its own
|
| -software breakpoints. So although these are not literally ``hardware
|
| -breakpoints'', from @value{GDBN}'s point of view they work the same;
|
| -@value{GDBN} need not do anything more than set the breakpoint and wait
|
| -for something to happen.
|
| -
|
| -Since they depend on hardware resources, hardware breakpoints may be
|
| -limited in number; when the user asks for more, @value{GDBN} will
|
| -start trying to set software breakpoints. (On some architectures,
|
| -notably the 32-bit x86 platforms, @value{GDBN} cannot always know
|
| -whether there's enough hardware resources to insert all the hardware
|
| -breakpoints and watchpoints. On those platforms, @value{GDBN} prints
|
| -an error message only when the program being debugged is continued.)
|
| -
|
| -@cindex software breakpoints
|
| -Software breakpoints require @value{GDBN} to do somewhat more work.
|
| -The basic theory is that @value{GDBN} will replace a program
|
| -instruction with a trap, illegal divide, or some other instruction
|
| -that will cause an exception, and then when it's encountered,
|
| -@value{GDBN} will take the exception and stop the program. When the
|
| -user says to continue, @value{GDBN} will restore the original
|
| -instruction, single-step, re-insert the trap, and continue on.
|
| -
|
| -Since it literally overwrites the program being tested, the program area
|
| -must be writable, so this technique won't work on programs in ROM. It
|
| -can also distort the behavior of programs that examine themselves,
|
| -although such a situation would be highly unusual.
|
| -
|
| -Also, the software breakpoint instruction should be the smallest size of
|
| -instruction, so it doesn't overwrite an instruction that might be a jump
|
| -target, and cause disaster when the program jumps into the middle of the
|
| -breakpoint instruction. (Strictly speaking, the breakpoint must be no
|
| -larger than the smallest interval between instructions that may be jump
|
| -targets; perhaps there is an architecture where only even-numbered
|
| -instructions may jumped to.) Note that it's possible for an instruction
|
| -set not to have any instructions usable for a software breakpoint,
|
| -although in practice only the ARC has failed to define such an
|
| -instruction.
|
| -
|
| -Basic breakpoint object handling is in @file{breakpoint.c}. However,
|
| -much of the interesting breakpoint action is in @file{infrun.c}.
|
| -
|
| -@table @code
|
| -@cindex insert or remove software breakpoint
|
| -@findex target_remove_breakpoint
|
| -@findex target_insert_breakpoint
|
| -@item target_remove_breakpoint (@var{bp_tgt})
|
| -@itemx target_insert_breakpoint (@var{bp_tgt})
|
| -Insert or remove a software breakpoint at address
|
| -@code{@var{bp_tgt}->placed_address}. Returns zero for success,
|
| -non-zero for failure. On input, @var{bp_tgt} contains the address of the
|
| -breakpoint, and is otherwise initialized to zero. The fields of the
|
| -@code{struct bp_target_info} pointed to by @var{bp_tgt} are updated
|
| -to contain other information about the breakpoint on output. The field
|
| -@code{placed_address} may be updated if the breakpoint was placed at a
|
| -related address; the field @code{shadow_contents} contains the real
|
| -contents of the bytes where the breakpoint has been inserted,
|
| -if reading memory would return the breakpoint instead of the
|
| -underlying memory; the field @code{shadow_len} is the length of
|
| -memory cached in @code{shadow_contents}, if any; and the field
|
| -@code{placed_size} is optionally set and used by the target, if
|
| -it could differ from @code{shadow_len}.
|
| -
|
| -For example, the remote target @samp{Z0} packet does not require
|
| -shadowing memory, so @code{shadow_len} is left at zero. However,
|
| -the length reported by @code{gdbarch_breakpoint_from_pc} is cached in
|
| -@code{placed_size}, so that a matching @samp{z0} packet can be
|
| -used to remove the breakpoint.
|
| -
|
| -@cindex insert or remove hardware breakpoint
|
| -@findex target_remove_hw_breakpoint
|
| -@findex target_insert_hw_breakpoint
|
| -@item target_remove_hw_breakpoint (@var{bp_tgt})
|
| -@itemx target_insert_hw_breakpoint (@var{bp_tgt})
|
| -Insert or remove a hardware-assisted breakpoint at address
|
| -@code{@var{bp_tgt}->placed_address}. Returns zero for success,
|
| -non-zero for failure. See @code{target_insert_breakpoint} for
|
| -a description of the @code{struct bp_target_info} pointed to by
|
| -@var{bp_tgt}; the @code{shadow_contents} and
|
| -@code{shadow_len} members are not used for hardware breakpoints,
|
| -but @code{placed_size} may be.
|
| -@end table
|
| -
|
| -@section Single Stepping
|
| -
|
| -@section Signal Handling
|
| -
|
| -@section Thread Handling
|
| -
|
| -@section Inferior Function Calls
|
| -
|
| -@section Longjmp Support
|
| -
|
| -@cindex @code{longjmp} debugging
|
| -@value{GDBN} has support for figuring out that the target is doing a
|
| -@code{longjmp} and for stopping at the target of the jump, if we are
|
| -stepping. This is done with a few specialized internal breakpoints,
|
| -which are visible in the output of the @samp{maint info breakpoint}
|
| -command.
|
| -
|
| -@findex gdbarch_get_longjmp_target
|
| -To make this work, you need to define a function called
|
| -@code{gdbarch_get_longjmp_target}, which will examine the
|
| -@code{jmp_buf} structure and extract the @code{longjmp} target address.
|
| -Since @code{jmp_buf} is target specific and typically defined in a
|
| -target header not available to @value{GDBN}, you will need to
|
| -determine the offset of the PC manually and return that; many targets
|
| -define a @code{jb_pc_offset} field in the tdep structure to save the
|
| -value once calculated.
|
| -
|
| -@section Watchpoints
|
| -@cindex watchpoints
|
| -
|
| -Watchpoints are a special kind of breakpoints (@pxref{Algorithms,
|
| -breakpoints}) which break when data is accessed rather than when some
|
| -instruction is executed. When you have data which changes without
|
| -your knowing what code does that, watchpoints are the silver bullet to
|
| -hunt down and kill such bugs.
|
| -
|
| -@cindex hardware watchpoints
|
| -@cindex software watchpoints
|
| -Watchpoints can be either hardware-assisted or not; the latter type is
|
| -known as ``software watchpoints.'' @value{GDBN} always uses
|
| -hardware-assisted watchpoints if they are available, and falls back on
|
| -software watchpoints otherwise. Typical situations where @value{GDBN}
|
| -will use software watchpoints are:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -The watched memory region is too large for the underlying hardware
|
| -watchpoint support. For example, each x86 debug register can watch up
|
| -to 4 bytes of memory, so trying to watch data structures whose size is
|
| -more than 16 bytes will cause @value{GDBN} to use software
|
| -watchpoints.
|
| -
|
| -@item
|
| -The value of the expression to be watched depends on data held in
|
| -registers (as opposed to memory).
|
| -
|
| -@item
|
| -Too many different watchpoints requested. (On some architectures,
|
| -this situation is impossible to detect until the debugged program is
|
| -resumed.) Note that x86 debug registers are used both for hardware
|
| -breakpoints and for watchpoints, so setting too many hardware
|
| -breakpoints might cause watchpoint insertion to fail.
|
| -
|
| -@item
|
| -No hardware-assisted watchpoints provided by the target
|
| -implementation.
|
| -@end itemize
|
| -
|
| -Software watchpoints are very slow, since @value{GDBN} needs to
|
| -single-step the program being debugged and test the value of the
|
| -watched expression(s) after each instruction. The rest of this
|
| -section is mostly irrelevant for software watchpoints.
|
| -
|
| -When the inferior stops, @value{GDBN} tries to establish, among other
|
| -possible reasons, whether it stopped due to a watchpoint being hit.
|
| -It first uses @code{STOPPED_BY_WATCHPOINT} to see if any watchpoint
|
| -was hit. If not, all watchpoint checking is skipped.
|
| -
|
| -Then @value{GDBN} calls @code{target_stopped_data_address} exactly
|
| -once. This method returns the address of the watchpoint which
|
| -triggered, if the target can determine it. If the triggered address
|
| -is available, @value{GDBN} compares the address returned by this
|
| -method with each watched memory address in each active watchpoint.
|
| -For data-read and data-access watchpoints, @value{GDBN} announces
|
| -every watchpoint that watches the triggered address as being hit.
|
| -For this reason, data-read and data-access watchpoints
|
| -@emph{require} that the triggered address be available; if not, read
|
| -and access watchpoints will never be considered hit. For data-write
|
| -watchpoints, if the triggered address is available, @value{GDBN}
|
| -considers only those watchpoints which match that address;
|
| -otherwise, @value{GDBN} considers all data-write watchpoints. For
|
| -each data-write watchpoint that @value{GDBN} considers, it evaluates
|
| -the expression whose value is being watched, and tests whether the
|
| -watched value has changed. Watchpoints whose watched values have
|
| -changed are announced as hit.
|
| -
|
| -@c FIXME move these to the main lists of target/native defns
|
| -
|
| -@value{GDBN} uses several macros and primitives to support hardware
|
| -watchpoints:
|
| -
|
| -@table @code
|
| -@findex TARGET_CAN_USE_HARDWARE_WATCHPOINT
|
| -@item TARGET_CAN_USE_HARDWARE_WATCHPOINT (@var{type}, @var{count}, @var{other})
|
| -Return the number of hardware watchpoints of type @var{type} that are
|
| -possible to be set. The value is positive if @var{count} watchpoints
|
| -of this type can be set, zero if setting watchpoints of this type is
|
| -not supported, and negative if @var{count} is more than the maximum
|
| -number of watchpoints of type @var{type} that can be set. @var{other}
|
| -is non-zero if other types of watchpoints are currently enabled (there
|
| -are architectures which cannot set watchpoints of different types at
|
| -the same time).
|
| -
|
| -@findex TARGET_REGION_OK_FOR_HW_WATCHPOINT
|
| -@item TARGET_REGION_OK_FOR_HW_WATCHPOINT (@var{addr}, @var{len})
|
| -Return non-zero if hardware watchpoints can be used to watch a region
|
| -whose address is @var{addr} and whose length in bytes is @var{len}.
|
| -
|
| -@cindex insert or remove hardware watchpoint
|
| -@findex target_insert_watchpoint
|
| -@findex target_remove_watchpoint
|
| -@item target_insert_watchpoint (@var{addr}, @var{len}, @var{type})
|
| -@itemx target_remove_watchpoint (@var{addr}, @var{len}, @var{type})
|
| -Insert or remove a hardware watchpoint starting at @var{addr}, for
|
| -@var{len} bytes. @var{type} is the watchpoint type, one of the
|
| -possible values of the enumerated data type @code{target_hw_bp_type},
|
| -defined by @file{breakpoint.h} as follows:
|
| -
|
| -@smallexample
|
| - enum target_hw_bp_type
|
| - @{
|
| - hw_write = 0, /* Common (write) HW watchpoint */
|
| - hw_read = 1, /* Read HW watchpoint */
|
| - hw_access = 2, /* Access (read or write) HW watchpoint */
|
| - hw_execute = 3 /* Execute HW breakpoint */
|
| - @};
|
| -@end smallexample
|
| -
|
| -@noindent
|
| -These two macros should return 0 for success, non-zero for failure.
|
| -
|
| -@findex target_stopped_data_address
|
| -@item target_stopped_data_address (@var{addr_p})
|
| -If the inferior has some watchpoint that triggered, place the address
|
| -associated with the watchpoint at the location pointed to by
|
| -@var{addr_p} and return non-zero. Otherwise, return zero. This
|
| -is required for data-read and data-access watchpoints. It is
|
| -not required for data-write watchpoints, but @value{GDBN} uses
|
| -it to improve handling of those also.
|
| -
|
| -@value{GDBN} will only call this method once per watchpoint stop,
|
| -immediately after calling @code{STOPPED_BY_WATCHPOINT}. If the
|
| -target's watchpoint indication is sticky, i.e., stays set after
|
| -resuming, this method should clear it. For instance, the x86 debug
|
| -control register has sticky triggered flags.
|
| -
|
| -@findex target_watchpoint_addr_within_range
|
| -@item target_watchpoint_addr_within_range (@var{target}, @var{addr}, @var{start}, @var{length})
|
| -Check whether @var{addr} (as returned by @code{target_stopped_data_address})
|
| -lies within the hardware-defined watchpoint region described by
|
| -@var{start} and @var{length}. This only needs to be provided if the
|
| -granularity of a watchpoint is greater than one byte, i.e., if the
|
| -watchpoint can also trigger on nearby addresses outside of the watched
|
| -region.
|
| -
|
| -@findex HAVE_STEPPABLE_WATCHPOINT
|
| -@item HAVE_STEPPABLE_WATCHPOINT
|
| -If defined to a non-zero value, it is not necessary to disable a
|
| -watchpoint to step over it. Like @code{gdbarch_have_nonsteppable_watchpoint},
|
| -this is usually set when watchpoints trigger at the instruction
|
| -which will perform an interesting read or write. It should be
|
| -set if there is a temporary disable bit which allows the processor
|
| -to step over the interesting instruction without raising the
|
| -watchpoint exception again.
|
| -
|
| -@findex gdbarch_have_nonsteppable_watchpoint
|
| -@item int gdbarch_have_nonsteppable_watchpoint (@var{gdbarch})
|
| -If it returns a non-zero value, @value{GDBN} should disable a
|
| -watchpoint to step the inferior over it. This is usually set when
|
| -watchpoints trigger at the instruction which will perform an
|
| -interesting read or write.
|
| -
|
| -@findex HAVE_CONTINUABLE_WATCHPOINT
|
| -@item HAVE_CONTINUABLE_WATCHPOINT
|
| -If defined to a non-zero value, it is possible to continue the
|
| -inferior after a watchpoint has been hit. This is usually set
|
| -when watchpoints trigger at the instruction following an interesting
|
| -read or write.
|
| -
|
| -@findex STOPPED_BY_WATCHPOINT
|
| -@item STOPPED_BY_WATCHPOINT (@var{wait_status})
|
| -Return non-zero if stopped by a watchpoint. @var{wait_status} is of
|
| -the type @code{struct target_waitstatus}, defined by @file{target.h}.
|
| -Normally, this macro is defined to invoke the function pointed to by
|
| -the @code{to_stopped_by_watchpoint} member of the structure (of the
|
| -type @code{target_ops}, defined on @file{target.h}) that describes the
|
| -target-specific operations; @code{to_stopped_by_watchpoint} ignores
|
| -the @var{wait_status} argument.
|
| -
|
| -@value{GDBN} does not require the non-zero value returned by
|
| -@code{STOPPED_BY_WATCHPOINT} to be 100% correct, so if a target cannot
|
| -determine for sure whether the inferior stopped due to a watchpoint,
|
| -it could return non-zero ``just in case''.
|
| -@end table
|
| -
|
| -@subsection Watchpoints and Threads
|
| -@cindex watchpoints, with threads
|
| -
|
| -@value{GDBN} only supports process-wide watchpoints, which trigger
|
| -in all threads. @value{GDBN} uses the thread ID to make watchpoints
|
| -act as if they were thread-specific, but it cannot set hardware
|
| -watchpoints that only trigger in a specific thread. Therefore, even
|
| -if the target supports threads, per-thread debug registers, and
|
| -watchpoints which only affect a single thread, it should set the
|
| -per-thread debug registers for all threads to the same value. On
|
| -@sc{gnu}/Linux native targets, this is accomplished by using
|
| -@code{ALL_LWPS} in @code{target_insert_watchpoint} and
|
| -@code{target_remove_watchpoint} and by using
|
| -@code{linux_set_new_thread} to register a handler for newly created
|
| -threads.
|
| -
|
| -@value{GDBN}'s @sc{gnu}/Linux support only reports a single event
|
| -at a time, although multiple events can trigger simultaneously for
|
| -multi-threaded programs. When multiple events occur, @file{linux-nat.c}
|
| -queues subsequent events and returns them the next time the program
|
| -is resumed. This means that @code{STOPPED_BY_WATCHPOINT} and
|
| -@code{target_stopped_data_address} only need to consult the current
|
| -thread's state---the thread indicated by @code{inferior_ptid}. If
|
| -two threads have hit watchpoints simultaneously, those routines
|
| -will be called a second time for the second thread.
|
| -
|
| -@subsection x86 Watchpoints
|
| -@cindex x86 debug registers
|
| -@cindex watchpoints, on x86
|
| -
|
| -The 32-bit Intel x86 (a.k.a.@: ia32) processors feature special debug
|
| -registers designed to facilitate debugging. @value{GDBN} provides a
|
| -generic library of functions that x86-based ports can use to implement
|
| -support for watchpoints and hardware-assisted breakpoints. This
|
| -subsection documents the x86 watchpoint facilities in @value{GDBN}.
|
| -
|
| -(At present, the library functions read and write debug registers directly, and are
|
| -thus only available for native configurations.)
|
| -
|
| -To use the generic x86 watchpoint support, a port should do the
|
| -following:
|
| -
|
| -@itemize @bullet
|
| -@findex I386_USE_GENERIC_WATCHPOINTS
|
| -@item
|
| -Define the macro @code{I386_USE_GENERIC_WATCHPOINTS} somewhere in the
|
| -target-dependent headers.
|
| -
|
| -@item
|
| -Include the @file{config/i386/nm-i386.h} header file @emph{after}
|
| -defining @code{I386_USE_GENERIC_WATCHPOINTS}.
|
| -
|
| -@item
|
| -Add @file{i386-nat.o} to the value of the Make variable
|
| -@code{NATDEPFILES} (@pxref{Native Debugging, NATDEPFILES}).
|
| -
|
| -@item
|
| -Provide implementations for the @code{I386_DR_LOW_*} macros described
|
| -below. Typically, each macro should call a target-specific function
|
| -which does the real work.
|
| -@end itemize
|
| -
|
| -The x86 watchpoint support works by maintaining mirror images of the
|
| -debug registers. Values are copied between the mirror images and the
|
| -real debug registers via a set of macros which each target needs to
|
| -provide:
|
| -
|
| -@table @code
|
| -@findex I386_DR_LOW_SET_CONTROL
|
| -@item I386_DR_LOW_SET_CONTROL (@var{val})
|
| -Set the Debug Control (DR7) register to the value @var{val}.
|
| -
|
| -@findex I386_DR_LOW_SET_ADDR
|
| -@item I386_DR_LOW_SET_ADDR (@var{idx}, @var{addr})
|
| -Put the address @var{addr} into the debug register number @var{idx}.
|
| -
|
| -@findex I386_DR_LOW_RESET_ADDR
|
| -@item I386_DR_LOW_RESET_ADDR (@var{idx})
|
| -Reset (i.e.@: zero out) the address stored in the debug register
|
| -number @var{idx}.
|
| -
|
| -@findex I386_DR_LOW_GET_STATUS
|
| -@item I386_DR_LOW_GET_STATUS
|
| -Return the value of the Debug Status (DR6) register. This value is
|
| -used immediately after it is returned by
|
| -@code{I386_DR_LOW_GET_STATUS}, so as to support per-thread status
|
| -register values.
|
| -@end table
|
| -
|
| -For each one of the 4 debug registers (whose indices are from 0 to 3)
|
| -that store addresses, a reference count is maintained by @value{GDBN},
|
| -to allow sharing of debug registers by several watchpoints. This
|
| -allows users to define several watchpoints that watch the same
|
| -expression, but with different conditions and/or commands, without
|
| -wasting debug registers which are in short supply. @value{GDBN}
|
| -maintains the reference counts internally, targets don't have to do
|
| -anything to use this feature.
|
| -
|
| -The x86 debug registers can each watch a region that is 1, 2, or 4
|
| -bytes long. The ia32 architecture requires that each watched region
|
| -be appropriately aligned: 2-byte region on 2-byte boundary, 4-byte
|
| -region on 4-byte boundary. However, the x86 watchpoint support in
|
| -@value{GDBN} can watch unaligned regions and regions larger than 4
|
| -bytes (up to 16 bytes) by allocating several debug registers to watch
|
| -a single region. This allocation of several registers per a watched
|
| -region is also done automatically without target code intervention.
|
| -
|
| -The generic x86 watchpoint support provides the following API for the
|
| -@value{GDBN}'s application code:
|
| -
|
| -@table @code
|
| -@findex i386_region_ok_for_watchpoint
|
| -@item i386_region_ok_for_watchpoint (@var{addr}, @var{len})
|
| -The macro @code{TARGET_REGION_OK_FOR_HW_WATCHPOINT} is set to call
|
| -this function. It counts the number of debug registers required to
|
| -watch a given region, and returns a non-zero value if that number is
|
| -less than 4, the number of debug registers available to x86
|
| -processors.
|
| -
|
| -@findex i386_stopped_data_address
|
| -@item i386_stopped_data_address (@var{addr_p})
|
| -The target function
|
| -@code{target_stopped_data_address} is set to call this function.
|
| -This
|
| -function examines the breakpoint condition bits in the DR6 Debug
|
| -Status register, as returned by the @code{I386_DR_LOW_GET_STATUS}
|
| -macro, and returns the address associated with the first bit that is
|
| -set in DR6.
|
| -
|
| -@findex i386_stopped_by_watchpoint
|
| -@item i386_stopped_by_watchpoint (void)
|
| -The macro @code{STOPPED_BY_WATCHPOINT}
|
| -is set to call this function. The
|
| -argument passed to @code{STOPPED_BY_WATCHPOINT} is ignored. This
|
| -function examines the breakpoint condition bits in the DR6 Debug
|
| -Status register, as returned by the @code{I386_DR_LOW_GET_STATUS}
|
| -macro, and returns true if any bit is set. Otherwise, false is
|
| -returned.
|
| -
|
| -@findex i386_insert_watchpoint
|
| -@findex i386_remove_watchpoint
|
| -@item i386_insert_watchpoint (@var{addr}, @var{len}, @var{type})
|
| -@itemx i386_remove_watchpoint (@var{addr}, @var{len}, @var{type})
|
| -Insert or remove a watchpoint. The macros
|
| -@code{target_insert_watchpoint} and @code{target_remove_watchpoint}
|
| -are set to call these functions. @code{i386_insert_watchpoint} first
|
| -looks for a debug register which is already set to watch the same
|
| -region for the same access types; if found, it just increments the
|
| -reference count of that debug register, thus implementing debug
|
| -register sharing between watchpoints. If no such register is found,
|
| -the function looks for a vacant debug register, sets its mirrored
|
| -value to @var{addr}, sets the mirrored value of DR7 Debug Control
|
| -register as appropriate for the @var{len} and @var{type} parameters,
|
| -and then passes the new values of the debug register and DR7 to the
|
| -inferior by calling @code{I386_DR_LOW_SET_ADDR} and
|
| -@code{I386_DR_LOW_SET_CONTROL}. If more than one debug register is
|
| -required to cover the given region, the above process is repeated for
|
| -each debug register.
|
| -
|
| -@code{i386_remove_watchpoint} does the opposite: it resets the address
|
| -in the mirrored value of the debug register and its read/write and
|
| -length bits in the mirrored value of DR7, then passes these new
|
| -values to the inferior via @code{I386_DR_LOW_RESET_ADDR} and
|
| -@code{I386_DR_LOW_SET_CONTROL}. If a register is shared by several
|
| -watchpoints, each time a @code{i386_remove_watchpoint} is called, it
|
| -decrements the reference count, and only calls
|
| -@code{I386_DR_LOW_RESET_ADDR} and @code{I386_DR_LOW_SET_CONTROL} when
|
| -the count goes to zero.
|
| -
|
| -@findex i386_insert_hw_breakpoint
|
| -@findex i386_remove_hw_breakpoint
|
| -@item i386_insert_hw_breakpoint (@var{bp_tgt})
|
| -@itemx i386_remove_hw_breakpoint (@var{bp_tgt})
|
| -These functions insert and remove hardware-assisted breakpoints. The
|
| -macros @code{target_insert_hw_breakpoint} and
|
| -@code{target_remove_hw_breakpoint} are set to call these functions.
|
| -The argument is a @code{struct bp_target_info *}, as described in
|
| -the documentation for @code{target_insert_breakpoint}.
|
| -These functions work like @code{i386_insert_watchpoint} and
|
| -@code{i386_remove_watchpoint}, respectively, except that they set up
|
| -the debug registers to watch instruction execution, and each
|
| -hardware-assisted breakpoint always requires exactly one debug
|
| -register.
|
| -
|
| -@findex i386_cleanup_dregs
|
| -@item i386_cleanup_dregs (void)
|
| -This function clears all the reference counts, addresses, and control
|
| -bits in the mirror images of the debug registers. It doesn't affect
|
| -the actual debug registers in the inferior process.
|
| -@end table
|
| -
|
| -@noindent
|
| -@strong{Notes:}
|
| -@enumerate 1
|
| -@item
|
| -x86 processors support setting watchpoints on I/O reads or writes.
|
| -However, since no target supports this (as of March 2001), and since
|
| -@code{enum target_hw_bp_type} doesn't even have an enumeration for I/O
|
| -watchpoints, this feature is not yet available to @value{GDBN} running
|
| -on x86.
|
| -
|
| -@item
|
| -x86 processors can enable watchpoints locally, for the current task
|
| -only, or globally, for all the tasks. For each debug register,
|
| -there's a bit in the DR7 Debug Control register that determines
|
| -whether the associated address is watched locally or globally. The
|
| -current implementation of x86 watchpoint support in @value{GDBN}
|
| -always sets watchpoints to be locally enabled, since global
|
| -watchpoints might interfere with the underlying OS and are probably
|
| -unavailable in many platforms.
|
| -@end enumerate
|
| -
|
| -@section Checkpoints
|
| -@cindex checkpoints
|
| -@cindex restart
|
| -In the abstract, a checkpoint is a point in the execution history of
|
| -the program, which the user may wish to return to at some later time.
|
| -
|
| -Internally, a checkpoint is a saved copy of the program state, including
|
| -whatever information is required in order to restore the program to that
|
| -state at a later time. This can be expected to include the state of
|
| -registers and memory, and may include external state such as the state
|
| -of open files and devices.
|
| -
|
| -There are a number of ways in which checkpoints may be implemented
|
| -in gdb, e.g.@: as corefiles, as forked processes, and as some opaque
|
| -method implemented on the target side.
|
| -
|
| -A corefile can be used to save an image of target memory and register
|
| -state, which can in principle be restored later --- but corefiles do
|
| -not typically include information about external entities such as
|
| -open files. Currently this method is not implemented in gdb.
|
| -
|
| -A forked process can save the state of user memory and registers,
|
| -as well as some subset of external (kernel) state. This method
|
| -is used to implement checkpoints on Linux, and in principle might
|
| -be used on other systems.
|
| -
|
| -Some targets, e.g.@: simulators, might have their own built-in
|
| -method for saving checkpoints, and gdb might be able to take
|
| -advantage of that capability without necessarily knowing any
|
| -details of how it is done.
|
| -
|
| -
|
| -@section Observing changes in @value{GDBN} internals
|
| -@cindex observer pattern interface
|
| -@cindex notifications about changes in internals
|
| -
|
| -In order to function properly, several modules need to be notified when
|
| -some changes occur in the @value{GDBN} internals. Traditionally, these
|
| -modules have relied on several paradigms, the most common ones being
|
| -hooks and gdb-events. Unfortunately, none of these paradigms was
|
| -versatile enough to become the standard notification mechanism in
|
| -@value{GDBN}. The fact that they only supported one ``client'' was also
|
| -a strong limitation.
|
| -
|
| -A new paradigm, based on the Observer pattern of the @cite{Design
|
| -Patterns} book, has therefore been implemented. The goal was to provide
|
| -a new interface overcoming the issues with the notification mechanisms
|
| -previously available. This new interface needed to be strongly typed,
|
| -easy to extend, and versatile enough to be used as the standard
|
| -interface when adding new notifications.
|
| -
|
| -See @ref{GDB Observers} for a brief description of the observers
|
| -currently implemented in GDB. The rationale for the current
|
| -implementation is also briefly discussed.
|
| -
|
| -@node User Interface
|
| -
|
| -@chapter User Interface
|
| -
|
| -@value{GDBN} has several user interfaces, of which the traditional
|
| -command-line interface is perhaps the most familiar.
|
| -
|
| -@section Command Interpreter
|
| -
|
| -@cindex command interpreter
|
| -@cindex CLI
|
| -The command interpreter in @value{GDBN} is fairly simple. It is designed to
|
| -allow for the set of commands to be augmented dynamically, and also
|
| -has a recursive subcommand capability, where the first argument to
|
| -a command may itself direct a lookup on a different command list.
|
| -
|
| -For instance, the @samp{set} command just starts a lookup on the
|
| -@code{setlist} command list, while @samp{set thread} recurses
|
| -to the @code{set_thread_cmd_list}.
|
| -
|
| -@findex add_cmd
|
| -@findex add_com
|
| -To add commands in general, use @code{add_cmd}. @code{add_com} adds to
|
| -the main command list, and should be used for those commands. The usual
|
| -place to add commands is in the @code{_initialize_@var{xyz}} routines at
|
| -the ends of most source files.
|
| -
|
| -@findex add_setshow_cmd
|
| -@findex add_setshow_cmd_full
|
| -To add paired @samp{set} and @samp{show} commands, use
|
| -@code{add_setshow_cmd} or @code{add_setshow_cmd_full}. The former is
|
| -a slightly simpler interface which is useful when you don't need to
|
| -further modify the new command structures, while the latter returns
|
| -the new command structures for manipulation.
|
| -
|
| -@cindex deprecating commands
|
| -@findex deprecate_cmd
|
| -Before removing commands from the command set it is a good idea to
|
| -deprecate them for some time. Use @code{deprecate_cmd} on commands or
|
| -aliases to set the deprecated flag. @code{deprecate_cmd} takes a
|
| -@code{struct cmd_list_element} as it's first argument. You can use the
|
| -return value from @code{add_com} or @code{add_cmd} to deprecate the
|
| -command immediately after it is created.
|
| -
|
| -The first time a command is used the user will be warned and offered a
|
| -replacement (if one exists). Note that the replacement string passed to
|
| -@code{deprecate_cmd} should be the full name of the command, i.e., the
|
| -entire string the user should type at the command line.
|
| -
|
| -@anchor{UI-Independent Output}
|
| -@section UI-Independent Output---the @code{ui_out} Functions
|
| -@c This section is based on the documentation written by Fernando
|
| -@c Nasser <fnasser@redhat.com>.
|
| -
|
| -@cindex @code{ui_out} functions
|
| -The @code{ui_out} functions present an abstraction level for the
|
| -@value{GDBN} output code. They hide the specifics of different user
|
| -interfaces supported by @value{GDBN}, and thus free the programmer
|
| -from the need to write several versions of the same code, one each for
|
| -every UI, to produce output.
|
| -
|
| -@subsection Overview and Terminology
|
| -
|
| -In general, execution of each @value{GDBN} command produces some sort
|
| -of output, and can even generate an input request.
|
| -
|
| -Output can be generated for the following purposes:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -to display a @emph{result} of an operation;
|
| -
|
| -@item
|
| -to convey @emph{info} or produce side-effects of a requested
|
| -operation;
|
| -
|
| -@item
|
| -to provide a @emph{notification} of an asynchronous event (including
|
| -progress indication of a prolonged asynchronous operation);
|
| -
|
| -@item
|
| -to display @emph{error messages} (including warnings);
|
| -
|
| -@item
|
| -to show @emph{debug data};
|
| -
|
| -@item
|
| -to @emph{query} or prompt a user for input (a special case).
|
| -@end itemize
|
| -
|
| -@noindent
|
| -This section mainly concentrates on how to build result output,
|
| -although some of it also applies to other kinds of output.
|
| -
|
| -Generation of output that displays the results of an operation
|
| -involves one or more of the following:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -output of the actual data
|
| -
|
| -@item
|
| -formatting the output as appropriate for console output, to make it
|
| -easily readable by humans
|
| -
|
| -@item
|
| -machine oriented formatting--a more terse formatting to allow for easy
|
| -parsing by programs which read @value{GDBN}'s output
|
| -
|
| -@item
|
| -annotation, whose purpose is to help legacy GUIs to identify interesting
|
| -parts in the output
|
| -@end itemize
|
| -
|
| -The @code{ui_out} routines take care of the first three aspects.
|
| -Annotations are provided by separate annotation routines. Note that use
|
| -of annotations for an interface between a GUI and @value{GDBN} is
|
| -deprecated.
|
| -
|
| -Output can be in the form of a single item, which we call a @dfn{field};
|
| -a @dfn{list} consisting of identical fields; a @dfn{tuple} consisting of
|
| -non-identical fields; or a @dfn{table}, which is a tuple consisting of a
|
| -header and a body. In a BNF-like form:
|
| -
|
| -@table @code
|
| -@item <table> @expansion{}
|
| -@code{<header> <body>}
|
| -@item <header> @expansion{}
|
| -@code{@{ <column> @}}
|
| -@item <column> @expansion{}
|
| -@code{<width> <alignment> <title>}
|
| -@item <body> @expansion{}
|
| -@code{@{<row>@}}
|
| -@end table
|
| -
|
| -
|
| -@subsection General Conventions
|
| -
|
| -Most @code{ui_out} routines are of type @code{void}, the exceptions are
|
| -@code{ui_out_stream_new} (which returns a pointer to the newly created
|
| -object) and the @code{make_cleanup} routines.
|
| -
|
| -The first parameter is always the @code{ui_out} vector object, a pointer
|
| -to a @code{struct ui_out}.
|
| -
|
| -The @var{format} parameter is like in @code{printf} family of functions.
|
| -When it is present, there must also be a variable list of arguments
|
| -sufficient used to satisfy the @code{%} specifiers in the supplied
|
| -format.
|
| -
|
| -When a character string argument is not used in a @code{ui_out} function
|
| -call, a @code{NULL} pointer has to be supplied instead.
|
| -
|
| -
|
| -@subsection Table, Tuple and List Functions
|
| -
|
| -@cindex list output functions
|
| -@cindex table output functions
|
| -@cindex tuple output functions
|
| -This section introduces @code{ui_out} routines for building lists,
|
| -tuples and tables. The routines to output the actual data items
|
| -(fields) are presented in the next section.
|
| -
|
| -To recap: A @dfn{tuple} is a sequence of @dfn{fields}, each field
|
| -containing information about an object; a @dfn{list} is a sequence of
|
| -fields where each field describes an identical object.
|
| -
|
| -Use the @dfn{table} functions when your output consists of a list of
|
| -rows (tuples) and the console output should include a heading. Use this
|
| -even when you are listing just one object but you still want the header.
|
| -
|
| -@cindex nesting level in @code{ui_out} functions
|
| -Tables can not be nested. Tuples and lists can be nested up to a
|
| -maximum of five levels.
|
| -
|
| -The overall structure of the table output code is something like this:
|
| -
|
| -@smallexample
|
| - ui_out_table_begin
|
| - ui_out_table_header
|
| - @dots{}
|
| - ui_out_table_body
|
| - ui_out_tuple_begin
|
| - ui_out_field_*
|
| - @dots{}
|
| - ui_out_tuple_end
|
| - @dots{}
|
| - ui_out_table_end
|
| -@end smallexample
|
| -
|
| -Here is the description of table-, tuple- and list-related @code{ui_out}
|
| -functions:
|
| -
|
| -@deftypefun void ui_out_table_begin (struct ui_out *@var{uiout}, int @var{nbrofcols}, int @var{nr_rows}, const char *@var{tblid})
|
| -The function @code{ui_out_table_begin} marks the beginning of the output
|
| -of a table. It should always be called before any other @code{ui_out}
|
| -function for a given table. @var{nbrofcols} is the number of columns in
|
| -the table. @var{nr_rows} is the number of rows in the table.
|
| -@var{tblid} is an optional string identifying the table. The string
|
| -pointed to by @var{tblid} is copied by the implementation of
|
| -@code{ui_out_table_begin}, so the application can free the string if it
|
| -was @code{malloc}ed.
|
| -
|
| -The companion function @code{ui_out_table_end}, described below, marks
|
| -the end of the table's output.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_table_header (struct ui_out *@var{uiout}, int @var{width}, enum ui_align @var{alignment}, const char *@var{colhdr})
|
| -@code{ui_out_table_header} provides the header information for a single
|
| -table column. You call this function several times, one each for every
|
| -column of the table, after @code{ui_out_table_begin}, but before
|
| -@code{ui_out_table_body}.
|
| -
|
| -The value of @var{width} gives the column width in characters. The
|
| -value of @var{alignment} is one of @code{left}, @code{center}, and
|
| -@code{right}, and it specifies how to align the header: left-justify,
|
| -center, or right-justify it. @var{colhdr} points to a string that
|
| -specifies the column header; the implementation copies that string, so
|
| -column header strings in @code{malloc}ed storage can be freed after the
|
| -call.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_table_body (struct ui_out *@var{uiout})
|
| -This function delimits the table header from the table body.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_table_end (struct ui_out *@var{uiout})
|
| -This function signals the end of a table's output. It should be called
|
| -after the table body has been produced by the list and field output
|
| -functions.
|
| -
|
| -There should be exactly one call to @code{ui_out_table_end} for each
|
| -call to @code{ui_out_table_begin}, otherwise the @code{ui_out} functions
|
| -will signal an internal error.
|
| -@end deftypefun
|
| -
|
| -The output of the tuples that represent the table rows must follow the
|
| -call to @code{ui_out_table_body} and precede the call to
|
| -@code{ui_out_table_end}. You build a tuple by calling
|
| -@code{ui_out_tuple_begin} and @code{ui_out_tuple_end}, with suitable
|
| -calls to functions which actually output fields between them.
|
| -
|
| -@deftypefun void ui_out_tuple_begin (struct ui_out *@var{uiout}, const char *@var{id})
|
| -This function marks the beginning of a tuple output. @var{id} points
|
| -to an optional string that identifies the tuple; it is copied by the
|
| -implementation, and so strings in @code{malloc}ed storage can be freed
|
| -after the call.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_tuple_end (struct ui_out *@var{uiout})
|
| -This function signals an end of a tuple output. There should be exactly
|
| -one call to @code{ui_out_tuple_end} for each call to
|
| -@code{ui_out_tuple_begin}, otherwise an internal @value{GDBN} error will
|
| -be signaled.
|
| -@end deftypefun
|
| -
|
| -@deftypefun {struct cleanup *} make_cleanup_ui_out_tuple_begin_end (struct ui_out *@var{uiout}, const char *@var{id})
|
| -This function first opens the tuple and then establishes a cleanup
|
| -(@pxref{Misc Guidelines, Cleanups}) to close the tuple.
|
| -It provides a convenient and correct implementation of the
|
| -non-portable@footnote{The function cast is not portable ISO C.} code sequence:
|
| -@smallexample
|
| -struct cleanup *old_cleanup;
|
| -ui_out_tuple_begin (uiout, "...");
|
| -old_cleanup = make_cleanup ((void(*)(void *)) ui_out_tuple_end,
|
| - uiout);
|
| -@end smallexample
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_list_begin (struct ui_out *@var{uiout}, const char *@var{id})
|
| -This function marks the beginning of a list output. @var{id} points to
|
| -an optional string that identifies the list; it is copied by the
|
| -implementation, and so strings in @code{malloc}ed storage can be freed
|
| -after the call.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_list_end (struct ui_out *@var{uiout})
|
| -This function signals an end of a list output. There should be exactly
|
| -one call to @code{ui_out_list_end} for each call to
|
| -@code{ui_out_list_begin}, otherwise an internal @value{GDBN} error will
|
| -be signaled.
|
| -@end deftypefun
|
| -
|
| -@deftypefun {struct cleanup *} make_cleanup_ui_out_list_begin_end (struct ui_out *@var{uiout}, const char *@var{id})
|
| -Similar to @code{make_cleanup_ui_out_tuple_begin_end}, this function
|
| -opens a list and then establishes cleanup
|
| -(@pxref{Misc Guidelines, Cleanups})
|
| -that will close the list.
|
| -@end deftypefun
|
| -
|
| -@subsection Item Output Functions
|
| -
|
| -@cindex item output functions
|
| -@cindex field output functions
|
| -@cindex data output
|
| -The functions described below produce output for the actual data
|
| -items, or fields, which contain information about the object.
|
| -
|
| -Choose the appropriate function accordingly to your particular needs.
|
| -
|
| -@deftypefun void ui_out_field_fmt (struct ui_out *@var{uiout}, char *@var{fldname}, char *@var{format}, ...)
|
| -This is the most general output function. It produces the
|
| -representation of the data in the variable-length argument list
|
| -according to formatting specifications in @var{format}, a
|
| -@code{printf}-like format string. The optional argument @var{fldname}
|
| -supplies the name of the field. The data items themselves are
|
| -supplied as additional arguments after @var{format}.
|
| -
|
| -This generic function should be used only when it is not possible to
|
| -use one of the specialized versions (see below).
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_field_int (struct ui_out *@var{uiout}, const char *@var{fldname}, int @var{value})
|
| -This function outputs a value of an @code{int} variable. It uses the
|
| -@code{"%d"} output conversion specification. @var{fldname} specifies
|
| -the name of the field.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_field_fmt_int (struct ui_out *@var{uiout}, int @var{width}, enum ui_align @var{alignment}, const char *@var{fldname}, int @var{value})
|
| -This function outputs a value of an @code{int} variable. It differs from
|
| -@code{ui_out_field_int} in that the caller specifies the desired @var{width} and @var{alignment} of the output.
|
| -@var{fldname} specifies
|
| -the name of the field.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_field_core_addr (struct ui_out *@var{uiout}, const char *@var{fldname}, struct gdbarch *@var{gdbarch}, CORE_ADDR @var{address})
|
| -This function outputs an address as appropriate for @var{gdbarch}.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_field_string (struct ui_out *@var{uiout}, const char *@var{fldname}, const char *@var{string})
|
| -This function outputs a string using the @code{"%s"} conversion
|
| -specification.
|
| -@end deftypefun
|
| -
|
| -Sometimes, there's a need to compose your output piece by piece using
|
| -functions that operate on a stream, such as @code{value_print} or
|
| -@code{fprintf_symbol_filtered}. These functions accept an argument of
|
| -the type @code{struct ui_file *}, a pointer to a @code{ui_file} object
|
| -used to store the data stream used for the output. When you use one
|
| -of these functions, you need a way to pass their results stored in a
|
| -@code{ui_file} object to the @code{ui_out} functions. To this end,
|
| -you first create a @code{ui_stream} object by calling
|
| -@code{ui_out_stream_new}, pass the @code{stream} member of that
|
| -@code{ui_stream} object to @code{value_print} and similar functions,
|
| -and finally call @code{ui_out_field_stream} to output the field you
|
| -constructed. When the @code{ui_stream} object is no longer needed,
|
| -you should destroy it and free its memory by calling
|
| -@code{ui_out_stream_delete}.
|
| -
|
| -@deftypefun {struct ui_stream *} ui_out_stream_new (struct ui_out *@var{uiout})
|
| -This function creates a new @code{ui_stream} object which uses the
|
| -same output methods as the @code{ui_out} object whose pointer is
|
| -passed in @var{uiout}. It returns a pointer to the newly created
|
| -@code{ui_stream} object.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_stream_delete (struct ui_stream *@var{streambuf})
|
| -This functions destroys a @code{ui_stream} object specified by
|
| -@var{streambuf}.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_field_stream (struct ui_out *@var{uiout}, const char *@var{fieldname}, struct ui_stream *@var{streambuf})
|
| -This function consumes all the data accumulated in
|
| -@code{streambuf->stream} and outputs it like
|
| -@code{ui_out_field_string} does. After a call to
|
| -@code{ui_out_field_stream}, the accumulated data no longer exists, but
|
| -the stream is still valid and may be used for producing more fields.
|
| -@end deftypefun
|
| -
|
| -@strong{Important:} If there is any chance that your code could bail
|
| -out before completing output generation and reaching the point where
|
| -@code{ui_out_stream_delete} is called, it is necessary to set up a
|
| -cleanup, to avoid leaking memory and other resources. Here's a
|
| -skeleton code to do that:
|
| -
|
| -@smallexample
|
| - struct ui_stream *mybuf = ui_out_stream_new (uiout);
|
| - struct cleanup *old = make_cleanup (ui_out_stream_delete, mybuf);
|
| - ...
|
| - do_cleanups (old);
|
| -@end smallexample
|
| -
|
| -If the function already has the old cleanup chain set (for other kinds
|
| -of cleanups), you just have to add your cleanup to it:
|
| -
|
| -@smallexample
|
| - mybuf = ui_out_stream_new (uiout);
|
| - make_cleanup (ui_out_stream_delete, mybuf);
|
| -@end smallexample
|
| -
|
| -Note that with cleanups in place, you should not call
|
| -@code{ui_out_stream_delete} directly, or you would attempt to free the
|
| -same buffer twice.
|
| -
|
| -@subsection Utility Output Functions
|
| -
|
| -@deftypefun void ui_out_field_skip (struct ui_out *@var{uiout}, const char *@var{fldname})
|
| -This function skips a field in a table. Use it if you have to leave
|
| -an empty field without disrupting the table alignment. The argument
|
| -@var{fldname} specifies a name for the (missing) filed.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_text (struct ui_out *@var{uiout}, const char *@var{string})
|
| -This function outputs the text in @var{string} in a way that makes it
|
| -easy to be read by humans. For example, the console implementation of
|
| -this method filters the text through a built-in pager, to prevent it
|
| -from scrolling off the visible portion of the screen.
|
| -
|
| -Use this function for printing relatively long chunks of text around
|
| -the actual field data: the text it produces is not aligned according
|
| -to the table's format. Use @code{ui_out_field_string} to output a
|
| -string field, and use @code{ui_out_message}, described below, to
|
| -output short messages.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_spaces (struct ui_out *@var{uiout}, int @var{nspaces})
|
| -This function outputs @var{nspaces} spaces. It is handy to align the
|
| -text produced by @code{ui_out_text} with the rest of the table or
|
| -list.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_message (struct ui_out *@var{uiout}, int @var{verbosity}, const char *@var{format}, ...)
|
| -This function produces a formatted message, provided that the current
|
| -verbosity level is at least as large as given by @var{verbosity}. The
|
| -current verbosity level is specified by the user with the @samp{set
|
| -verbositylevel} command.@footnote{As of this writing (April 2001),
|
| -setting verbosity level is not yet implemented, and is always returned
|
| -as zero. So calling @code{ui_out_message} with a @var{verbosity}
|
| -argument more than zero will cause the message to never be printed.}
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_wrap_hint (struct ui_out *@var{uiout}, char *@var{indent})
|
| -This function gives the console output filter (a paging filter) a hint
|
| -of where to break lines which are too long. Ignored for all other
|
| -output consumers. @var{indent}, if non-@code{NULL}, is the string to
|
| -be printed to indent the wrapped text on the next line; it must remain
|
| -accessible until the next call to @code{ui_out_wrap_hint}, or until an
|
| -explicit newline is produced by one of the other functions. If
|
| -@var{indent} is @code{NULL}, the wrapped text will not be indented.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void ui_out_flush (struct ui_out *@var{uiout})
|
| -This function flushes whatever output has been accumulated so far, if
|
| -the UI buffers output.
|
| -@end deftypefun
|
| -
|
| -
|
| -@subsection Examples of Use of @code{ui_out} functions
|
| -
|
| -@cindex using @code{ui_out} functions
|
| -@cindex @code{ui_out} functions, usage examples
|
| -This section gives some practical examples of using the @code{ui_out}
|
| -functions to generalize the old console-oriented code in
|
| -@value{GDBN}. The examples all come from functions defined on the
|
| -@file{breakpoints.c} file.
|
| -
|
| -This example, from the @code{breakpoint_1} function, shows how to
|
| -produce a table.
|
| -
|
| -The original code was:
|
| -
|
| -@smallexample
|
| - if (!found_a_breakpoint++)
|
| - @{
|
| - annotate_breakpoints_headers ();
|
| -
|
| - annotate_field (0);
|
| - printf_filtered ("Num ");
|
| - annotate_field (1);
|
| - printf_filtered ("Type ");
|
| - annotate_field (2);
|
| - printf_filtered ("Disp ");
|
| - annotate_field (3);
|
| - printf_filtered ("Enb ");
|
| - if (addressprint)
|
| - @{
|
| - annotate_field (4);
|
| - printf_filtered ("Address ");
|
| - @}
|
| - annotate_field (5);
|
| - printf_filtered ("What\n");
|
| -
|
| - annotate_breakpoints_table ();
|
| - @}
|
| -@end smallexample
|
| -
|
| -Here's the new version:
|
| -
|
| -@smallexample
|
| - nr_printable_breakpoints = @dots{};
|
| -
|
| - if (addressprint)
|
| - ui_out_table_begin (ui, 6, nr_printable_breakpoints, "BreakpointTable");
|
| - else
|
| - ui_out_table_begin (ui, 5, nr_printable_breakpoints, "BreakpointTable");
|
| -
|
| - if (nr_printable_breakpoints > 0)
|
| - annotate_breakpoints_headers ();
|
| - if (nr_printable_breakpoints > 0)
|
| - annotate_field (0);
|
| - ui_out_table_header (uiout, 3, ui_left, "number", "Num"); /* 1 */
|
| - if (nr_printable_breakpoints > 0)
|
| - annotate_field (1);
|
| - ui_out_table_header (uiout, 14, ui_left, "type", "Type"); /* 2 */
|
| - if (nr_printable_breakpoints > 0)
|
| - annotate_field (2);
|
| - ui_out_table_header (uiout, 4, ui_left, "disp", "Disp"); /* 3 */
|
| - if (nr_printable_breakpoints > 0)
|
| - annotate_field (3);
|
| - ui_out_table_header (uiout, 3, ui_left, "enabled", "Enb"); /* 4 */
|
| - if (addressprint)
|
| - @{
|
| - if (nr_printable_breakpoints > 0)
|
| - annotate_field (4);
|
| - if (print_address_bits <= 32)
|
| - ui_out_table_header (uiout, 10, ui_left, "addr", "Address");/* 5 */
|
| - else
|
| - ui_out_table_header (uiout, 18, ui_left, "addr", "Address");/* 5 */
|
| - @}
|
| - if (nr_printable_breakpoints > 0)
|
| - annotate_field (5);
|
| - ui_out_table_header (uiout, 40, ui_noalign, "what", "What"); /* 6 */
|
| - ui_out_table_body (uiout);
|
| - if (nr_printable_breakpoints > 0)
|
| - annotate_breakpoints_table ();
|
| -@end smallexample
|
| -
|
| -This example, from the @code{print_one_breakpoint} function, shows how
|
| -to produce the actual data for the table whose structure was defined
|
| -in the above example. The original code was:
|
| -
|
| -@smallexample
|
| - annotate_record ();
|
| - annotate_field (0);
|
| - printf_filtered ("%-3d ", b->number);
|
| - annotate_field (1);
|
| - if ((int)b->type > (sizeof(bptypes)/sizeof(bptypes[0]))
|
| - || ((int) b->type != bptypes[(int) b->type].type))
|
| - internal_error ("bptypes table does not describe type #%d.",
|
| - (int)b->type);
|
| - printf_filtered ("%-14s ", bptypes[(int)b->type].description);
|
| - annotate_field (2);
|
| - printf_filtered ("%-4s ", bpdisps[(int)b->disposition]);
|
| - annotate_field (3);
|
| - printf_filtered ("%-3c ", bpenables[(int)b->enable]);
|
| - @dots{}
|
| -@end smallexample
|
| -
|
| -This is the new version:
|
| -
|
| -@smallexample
|
| - annotate_record ();
|
| - ui_out_tuple_begin (uiout, "bkpt");
|
| - annotate_field (0);
|
| - ui_out_field_int (uiout, "number", b->number);
|
| - annotate_field (1);
|
| - if (((int) b->type > (sizeof (bptypes) / sizeof (bptypes[0])))
|
| - || ((int) b->type != bptypes[(int) b->type].type))
|
| - internal_error ("bptypes table does not describe type #%d.",
|
| - (int) b->type);
|
| - ui_out_field_string (uiout, "type", bptypes[(int)b->type].description);
|
| - annotate_field (2);
|
| - ui_out_field_string (uiout, "disp", bpdisps[(int)b->disposition]);
|
| - annotate_field (3);
|
| - ui_out_field_fmt (uiout, "enabled", "%c", bpenables[(int)b->enable]);
|
| - @dots{}
|
| -@end smallexample
|
| -
|
| -This example, also from @code{print_one_breakpoint}, shows how to
|
| -produce a complicated output field using the @code{print_expression}
|
| -functions which requires a stream to be passed. It also shows how to
|
| -automate stream destruction with cleanups. The original code was:
|
| -
|
| -@smallexample
|
| - annotate_field (5);
|
| - print_expression (b->exp, gdb_stdout);
|
| -@end smallexample
|
| -
|
| -The new version is:
|
| -
|
| -@smallexample
|
| - struct ui_stream *stb = ui_out_stream_new (uiout);
|
| - struct cleanup *old_chain = make_cleanup_ui_out_stream_delete (stb);
|
| - ...
|
| - annotate_field (5);
|
| - print_expression (b->exp, stb->stream);
|
| - ui_out_field_stream (uiout, "what", local_stream);
|
| -@end smallexample
|
| -
|
| -This example, also from @code{print_one_breakpoint}, shows how to use
|
| -@code{ui_out_text} and @code{ui_out_field_string}. The original code
|
| -was:
|
| -
|
| -@smallexample
|
| - annotate_field (5);
|
| - if (b->dll_pathname == NULL)
|
| - printf_filtered ("<any library> ");
|
| - else
|
| - printf_filtered ("library \"%s\" ", b->dll_pathname);
|
| -@end smallexample
|
| -
|
| -It became:
|
| -
|
| -@smallexample
|
| - annotate_field (5);
|
| - if (b->dll_pathname == NULL)
|
| - @{
|
| - ui_out_field_string (uiout, "what", "<any library>");
|
| - ui_out_spaces (uiout, 1);
|
| - @}
|
| - else
|
| - @{
|
| - ui_out_text (uiout, "library \"");
|
| - ui_out_field_string (uiout, "what", b->dll_pathname);
|
| - ui_out_text (uiout, "\" ");
|
| - @}
|
| -@end smallexample
|
| -
|
| -The following example from @code{print_one_breakpoint} shows how to
|
| -use @code{ui_out_field_int} and @code{ui_out_spaces}. The original
|
| -code was:
|
| -
|
| -@smallexample
|
| - annotate_field (5);
|
| - if (b->forked_inferior_pid != 0)
|
| - printf_filtered ("process %d ", b->forked_inferior_pid);
|
| -@end smallexample
|
| -
|
| -It became:
|
| -
|
| -@smallexample
|
| - annotate_field (5);
|
| - if (b->forked_inferior_pid != 0)
|
| - @{
|
| - ui_out_text (uiout, "process ");
|
| - ui_out_field_int (uiout, "what", b->forked_inferior_pid);
|
| - ui_out_spaces (uiout, 1);
|
| - @}
|
| -@end smallexample
|
| -
|
| -Here's an example of using @code{ui_out_field_string}. The original
|
| -code was:
|
| -
|
| -@smallexample
|
| - annotate_field (5);
|
| - if (b->exec_pathname != NULL)
|
| - printf_filtered ("program \"%s\" ", b->exec_pathname);
|
| -@end smallexample
|
| -
|
| -It became:
|
| -
|
| -@smallexample
|
| - annotate_field (5);
|
| - if (b->exec_pathname != NULL)
|
| - @{
|
| - ui_out_text (uiout, "program \"");
|
| - ui_out_field_string (uiout, "what", b->exec_pathname);
|
| - ui_out_text (uiout, "\" ");
|
| - @}
|
| -@end smallexample
|
| -
|
| -Finally, here's an example of printing an address. The original code:
|
| -
|
| -@smallexample
|
| - annotate_field (4);
|
| - printf_filtered ("%s ",
|
| - hex_string_custom ((unsigned long) b->address, 8));
|
| -@end smallexample
|
| -
|
| -It became:
|
| -
|
| -@smallexample
|
| - annotate_field (4);
|
| - ui_out_field_core_addr (uiout, "Address", b->address);
|
| -@end smallexample
|
| -
|
| -
|
| -@section Console Printing
|
| -
|
| -@section TUI
|
| -
|
| -@node libgdb
|
| -
|
| -@chapter libgdb
|
| -
|
| -@section libgdb 1.0
|
| -@cindex @code{libgdb}
|
| -@code{libgdb} 1.0 was an abortive project of years ago. The theory was
|
| -to provide an API to @value{GDBN}'s functionality.
|
| -
|
| -@section libgdb 2.0
|
| -@cindex @code{libgdb}
|
| -@code{libgdb} 2.0 is an ongoing effort to update @value{GDBN} so that is
|
| -better able to support graphical and other environments.
|
| -
|
| -Since @code{libgdb} development is on-going, its architecture is still
|
| -evolving. The following components have so far been identified:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -Observer - @file{gdb-events.h}.
|
| -@item
|
| -Builder - @file{ui-out.h}
|
| -@item
|
| -Event Loop - @file{event-loop.h}
|
| -@item
|
| -Library - @file{gdb.h}
|
| -@end itemize
|
| -
|
| -The model that ties these components together is described below.
|
| -
|
| -@section The @code{libgdb} Model
|
| -
|
| -A client of @code{libgdb} interacts with the library in two ways.
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -As an observer (using @file{gdb-events}) receiving notifications from
|
| -@code{libgdb} of any internal state changes (break point changes, run
|
| -state, etc).
|
| -@item
|
| -As a client querying @code{libgdb} (using the @file{ui-out} builder) to
|
| -obtain various status values from @value{GDBN}.
|
| -@end itemize
|
| -
|
| -Since @code{libgdb} could have multiple clients (e.g., a GUI supporting
|
| -the existing @value{GDBN} CLI), those clients must co-operate when
|
| -controlling @code{libgdb}. In particular, a client must ensure that
|
| -@code{libgdb} is idle (i.e.@: no other client is using @code{libgdb})
|
| -before responding to a @file{gdb-event} by making a query.
|
| -
|
| -@section CLI support
|
| -
|
| -At present @value{GDBN}'s CLI is very much entangled in with the core of
|
| -@code{libgdb}. Consequently, a client wishing to include the CLI in
|
| -their interface needs to carefully co-ordinate its own and the CLI's
|
| -requirements.
|
| -
|
| -It is suggested that the client set @code{libgdb} up to be bi-modal
|
| -(alternate between CLI and client query modes). The notes below sketch
|
| -out the theory:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -The client registers itself as an observer of @code{libgdb}.
|
| -@item
|
| -The client create and install @code{cli-out} builder using its own
|
| -versions of the @code{ui-file} @code{gdb_stderr}, @code{gdb_stdtarg} and
|
| -@code{gdb_stdout} streams.
|
| -@item
|
| -The client creates a separate custom @code{ui-out} builder that is only
|
| -used while making direct queries to @code{libgdb}.
|
| -@end itemize
|
| -
|
| -When the client receives input intended for the CLI, it simply passes it
|
| -along. Since the @code{cli-out} builder is installed by default, all
|
| -the CLI output in response to that command is routed (pronounced rooted)
|
| -through to the client controlled @code{gdb_stdout} et.@: al.@: streams.
|
| -At the same time, the client is kept abreast of internal changes by
|
| -virtue of being a @code{libgdb} observer.
|
| -
|
| -The only restriction on the client is that it must wait until
|
| -@code{libgdb} becomes idle before initiating any queries (using the
|
| -client's custom builder).
|
| -
|
| -@section @code{libgdb} components
|
| -
|
| -@subheading Observer - @file{gdb-events.h}
|
| -@file{gdb-events} provides the client with a very raw mechanism that can
|
| -be used to implement an observer. At present it only allows for one
|
| -observer and that observer must, internally, handle the need to delay
|
| -the processing of any event notifications until after @code{libgdb} has
|
| -finished the current command.
|
| -
|
| -@subheading Builder - @file{ui-out.h}
|
| -@file{ui-out} provides the infrastructure necessary for a client to
|
| -create a builder. That builder is then passed down to @code{libgdb}
|
| -when doing any queries.
|
| -
|
| -@subheading Event Loop - @file{event-loop.h}
|
| -@c There could be an entire section on the event-loop
|
| -@file{event-loop}, currently non-re-entrant, provides a simple event
|
| -loop. A client would need to either plug its self into this loop or,
|
| -implement a new event-loop that @value{GDBN} would use.
|
| -
|
| -The event-loop will eventually be made re-entrant. This is so that
|
| -@value{GDBN} can better handle the problem of some commands blocking
|
| -instead of returning.
|
| -
|
| -@subheading Library - @file{gdb.h}
|
| -@file{libgdb} is the most obvious component of this system. It provides
|
| -the query interface. Each function is parameterized by a @code{ui-out}
|
| -builder. The result of the query is constructed using that builder
|
| -before the query function returns.
|
| -
|
| -@node Values
|
| -@chapter Values
|
| -@section Values
|
| -
|
| -@cindex values
|
| -@cindex @code{value} structure
|
| -@value{GDBN} uses @code{struct value}, or @dfn{values}, as an internal
|
| -abstraction for the representation of a variety of inferior objects
|
| -and @value{GDBN} convenience objects.
|
| -
|
| -Values have an associated @code{struct type}, that describes a virtual
|
| -view of the raw data or object stored in or accessed through the
|
| -value.
|
| -
|
| -A value is in addition discriminated by its lvalue-ness, given its
|
| -@code{enum lval_type} enumeration type:
|
| -
|
| -@cindex @code{lval_type} enumeration, for values.
|
| -@table @code
|
| -@item @code{not_lval}
|
| -This value is not an lval. It can't be assigned to.
|
| -
|
| -@item @code{lval_memory}
|
| -This value represents an object in memory.
|
| -
|
| -@item @code{lval_register}
|
| -This value represents an object that lives in a register.
|
| -
|
| -@item @code{lval_internalvar}
|
| -Represents the value of an internal variable.
|
| -
|
| -@item @code{lval_internalvar_component}
|
| -Represents part of a @value{GDBN} internal variable. E.g., a
|
| -structure field.
|
| -
|
| -@cindex computed values
|
| -@item @code{lval_computed}
|
| -These are ``computed'' values. They allow creating specialized value
|
| -objects for specific purposes, all abstracted away from the core value
|
| -support code. The creator of such a value writes specialized
|
| -functions to handle the reading and writing to/from the value's
|
| -backend data, and optionally, a ``copy operator'' and a
|
| -``destructor''.
|
| -
|
| -Pointers to these functions are stored in a @code{struct lval_funcs}
|
| -instance (declared in @file{value.h}), and passed to the
|
| -@code{allocate_computed_value} function, as in the example below.
|
| -
|
| -@smallexample
|
| -static void
|
| -nil_value_read (struct value *v)
|
| -@{
|
| - /* This callback reads data from some backend, and stores it in V.
|
| - In this case, we always read null data. You'll want to fill in
|
| - something more interesting. */
|
| -
|
| - memset (value_contents_all_raw (v),
|
| - value_offset (v),
|
| - TYPE_LENGTH (value_type (v)));
|
| -@}
|
| -
|
| -static void
|
| -nil_value_write (struct value *v, struct value *fromval)
|
| -@{
|
| - /* Takes the data from FROMVAL and stores it in the backend of V. */
|
| -
|
| - to_oblivion (value_contents_all_raw (fromval),
|
| - value_offset (v),
|
| - TYPE_LENGTH (value_type (fromval)));
|
| -@}
|
| -
|
| -static struct lval_funcs nil_value_funcs =
|
| - @{
|
| - nil_value_read,
|
| - nil_value_write
|
| - @};
|
| -
|
| -struct value *
|
| -make_nil_value (void)
|
| -@{
|
| - struct type *type;
|
| - struct value *v;
|
| -
|
| - type = make_nils_type ();
|
| - v = allocate_computed_value (type, &nil_value_funcs, NULL);
|
| -
|
| - return v;
|
| -@}
|
| -@end smallexample
|
| -
|
| -See the implementation of the @code{$_siginfo} convenience variable in
|
| -@file{infrun.c} as a real example use of lval_computed.
|
| -
|
| -@end table
|
| -
|
| -@node Stack Frames
|
| -@chapter Stack Frames
|
| -
|
| -@cindex frame
|
| -@cindex call stack frame
|
| -A frame is a construct that @value{GDBN} uses to keep track of calling
|
| -and called functions.
|
| -
|
| -@cindex unwind frame
|
| -@value{GDBN}'s frame model, a fresh design, was implemented with the
|
| -need to support @sc{dwarf}'s Call Frame Information in mind. In fact,
|
| -the term ``unwind'' is taken directly from that specification.
|
| -Developers wishing to learn more about unwinders, are encouraged to
|
| -read the @sc{dwarf} specification, available from
|
| -@url{http://www.dwarfstd.org}.
|
| -
|
| -@findex frame_register_unwind
|
| -@findex get_frame_register
|
| -@value{GDBN}'s model is that you find a frame's registers by
|
| -``unwinding'' them from the next younger frame. That is,
|
| -@samp{get_frame_register} which returns the value of a register in
|
| -frame #1 (the next-to-youngest frame), is implemented by calling frame
|
| -#0's @code{frame_register_unwind} (the youngest frame). But then the
|
| -obvious question is: how do you access the registers of the youngest
|
| -frame itself?
|
| -
|
| -@cindex sentinel frame
|
| -@findex get_frame_type
|
| -@vindex SENTINEL_FRAME
|
| -To answer this question, @value{GDBN} has the @dfn{sentinel} frame, the
|
| -``-1st'' frame. Unwinding registers from the sentinel frame gives you
|
| -the current values of the youngest real frame's registers. If @var{f}
|
| -is a sentinel frame, then @code{get_frame_type (@var{f}) @equiv{}
|
| -SENTINEL_FRAME}.
|
| -
|
| -@section Selecting an Unwinder
|
| -
|
| -@findex frame_unwind_prepend_unwinder
|
| -@findex frame_unwind_append_unwinder
|
| -The architecture registers a list of frame unwinders (@code{struct
|
| -frame_unwind}), using the functions
|
| -@code{frame_unwind_prepend_unwinder} and
|
| -@code{frame_unwind_append_unwinder}. Each unwinder includes a
|
| -sniffer. Whenever @value{GDBN} needs to unwind a frame (to fetch the
|
| -previous frame's registers or the current frame's ID), it calls
|
| -registered sniffers in order to find one which recognizes the frame.
|
| -The first time a sniffer returns non-zero, the corresponding unwinder
|
| -is assigned to the frame.
|
| -
|
| -@section Unwinding the Frame ID
|
| -@cindex frame ID
|
| -
|
| -Every frame has an associated ID, of type @code{struct frame_id}.
|
| -The ID includes the stack base and function start address for
|
| -the frame. The ID persists through the entire life of the frame,
|
| -including while other called frames are running; it is used to
|
| -locate an appropriate @code{struct frame_info} from the cache.
|
| -
|
| -Every time the inferior stops, and at various other times, the frame
|
| -cache is flushed. Because of this, parts of @value{GDBN} which need
|
| -to keep track of individual frames cannot use pointers to @code{struct
|
| -frame_info}. A frame ID provides a stable reference to a frame, even
|
| -when the unwinder must be run again to generate a new @code{struct
|
| -frame_info} for the same frame.
|
| -
|
| -The frame's unwinder's @code{this_id} method is called to find the ID.
|
| -Note that this is different from register unwinding, where the next
|
| -frame's @code{prev_register} is called to unwind this frame's
|
| -registers.
|
| -
|
| -Both stack base and function address are required to identify the
|
| -frame, because a recursive function has the same function address for
|
| -two consecutive frames and a leaf function may have the same stack
|
| -address as its caller. On some platforms, a third address is part of
|
| -the ID to further disambiguate frames---for instance, on IA-64
|
| -the separate register stack address is included in the ID.
|
| -
|
| -An invalid frame ID (@code{outer_frame_id}) returned from the
|
| -@code{this_id} method means to stop unwinding after this frame.
|
| -
|
| -@code{null_frame_id} is another invalid frame ID which should be used
|
| -when there is no frame. For instance, certain breakpoints are attached
|
| -to a specific frame, and that frame is identified through its frame ID
|
| -(we use this to implement the "finish" command). Using
|
| -@code{null_frame_id} as the frame ID for a given breakpoint means
|
| -that the breakpoint is not specific to any frame. The @code{this_id}
|
| -method should never return @code{null_frame_id}.
|
| -
|
| -@section Unwinding Registers
|
| -
|
| -Each unwinder includes a @code{prev_register} method. This method
|
| -takes a frame, an associated cache pointer, and a register number.
|
| -It returns a @code{struct value *} describing the requested register,
|
| -as saved by this frame. This is the value of the register that is
|
| -current in this frame's caller.
|
| -
|
| -The returned value must have the same type as the register. It may
|
| -have any lvalue type. In most circumstances one of these routines
|
| -will generate the appropriate value:
|
| -
|
| -@table @code
|
| -@item frame_unwind_got_optimized
|
| -@findex frame_unwind_got_optimized
|
| -This register was not saved.
|
| -
|
| -@item frame_unwind_got_register
|
| -@findex frame_unwind_got_register
|
| -This register was copied into another register in this frame. This
|
| -is also used for unchanged registers; they are ``copied'' into the
|
| -same register.
|
| -
|
| -@item frame_unwind_got_memory
|
| -@findex frame_unwind_got_memory
|
| -This register was saved in memory.
|
| -
|
| -@item frame_unwind_got_constant
|
| -@findex frame_unwind_got_constant
|
| -This register was not saved, but the unwinder can compute the previous
|
| -value some other way.
|
| -
|
| -@item frame_unwind_got_address
|
| -@findex frame_unwind_got_address
|
| -Same as @code{frame_unwind_got_constant}, except that the value is a target
|
| -address. This is frequently used for the stack pointer, which is not
|
| -explicitly saved but has a known offset from this frame's stack
|
| -pointer. For architectures with a flat unified address space, this is
|
| -generally the same as @code{frame_unwind_got_constant}.
|
| -@end table
|
| -
|
| -@node Symbol Handling
|
| -
|
| -@chapter Symbol Handling
|
| -
|
| -Symbols are a key part of @value{GDBN}'s operation. Symbols include
|
| -variables, functions, and types.
|
| -
|
| -Symbol information for a large program can be truly massive, and
|
| -reading of symbol information is one of the major performance
|
| -bottlenecks in @value{GDBN}; it can take many minutes to process it
|
| -all. Studies have shown that nearly all the time spent is
|
| -computational, rather than file reading.
|
| -
|
| -One of the ways for @value{GDBN} to provide a good user experience is
|
| -to start up quickly, taking no more than a few seconds. It is simply
|
| -not possible to process all of a program's debugging info in that
|
| -time, and so we attempt to handle symbols incrementally. For instance,
|
| -we create @dfn{partial symbol tables} consisting of only selected
|
| -symbols, and only expand them to full symbol tables when necessary.
|
| -
|
| -@section Symbol Reading
|
| -
|
| -@cindex symbol reading
|
| -@cindex reading of symbols
|
| -@cindex symbol files
|
| -@value{GDBN} reads symbols from @dfn{symbol files}. The usual symbol
|
| -file is the file containing the program which @value{GDBN} is
|
| -debugging. @value{GDBN} can be directed to use a different file for
|
| -symbols (with the @samp{symbol-file} command), and it can also read
|
| -more symbols via the @samp{add-file} and @samp{load} commands. In
|
| -addition, it may bring in more symbols while loading shared
|
| -libraries.
|
| -
|
| -@findex find_sym_fns
|
| -Symbol files are initially opened by code in @file{symfile.c} using
|
| -the BFD library (@pxref{Support Libraries}). BFD identifies the type
|
| -of the file by examining its header. @code{find_sym_fns} then uses
|
| -this identification to locate a set of symbol-reading functions.
|
| -
|
| -@findex add_symtab_fns
|
| -@cindex @code{sym_fns} structure
|
| -@cindex adding a symbol-reading module
|
| -Symbol-reading modules identify themselves to @value{GDBN} by calling
|
| -@code{add_symtab_fns} during their module initialization. The argument
|
| -to @code{add_symtab_fns} is a @code{struct sym_fns} which contains the
|
| -name (or name prefix) of the symbol format, the length of the prefix,
|
| -and pointers to four functions. These functions are called at various
|
| -times to process symbol files whose identification matches the specified
|
| -prefix.
|
| -
|
| -The functions supplied by each module are:
|
| -
|
| -@table @code
|
| -@item @var{xyz}_symfile_init(struct sym_fns *sf)
|
| -
|
| -@cindex secondary symbol file
|
| -Called from @code{symbol_file_add} when we are about to read a new
|
| -symbol file. This function should clean up any internal state (possibly
|
| -resulting from half-read previous files, for example) and prepare to
|
| -read a new symbol file. Note that the symbol file which we are reading
|
| -might be a new ``main'' symbol file, or might be a secondary symbol file
|
| -whose symbols are being added to the existing symbol table.
|
| -
|
| -The argument to @code{@var{xyz}_symfile_init} is a newly allocated
|
| -@code{struct sym_fns} whose @code{bfd} field contains the BFD for the
|
| -new symbol file being read. Its @code{private} field has been zeroed,
|
| -and can be modified as desired. Typically, a struct of private
|
| -information will be @code{malloc}'d, and a pointer to it will be placed
|
| -in the @code{private} field.
|
| -
|
| -There is no result from @code{@var{xyz}_symfile_init}, but it can call
|
| -@code{error} if it detects an unavoidable problem.
|
| -
|
| -@item @var{xyz}_new_init()
|
| -
|
| -Called from @code{symbol_file_add} when discarding existing symbols.
|
| -This function needs only handle the symbol-reading module's internal
|
| -state; the symbol table data structures visible to the rest of
|
| -@value{GDBN} will be discarded by @code{symbol_file_add}. It has no
|
| -arguments and no result. It may be called after
|
| -@code{@var{xyz}_symfile_init}, if a new symbol table is being read, or
|
| -may be called alone if all symbols are simply being discarded.
|
| -
|
| -@item @var{xyz}_symfile_read(struct sym_fns *sf, CORE_ADDR addr, int mainline)
|
| -
|
| -Called from @code{symbol_file_add} to actually read the symbols from a
|
| -symbol-file into a set of psymtabs or symtabs.
|
| -
|
| -@code{sf} points to the @code{struct sym_fns} originally passed to
|
| -@code{@var{xyz}_sym_init} for possible initialization. @code{addr} is
|
| -the offset between the file's specified start address and its true
|
| -address in memory. @code{mainline} is 1 if this is the main symbol
|
| -table being read, and 0 if a secondary symbol file (e.g., shared library
|
| -or dynamically loaded file) is being read.@refill
|
| -@end table
|
| -
|
| -In addition, if a symbol-reading module creates psymtabs when
|
| -@var{xyz}_symfile_read is called, these psymtabs will contain a pointer
|
| -to a function @code{@var{xyz}_psymtab_to_symtab}, which can be called
|
| -from any point in the @value{GDBN} symbol-handling code.
|
| -
|
| -@table @code
|
| -@item @var{xyz}_psymtab_to_symtab (struct partial_symtab *pst)
|
| -
|
| -Called from @code{psymtab_to_symtab} (or the @code{PSYMTAB_TO_SYMTAB} macro) if
|
| -the psymtab has not already been read in and had its @code{pst->symtab}
|
| -pointer set. The argument is the psymtab to be fleshed-out into a
|
| -symtab. Upon return, @code{pst->readin} should have been set to 1, and
|
| -@code{pst->symtab} should contain a pointer to the new corresponding symtab, or
|
| -zero if there were no symbols in that part of the symbol file.
|
| -@end table
|
| -
|
| -@section Partial Symbol Tables
|
| -
|
| -@value{GDBN} has three types of symbol tables:
|
| -
|
| -@itemize @bullet
|
| -@cindex full symbol table
|
| -@cindex symtabs
|
| -@item
|
| -Full symbol tables (@dfn{symtabs}). These contain the main
|
| -information about symbols and addresses.
|
| -
|
| -@cindex psymtabs
|
| -@item
|
| -Partial symbol tables (@dfn{psymtabs}). These contain enough
|
| -information to know when to read the corresponding part of the full
|
| -symbol table.
|
| -
|
| -@cindex minimal symbol table
|
| -@cindex minsymtabs
|
| -@item
|
| -Minimal symbol tables (@dfn{msymtabs}). These contain information
|
| -gleaned from non-debugging symbols.
|
| -@end itemize
|
| -
|
| -@cindex partial symbol table
|
| -This section describes partial symbol tables.
|
| -
|
| -A psymtab is constructed by doing a very quick pass over an executable
|
| -file's debugging information. Small amounts of information are
|
| -extracted---enough to identify which parts of the symbol table will
|
| -need to be re-read and fully digested later, when the user needs the
|
| -information. The speed of this pass causes @value{GDBN} to start up very
|
| -quickly. Later, as the detailed rereading occurs, it occurs in small
|
| -pieces, at various times, and the delay therefrom is mostly invisible to
|
| -the user.
|
| -@c (@xref{Symbol Reading}.)
|
| -
|
| -The symbols that show up in a file's psymtab should be, roughly, those
|
| -visible to the debugger's user when the program is not running code from
|
| -that file. These include external symbols and types, static symbols and
|
| -types, and @code{enum} values declared at file scope.
|
| -
|
| -The psymtab also contains the range of instruction addresses that the
|
| -full symbol table would represent.
|
| -
|
| -@cindex finding a symbol
|
| -@cindex symbol lookup
|
| -The idea is that there are only two ways for the user (or much of the
|
| -code in the debugger) to reference a symbol:
|
| -
|
| -@itemize @bullet
|
| -@findex find_pc_function
|
| -@findex find_pc_line
|
| -@item
|
| -By its address (e.g., execution stops at some address which is inside a
|
| -function in this file). The address will be noticed to be in the
|
| -range of this psymtab, and the full symtab will be read in.
|
| -@code{find_pc_function}, @code{find_pc_line}, and other
|
| -@code{find_pc_@dots{}} functions handle this.
|
| -
|
| -@cindex lookup_symbol
|
| -@item
|
| -By its name
|
| -(e.g., the user asks to print a variable, or set a breakpoint on a
|
| -function). Global names and file-scope names will be found in the
|
| -psymtab, which will cause the symtab to be pulled in. Local names will
|
| -have to be qualified by a global name, or a file-scope name, in which
|
| -case we will have already read in the symtab as we evaluated the
|
| -qualifier. Or, a local symbol can be referenced when we are ``in'' a
|
| -local scope, in which case the first case applies. @code{lookup_symbol}
|
| -does most of the work here.
|
| -@end itemize
|
| -
|
| -The only reason that psymtabs exist is to cause a symtab to be read in
|
| -at the right moment. Any symbol that can be elided from a psymtab,
|
| -while still causing that to happen, should not appear in it. Since
|
| -psymtabs don't have the idea of scope, you can't put local symbols in
|
| -them anyway. Psymtabs don't have the idea of the type of a symbol,
|
| -either, so types need not appear, unless they will be referenced by
|
| -name.
|
| -
|
| -It is a bug for @value{GDBN} to behave one way when only a psymtab has
|
| -been read, and another way if the corresponding symtab has been read
|
| -in. Such bugs are typically caused by a psymtab that does not contain
|
| -all the visible symbols, or which has the wrong instruction address
|
| -ranges.
|
| -
|
| -The psymtab for a particular section of a symbol file (objfile) could be
|
| -thrown away after the symtab has been read in. The symtab should always
|
| -be searched before the psymtab, so the psymtab will never be used (in a
|
| -bug-free environment). Currently, psymtabs are allocated on an obstack,
|
| -and all the psymbols themselves are allocated in a pair of large arrays
|
| -on an obstack, so there is little to be gained by trying to free them
|
| -unless you want to do a lot more work.
|
| -
|
| -Whether or not psymtabs are created depends on the objfile's symbol
|
| -reader. The core of @value{GDBN} hides the details of partial symbols
|
| -and partial symbol tables behind a set of function pointers known as
|
| -the @dfn{quick symbol functions}. These are documented in
|
| -@file{symfile.h}.
|
| -
|
| -@section Types
|
| -
|
| -@unnumberedsubsec Fundamental Types (e.g., @code{FT_VOID}, @code{FT_BOOLEAN}).
|
| -
|
| -@cindex fundamental types
|
| -These are the fundamental types that @value{GDBN} uses internally. Fundamental
|
| -types from the various debugging formats (stabs, ELF, etc) are mapped
|
| -into one of these. They are basically a union of all fundamental types
|
| -that @value{GDBN} knows about for all the languages that @value{GDBN}
|
| -knows about.
|
| -
|
| -@unnumberedsubsec Type Codes (e.g., @code{TYPE_CODE_PTR}, @code{TYPE_CODE_ARRAY}).
|
| -
|
| -@cindex type codes
|
| -Each time @value{GDBN} builds an internal type, it marks it with one
|
| -of these types. The type may be a fundamental type, such as
|
| -@code{TYPE_CODE_INT}, or a derived type, such as @code{TYPE_CODE_PTR}
|
| -which is a pointer to another type. Typically, several @code{FT_*}
|
| -types map to one @code{TYPE_CODE_*} type, and are distinguished by
|
| -other members of the type struct, such as whether the type is signed
|
| -or unsigned, and how many bits it uses.
|
| -
|
| -@unnumberedsubsec Builtin Types (e.g., @code{builtin_type_void}, @code{builtin_type_char}).
|
| -
|
| -These are instances of type structs that roughly correspond to
|
| -fundamental types and are created as global types for @value{GDBN} to
|
| -use for various ugly historical reasons. We eventually want to
|
| -eliminate these. Note for example that @code{builtin_type_int}
|
| -initialized in @file{gdbtypes.c} is basically the same as a
|
| -@code{TYPE_CODE_INT} type that is initialized in @file{c-lang.c} for
|
| -an @code{FT_INTEGER} fundamental type. The difference is that the
|
| -@code{builtin_type} is not associated with any particular objfile, and
|
| -only one instance exists, while @file{c-lang.c} builds as many
|
| -@code{TYPE_CODE_INT} types as needed, with each one associated with
|
| -some particular objfile.
|
| -
|
| -@section Object File Formats
|
| -@cindex object file formats
|
| -
|
| -@subsection a.out
|
| -
|
| -@cindex @code{a.out} format
|
| -The @code{a.out} format is the original file format for Unix. It
|
| -consists of three sections: @code{text}, @code{data}, and @code{bss},
|
| -which are for program code, initialized data, and uninitialized data,
|
| -respectively.
|
| -
|
| -The @code{a.out} format is so simple that it doesn't have any reserved
|
| -place for debugging information. (Hey, the original Unix hackers used
|
| -@samp{adb}, which is a machine-language debugger!) The only debugging
|
| -format for @code{a.out} is stabs, which is encoded as a set of normal
|
| -symbols with distinctive attributes.
|
| -
|
| -The basic @code{a.out} reader is in @file{dbxread.c}.
|
| -
|
| -@subsection COFF
|
| -
|
| -@cindex COFF format
|
| -The COFF format was introduced with System V Release 3 (SVR3) Unix.
|
| -COFF files may have multiple sections, each prefixed by a header. The
|
| -number of sections is limited.
|
| -
|
| -The COFF specification includes support for debugging. Although this
|
| -was a step forward, the debugging information was woefully limited.
|
| -For instance, it was not possible to represent code that came from an
|
| -included file. GNU's COFF-using configs often use stabs-type info,
|
| -encapsulated in special sections.
|
| -
|
| -The COFF reader is in @file{coffread.c}.
|
| -
|
| -@subsection ECOFF
|
| -
|
| -@cindex ECOFF format
|
| -ECOFF is an extended COFF originally introduced for Mips and Alpha
|
| -workstations.
|
| -
|
| -The basic ECOFF reader is in @file{mipsread.c}.
|
| -
|
| -@subsection XCOFF
|
| -
|
| -@cindex XCOFF format
|
| -The IBM RS/6000 running AIX uses an object file format called XCOFF.
|
| -The COFF sections, symbols, and line numbers are used, but debugging
|
| -symbols are @code{dbx}-style stabs whose strings are located in the
|
| -@code{.debug} section (rather than the string table). For more
|
| -information, see @ref{Top,,,stabs,The Stabs Debugging Format}.
|
| -
|
| -The shared library scheme has a clean interface for figuring out what
|
| -shared libraries are in use, but the catch is that everything which
|
| -refers to addresses (symbol tables and breakpoints at least) needs to be
|
| -relocated for both shared libraries and the main executable. At least
|
| -using the standard mechanism this can only be done once the program has
|
| -been run (or the core file has been read).
|
| -
|
| -@subsection PE
|
| -
|
| -@cindex PE-COFF format
|
| -Windows 95 and NT use the PE (@dfn{Portable Executable}) format for their
|
| -executables. PE is basically COFF with additional headers.
|
| -
|
| -While BFD includes special PE support, @value{GDBN} needs only the basic
|
| -COFF reader.
|
| -
|
| -@subsection ELF
|
| -
|
| -@cindex ELF format
|
| -The ELF format came with System V Release 4 (SVR4) Unix. ELF is
|
| -similar to COFF in being organized into a number of sections, but it
|
| -removes many of COFF's limitations. Debugging info may be either stabs
|
| -encapsulated in ELF sections, or more commonly these days, DWARF.
|
| -
|
| -The basic ELF reader is in @file{elfread.c}.
|
| -
|
| -@subsection SOM
|
| -
|
| -@cindex SOM format
|
| -SOM is HP's object file and debug format (not to be confused with IBM's
|
| -SOM, which is a cross-language ABI).
|
| -
|
| -The SOM reader is in @file{somread.c}.
|
| -
|
| -@section Debugging File Formats
|
| -
|
| -This section describes characteristics of debugging information that
|
| -are independent of the object file format.
|
| -
|
| -@subsection stabs
|
| -
|
| -@cindex stabs debugging info
|
| -@code{stabs} started out as special symbols within the @code{a.out}
|
| -format. Since then, it has been encapsulated into other file
|
| -formats, such as COFF and ELF.
|
| -
|
| -While @file{dbxread.c} does some of the basic stab processing,
|
| -including for encapsulated versions, @file{stabsread.c} does
|
| -the real work.
|
| -
|
| -@subsection COFF
|
| -
|
| -@cindex COFF debugging info
|
| -The basic COFF definition includes debugging information. The level
|
| -of support is minimal and non-extensible, and is not often used.
|
| -
|
| -@subsection Mips debug (Third Eye)
|
| -
|
| -@cindex ECOFF debugging info
|
| -ECOFF includes a definition of a special debug format.
|
| -
|
| -The file @file{mdebugread.c} implements reading for this format.
|
| -
|
| -@c mention DWARF 1 as a formerly-supported format
|
| -
|
| -@subsection DWARF 2
|
| -
|
| -@cindex DWARF 2 debugging info
|
| -DWARF 2 is an improved but incompatible version of DWARF 1.
|
| -
|
| -The DWARF 2 reader is in @file{dwarf2read.c}.
|
| -
|
| -@subsection Compressed DWARF 2
|
| -
|
| -@cindex Compressed DWARF 2 debugging info
|
| -Compressed DWARF 2 is not technically a separate debugging format, but
|
| -merely DWARF 2 debug information that has been compressed. In this
|
| -format, every object-file section holding DWARF 2 debugging
|
| -information is compressed and prepended with a header. (The section
|
| -is also typically renamed, so a section called @code{.debug_info} in a
|
| -DWARF 2 binary would be called @code{.zdebug_info} in a compressed
|
| -DWARF 2 binary.) The header is 12 bytes long:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -4 bytes: the literal string ``ZLIB''
|
| -@item
|
| -8 bytes: the uncompressed size of the section, in big-endian byte
|
| -order.
|
| -@end itemize
|
| -
|
| -The same reader is used for both compressed an normal DWARF 2 info.
|
| -Section decompression is done in @code{zlib_decompress_section} in
|
| -@file{dwarf2read.c}.
|
| -
|
| -@subsection DWARF 3
|
| -
|
| -@cindex DWARF 3 debugging info
|
| -DWARF 3 is an improved version of DWARF 2.
|
| -
|
| -@subsection SOM
|
| -
|
| -@cindex SOM debugging info
|
| -Like COFF, the SOM definition includes debugging information.
|
| -
|
| -@section Adding a New Symbol Reader to @value{GDBN}
|
| -
|
| -@cindex adding debugging info reader
|
| -If you are using an existing object file format (@code{a.out}, COFF, ELF, etc),
|
| -there is probably little to be done.
|
| -
|
| -If you need to add a new object file format, you must first add it to
|
| -BFD. This is beyond the scope of this document.
|
| -
|
| -You must then arrange for the BFD code to provide access to the
|
| -debugging symbols. Generally @value{GDBN} will have to call swapping
|
| -routines from BFD and a few other BFD internal routines to locate the
|
| -debugging information. As much as possible, @value{GDBN} should not
|
| -depend on the BFD internal data structures.
|
| -
|
| -For some targets (e.g., COFF), there is a special transfer vector used
|
| -to call swapping routines, since the external data structures on various
|
| -platforms have different sizes and layouts. Specialized routines that
|
| -will only ever be implemented by one object file format may be called
|
| -directly. This interface should be described in a file
|
| -@file{bfd/lib@var{xyz}.h}, which is included by @value{GDBN}.
|
| -
|
| -@section Memory Management for Symbol Files
|
| -
|
| -Most memory associated with a loaded symbol file is stored on
|
| -its @code{objfile_obstack}. This includes symbols, types,
|
| -namespace data, and other information produced by the symbol readers.
|
| -
|
| -Because this data lives on the objfile's obstack, it is automatically
|
| -released when the objfile is unloaded or reloaded. Therefore one
|
| -objfile must not reference symbol or type data from another objfile;
|
| -they could be unloaded at different times.
|
| -
|
| -User convenience variables, et cetera, have associated types. Normally
|
| -these types live in the associated objfile. However, when the objfile
|
| -is unloaded, those types are deep copied to global memory, so that
|
| -the values of the user variables and history items are not lost.
|
| -
|
| -
|
| -@node Language Support
|
| -
|
| -@chapter Language Support
|
| -
|
| -@cindex language support
|
| -@value{GDBN}'s language support is mainly driven by the symbol reader,
|
| -although it is possible for the user to set the source language
|
| -manually.
|
| -
|
| -@value{GDBN} chooses the source language by looking at the extension
|
| -of the file recorded in the debug info; @file{.c} means C, @file{.f}
|
| -means Fortran, etc. It may also use a special-purpose language
|
| -identifier if the debug format supports it, like with DWARF.
|
| -
|
| -@section Adding a Source Language to @value{GDBN}
|
| -
|
| -@cindex adding source language
|
| -To add other languages to @value{GDBN}'s expression parser, follow the
|
| -following steps:
|
| -
|
| -@table @emph
|
| -@item Create the expression parser.
|
| -
|
| -@cindex expression parser
|
| -This should reside in a file @file{@var{lang}-exp.y}. Routines for
|
| -building parsed expressions into a @code{union exp_element} list are in
|
| -@file{parse.c}.
|
| -
|
| -@cindex language parser
|
| -Since we can't depend upon everyone having Bison, and YACC produces
|
| -parsers that define a bunch of global names, the following lines
|
| -@strong{must} be included at the top of the YACC parser, to prevent the
|
| -various parsers from defining the same global names:
|
| -
|
| -@smallexample
|
| -#define yyparse @var{lang}_parse
|
| -#define yylex @var{lang}_lex
|
| -#define yyerror @var{lang}_error
|
| -#define yylval @var{lang}_lval
|
| -#define yychar @var{lang}_char
|
| -#define yydebug @var{lang}_debug
|
| -#define yypact @var{lang}_pact
|
| -#define yyr1 @var{lang}_r1
|
| -#define yyr2 @var{lang}_r2
|
| -#define yydef @var{lang}_def
|
| -#define yychk @var{lang}_chk
|
| -#define yypgo @var{lang}_pgo
|
| -#define yyact @var{lang}_act
|
| -#define yyexca @var{lang}_exca
|
| -#define yyerrflag @var{lang}_errflag
|
| -#define yynerrs @var{lang}_nerrs
|
| -@end smallexample
|
| -
|
| -At the bottom of your parser, define a @code{struct language_defn} and
|
| -initialize it with the right values for your language. Define an
|
| -@code{initialize_@var{lang}} routine and have it call
|
| -@samp{add_language(@var{lang}_language_defn)} to tell the rest of @value{GDBN}
|
| -that your language exists. You'll need some other supporting variables
|
| -and functions, which will be used via pointers from your
|
| -@code{@var{lang}_language_defn}. See the declaration of @code{struct
|
| -language_defn} in @file{language.h}, and the other @file{*-exp.y} files,
|
| -for more information.
|
| -
|
| -@item Add any evaluation routines, if necessary
|
| -
|
| -@cindex expression evaluation routines
|
| -@findex evaluate_subexp
|
| -@findex prefixify_subexp
|
| -@findex length_of_subexp
|
| -If you need new opcodes (that represent the operations of the language),
|
| -add them to the enumerated type in @file{expression.h}. Add support
|
| -code for these operations in the @code{evaluate_subexp} function
|
| -defined in the file @file{eval.c}. Add cases
|
| -for new opcodes in two functions from @file{parse.c}:
|
| -@code{prefixify_subexp} and @code{length_of_subexp}. These compute
|
| -the number of @code{exp_element}s that a given operation takes up.
|
| -
|
| -@item Update some existing code
|
| -
|
| -Add an enumerated identifier for your language to the enumerated type
|
| -@code{enum language} in @file{defs.h}.
|
| -
|
| -Update the routines in @file{language.c} so your language is included.
|
| -These routines include type predicates and such, which (in some cases)
|
| -are language dependent. If your language does not appear in the switch
|
| -statement, an error is reported.
|
| -
|
| -@vindex current_language
|
| -Also included in @file{language.c} is the code that updates the variable
|
| -@code{current_language}, and the routines that translate the
|
| -@code{language_@var{lang}} enumerated identifier into a printable
|
| -string.
|
| -
|
| -@findex _initialize_language
|
| -Update the function @code{_initialize_language} to include your
|
| -language. This function picks the default language upon startup, so is
|
| -dependent upon which languages that @value{GDBN} is built for.
|
| -
|
| -@findex allocate_symtab
|
| -Update @code{allocate_symtab} in @file{symfile.c} and/or symbol-reading
|
| -code so that the language of each symtab (source file) is set properly.
|
| -This is used to determine the language to use at each stack frame level.
|
| -Currently, the language is set based upon the extension of the source
|
| -file. If the language can be better inferred from the symbol
|
| -information, please set the language of the symtab in the symbol-reading
|
| -code.
|
| -
|
| -@findex print_subexp
|
| -@findex op_print_tab
|
| -Add helper code to @code{print_subexp} (in @file{expprint.c}) to handle any new
|
| -expression opcodes you have added to @file{expression.h}. Also, add the
|
| -printed representations of your operators to @code{op_print_tab}.
|
| -
|
| -@item Add a place of call
|
| -
|
| -@findex parse_exp_1
|
| -Add a call to @code{@var{lang}_parse()} and @code{@var{lang}_error} in
|
| -@code{parse_exp_1} (defined in @file{parse.c}).
|
| -
|
| -@item Edit @file{Makefile.in}
|
| -
|
| -Add dependencies in @file{Makefile.in}. Make sure you update the macro
|
| -variables such as @code{HFILES} and @code{OBJS}, otherwise your code may
|
| -not get linked in, or, worse yet, it may not get @code{tar}red into the
|
| -distribution!
|
| -@end table
|
| -
|
| -
|
| -@node Host Definition
|
| -
|
| -@chapter Host Definition
|
| -
|
| -With the advent of Autoconf, it's rarely necessary to have host
|
| -definition machinery anymore. The following information is provided,
|
| -mainly, as an historical reference.
|
| -
|
| -@section Adding a New Host
|
| -
|
| -@cindex adding a new host
|
| -@cindex host, adding
|
| -@value{GDBN}'s host configuration support normally happens via Autoconf.
|
| -New host-specific definitions should not be needed. Older hosts
|
| -@value{GDBN} still use the host-specific definitions and files listed
|
| -below, but these mostly exist for historical reasons, and will
|
| -eventually disappear.
|
| -
|
| -@table @file
|
| -@item gdb/config/@var{arch}/@var{xyz}.mh
|
| -This file is a Makefile fragment that once contained both host and
|
| -native configuration information (@pxref{Native Debugging}) for the
|
| -machine @var{xyz}. The host configuration information is now handled
|
| -by Autoconf.
|
| -
|
| -Host configuration information included definitions for @code{CC},
|
| -@code{SYSV_DEFINE}, @code{XM_CFLAGS}, @code{XM_ADD_FILES},
|
| -@code{XM_CLIBS}, @code{XM_CDEPS}, etc.; see @file{Makefile.in}.
|
| -
|
| -New host-only configurations do not need this file.
|
| -
|
| -@end table
|
| -
|
| -(Files named @file{gdb/config/@var{arch}/xm-@var{xyz}.h} were once
|
| -used to define host-specific macros, but were no longer needed and
|
| -have all been removed.)
|
| -
|
| -@subheading Generic Host Support Files
|
| -
|
| -@cindex generic host support
|
| -There are some ``generic'' versions of routines that can be used by
|
| -various systems.
|
| -
|
| -@table @file
|
| -@cindex remote debugging support
|
| -@cindex serial line support
|
| -@item ser-unix.c
|
| -This contains serial line support for Unix systems. It is included by
|
| -default on all Unix-like hosts.
|
| -
|
| -@item ser-pipe.c
|
| -This contains serial pipe support for Unix systems. It is included by
|
| -default on all Unix-like hosts.
|
| -
|
| -@item ser-mingw.c
|
| -This contains serial line support for 32-bit programs running under
|
| -Windows using MinGW.
|
| -
|
| -@item ser-go32.c
|
| -This contains serial line support for 32-bit programs running under DOS,
|
| -using the DJGPP (a.k.a.@: GO32) execution environment.
|
| -
|
| -@cindex TCP remote support
|
| -@item ser-tcp.c
|
| -This contains generic TCP support using sockets. It is included by
|
| -default on all Unix-like hosts and with MinGW.
|
| -@end table
|
| -
|
| -@section Host Conditionals
|
| -
|
| -When @value{GDBN} is configured and compiled, various macros are
|
| -defined or left undefined, to control compilation based on the
|
| -attributes of the host system. While formerly they could be set in
|
| -host-specific header files, at present they can be changed only by
|
| -setting @code{CFLAGS} when building, or by editing the source code.
|
| -
|
| -These macros and their meanings (or if the meaning is not documented
|
| -here, then one of the source files where they are used is indicated)
|
| -are:
|
| -
|
| -@ftable @code
|
| -@item @value{GDBN}INIT_FILENAME
|
| -The default name of @value{GDBN}'s initialization file (normally
|
| -@file{.gdbinit}).
|
| -
|
| -@item SIGWINCH_HANDLER
|
| -If your host defines @code{SIGWINCH}, you can define this to be the name
|
| -of a function to be called if @code{SIGWINCH} is received.
|
| -
|
| -@item SIGWINCH_HANDLER_BODY
|
| -Define this to expand into code that will define the function named by
|
| -the expansion of @code{SIGWINCH_HANDLER}.
|
| -
|
| -@item CRLF_SOURCE_FILES
|
| -@cindex DOS text files
|
| -Define this if host files use @code{\r\n} rather than @code{\n} as a
|
| -line terminator. This will cause source file listings to omit @code{\r}
|
| -characters when printing and it will allow @code{\r\n} line endings of files
|
| -which are ``sourced'' by gdb. It must be possible to open files in binary
|
| -mode using @code{O_BINARY} or, for fopen, @code{"rb"}.
|
| -
|
| -@item DEFAULT_PROMPT
|
| -@cindex prompt
|
| -The default value of the prompt string (normally @code{"(gdb) "}).
|
| -
|
| -@item DEV_TTY
|
| -@cindex terminal device
|
| -The name of the generic TTY device, defaults to @code{"/dev/tty"}.
|
| -
|
| -@item ISATTY
|
| -Substitute for isatty, if not available.
|
| -
|
| -@item FOPEN_RB
|
| -Define this if binary files are opened the same way as text files.
|
| -
|
| -@item CC_HAS_LONG_LONG
|
| -@cindex @code{long long} data type
|
| -Define this if the host C compiler supports @code{long long}. This is set
|
| -by the @code{configure} script.
|
| -
|
| -@item PRINTF_HAS_LONG_LONG
|
| -Define this if the host can handle printing of long long integers via
|
| -the printf format conversion specifier @code{ll}. This is set by the
|
| -@code{configure} script.
|
| -
|
| -@item LSEEK_NOT_LINEAR
|
| -Define this if @code{lseek (n)} does not necessarily move to byte number
|
| -@code{n} in the file. This is only used when reading source files. It
|
| -is normally faster to define @code{CRLF_SOURCE_FILES} when possible.
|
| -
|
| -@item lint
|
| -Define this to help placate @code{lint} in some situations.
|
| -
|
| -@item volatile
|
| -Define this to override the defaults of @code{__volatile__} or
|
| -@code{/**/}.
|
| -@end ftable
|
| -
|
| -
|
| -@node Target Architecture Definition
|
| -
|
| -@chapter Target Architecture Definition
|
| -
|
| -@cindex target architecture definition
|
| -@value{GDBN}'s target architecture defines what sort of
|
| -machine-language programs @value{GDBN} can work with, and how it works
|
| -with them.
|
| -
|
| -The target architecture object is implemented as the C structure
|
| -@code{struct gdbarch *}. The structure, and its methods, are generated
|
| -using the Bourne shell script @file{gdbarch.sh}.
|
| -
|
| -@menu
|
| -* OS ABI Variant Handling::
|
| -* Initialize New Architecture::
|
| -* Registers and Memory::
|
| -* Pointers and Addresses::
|
| -* Address Classes::
|
| -* Register Representation::
|
| -* Frame Interpretation::
|
| -* Inferior Call Setup::
|
| -* Adding support for debugging core files::
|
| -* Defining Other Architecture Features::
|
| -* Adding a New Target::
|
| -@end menu
|
| -
|
| -@node OS ABI Variant Handling
|
| -@section Operating System ABI Variant Handling
|
| -@cindex OS ABI variants
|
| -
|
| -@value{GDBN} provides a mechanism for handling variations in OS
|
| -ABIs. An OS ABI variant may have influence over any number of
|
| -variables in the target architecture definition. There are two major
|
| -components in the OS ABI mechanism: sniffers and handlers.
|
| -
|
| -A @dfn{sniffer} examines a file matching a BFD architecture/flavour pair
|
| -(the architecture may be wildcarded) in an attempt to determine the
|
| -OS ABI of that file. Sniffers with a wildcarded architecture are considered
|
| -to be @dfn{generic}, while sniffers for a specific architecture are
|
| -considered to be @dfn{specific}. A match from a specific sniffer
|
| -overrides a match from a generic sniffer. Multiple sniffers for an
|
| -architecture/flavour may exist, in order to differentiate between two
|
| -different operating systems which use the same basic file format. The
|
| -OS ABI framework provides a generic sniffer for ELF-format files which
|
| -examines the @code{EI_OSABI} field of the ELF header, as well as note
|
| -sections known to be used by several operating systems.
|
| -
|
| -@cindex fine-tuning @code{gdbarch} structure
|
| -A @dfn{handler} is used to fine-tune the @code{gdbarch} structure for the
|
| -selected OS ABI. There may be only one handler for a given OS ABI
|
| -for each BFD architecture.
|
| -
|
| -The following OS ABI variants are defined in @file{defs.h}:
|
| -
|
| -@table @code
|
| -
|
| -@findex GDB_OSABI_UNINITIALIZED
|
| -@item GDB_OSABI_UNINITIALIZED
|
| -Used for struct gdbarch_info if ABI is still uninitialized.
|
| -
|
| -@findex GDB_OSABI_UNKNOWN
|
| -@item GDB_OSABI_UNKNOWN
|
| -The ABI of the inferior is unknown. The default @code{gdbarch}
|
| -settings for the architecture will be used.
|
| -
|
| -@findex GDB_OSABI_SVR4
|
| -@item GDB_OSABI_SVR4
|
| -UNIX System V Release 4.
|
| -
|
| -@findex GDB_OSABI_HURD
|
| -@item GDB_OSABI_HURD
|
| -GNU using the Hurd kernel.
|
| -
|
| -@findex GDB_OSABI_SOLARIS
|
| -@item GDB_OSABI_SOLARIS
|
| -Sun Solaris.
|
| -
|
| -@findex GDB_OSABI_OSF1
|
| -@item GDB_OSABI_OSF1
|
| -OSF/1, including Digital UNIX and Compaq Tru64 UNIX.
|
| -
|
| -@findex GDB_OSABI_LINUX
|
| -@item GDB_OSABI_LINUX
|
| -GNU using the Linux kernel.
|
| -
|
| -@findex GDB_OSABI_FREEBSD_AOUT
|
| -@item GDB_OSABI_FREEBSD_AOUT
|
| -FreeBSD using the @code{a.out} executable format.
|
| -
|
| -@findex GDB_OSABI_FREEBSD_ELF
|
| -@item GDB_OSABI_FREEBSD_ELF
|
| -FreeBSD using the ELF executable format.
|
| -
|
| -@findex GDB_OSABI_NETBSD_AOUT
|
| -@item GDB_OSABI_NETBSD_AOUT
|
| -NetBSD using the @code{a.out} executable format.
|
| -
|
| -@findex GDB_OSABI_NETBSD_ELF
|
| -@item GDB_OSABI_NETBSD_ELF
|
| -NetBSD using the ELF executable format.
|
| -
|
| -@findex GDB_OSABI_OPENBSD_ELF
|
| -@item GDB_OSABI_OPENBSD_ELF
|
| -OpenBSD using the ELF executable format.
|
| -
|
| -@findex GDB_OSABI_WINCE
|
| -@item GDB_OSABI_WINCE
|
| -Windows CE.
|
| -
|
| -@findex GDB_OSABI_GO32
|
| -@item GDB_OSABI_GO32
|
| -DJGPP.
|
| -
|
| -@findex GDB_OSABI_IRIX
|
| -@item GDB_OSABI_IRIX
|
| -Irix.
|
| -
|
| -@findex GDB_OSABI_INTERIX
|
| -@item GDB_OSABI_INTERIX
|
| -Interix (Posix layer for MS-Windows systems).
|
| -
|
| -@findex GDB_OSABI_HPUX_ELF
|
| -@item GDB_OSABI_HPUX_ELF
|
| -HP/UX using the ELF executable format.
|
| -
|
| -@findex GDB_OSABI_HPUX_SOM
|
| -@item GDB_OSABI_HPUX_SOM
|
| -HP/UX using the SOM executable format.
|
| -
|
| -@findex GDB_OSABI_QNXNTO
|
| -@item GDB_OSABI_QNXNTO
|
| -QNX Neutrino.
|
| -
|
| -@findex GDB_OSABI_CYGWIN
|
| -@item GDB_OSABI_CYGWIN
|
| -Cygwin.
|
| -
|
| -@findex GDB_OSABI_AIX
|
| -@item GDB_OSABI_AIX
|
| -AIX.
|
| -
|
| -@end table
|
| -
|
| -Here are the functions that make up the OS ABI framework:
|
| -
|
| -@deftypefun {const char *} gdbarch_osabi_name (enum gdb_osabi @var{osabi})
|
| -Return the name of the OS ABI corresponding to @var{osabi}.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void gdbarch_register_osabi (enum bfd_architecture @var{arch}, unsigned long @var{machine}, enum gdb_osabi @var{osabi}, void (*@var{init_osabi})(struct gdbarch_info @var{info}, struct gdbarch *@var{gdbarch}))
|
| -Register the OS ABI handler specified by @var{init_osabi} for the
|
| -architecture, machine type and OS ABI specified by @var{arch},
|
| -@var{machine} and @var{osabi}. In most cases, a value of zero for the
|
| -machine type, which implies the architecture's default machine type,
|
| -will suffice.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void gdbarch_register_osabi_sniffer (enum bfd_architecture @var{arch}, enum bfd_flavour @var{flavour}, enum gdb_osabi (*@var{sniffer})(bfd *@var{abfd}))
|
| -Register the OS ABI file sniffer specified by @var{sniffer} for the
|
| -BFD architecture/flavour pair specified by @var{arch} and @var{flavour}.
|
| -If @var{arch} is @code{bfd_arch_unknown}, the sniffer is considered to
|
| -be generic, and is allowed to examine @var{flavour}-flavoured files for
|
| -any architecture.
|
| -@end deftypefun
|
| -
|
| -@deftypefun {enum gdb_osabi} gdbarch_lookup_osabi (bfd *@var{abfd})
|
| -Examine the file described by @var{abfd} to determine its OS ABI.
|
| -The value @code{GDB_OSABI_UNKNOWN} is returned if the OS ABI cannot
|
| -be determined.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void gdbarch_init_osabi (struct gdbarch info @var{info}, struct gdbarch *@var{gdbarch}, enum gdb_osabi @var{osabi})
|
| -Invoke the OS ABI handler corresponding to @var{osabi} to fine-tune the
|
| -@code{gdbarch} structure specified by @var{gdbarch}. If a handler
|
| -corresponding to @var{osabi} has not been registered for @var{gdbarch}'s
|
| -architecture, a warning will be issued and the debugging session will continue
|
| -with the defaults already established for @var{gdbarch}.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void generic_elf_osabi_sniff_abi_tag_sections (bfd *@var{abfd}, asection *@var{sect}, void *@var{obj})
|
| -Helper routine for ELF file sniffers. Examine the file described by
|
| -@var{abfd} and look at ABI tag note sections to determine the OS ABI
|
| -from the note. This function should be called via
|
| -@code{bfd_map_over_sections}.
|
| -@end deftypefun
|
| -
|
| -@node Initialize New Architecture
|
| -@section Initializing a New Architecture
|
| -
|
| -@menu
|
| -* How an Architecture is Represented::
|
| -* Looking Up an Existing Architecture::
|
| -* Creating a New Architecture::
|
| -@end menu
|
| -
|
| -@node How an Architecture is Represented
|
| -@subsection How an Architecture is Represented
|
| -@cindex architecture representation
|
| -@cindex representation of architecture
|
| -
|
| -Each @code{gdbarch} is associated with a single @sc{bfd} architecture,
|
| -via a @code{bfd_arch_@var{arch}} in the @code{bfd_architecture}
|
| -enumeration. The @code{gdbarch} is registered by a call to
|
| -@code{register_gdbarch_init}, usually from the file's
|
| -@code{_initialize_@var{filename}} routine, which will be automatically
|
| -called during @value{GDBN} startup. The arguments are a @sc{bfd}
|
| -architecture constant and an initialization function.
|
| -
|
| -@findex _initialize_@var{arch}_tdep
|
| -@cindex @file{@var{arch}-tdep.c}
|
| -A @value{GDBN} description for a new architecture, @var{arch} is created by
|
| -defining a global function @code{_initialize_@var{arch}_tdep}, by
|
| -convention in the source file @file{@var{arch}-tdep.c}. For example,
|
| -in the case of the OpenRISC 1000, this function is called
|
| -@code{_initialize_or1k_tdep} and is found in the file
|
| -@file{or1k-tdep.c}.
|
| -
|
| -@cindex @file{configure.tgt}
|
| -@cindex @code{gdbarch}
|
| -@findex gdbarch_register
|
| -The resulting object files containing the implementation of the
|
| -@code{_initialize_@var{arch}_tdep} function are specified in the @value{GDBN}
|
| -@file{configure.tgt} file, which includes a large case statement
|
| -pattern matching against the @code{--target} option of the
|
| -@code{configure} script. The new @code{struct gdbarch} is created
|
| -within the @code{_initialize_@var{arch}_tdep} function by calling
|
| -@code{gdbarch_register}:
|
| -
|
| -@smallexample
|
| -void gdbarch_register (enum bfd_architecture @var{architecture},
|
| - gdbarch_init_ftype *@var{init_func},
|
| - gdbarch_dump_tdep_ftype *@var{tdep_dump_func});
|
| -@end smallexample
|
| -
|
| -The @var{architecture} will identify the unique @sc{bfd} to be
|
| -associated with this @code{gdbarch}. The @var{init_func} funciton is
|
| -called to create and return the new @code{struct gdbarch}. The
|
| -@var{tdep_dump_func} function will dump the target specific details
|
| -associated with this architecture.
|
| -
|
| -For example the function @code{_initialize_or1k_tdep} creates its
|
| -architecture for 32-bit OpenRISC 1000 architectures by calling:
|
| -
|
| -@smallexample
|
| -gdbarch_register (bfd_arch_or32, or1k_gdbarch_init, or1k_dump_tdep);
|
| -@end smallexample
|
| -
|
| -@node Looking Up an Existing Architecture
|
| -@subsection Looking Up an Existing Architecture
|
| -@cindex @code{gdbarch} lookup
|
| -
|
| -The initialization function has this prototype:
|
| -
|
| -@smallexample
|
| -static struct gdbarch *
|
| -@var{arch}_gdbarch_init (struct gdbarch_info @var{info},
|
| - struct gdbarch_list *@var{arches})
|
| -@end smallexample
|
| -
|
| -The @var{info} argument contains parameters used to select the correct
|
| -architecture, and @var{arches} is a list of architectures which
|
| -have already been created with the same @code{bfd_arch_@var{arch}}
|
| -value.
|
| -
|
| -The initialization function should first make sure that @var{info}
|
| -is acceptable, and return @code{NULL} if it is not. Then, it should
|
| -search through @var{arches} for an exact match to @var{info}, and
|
| -return one if found. Lastly, if no exact match was found, it should
|
| -create a new architecture based on @var{info} and return it.
|
| -
|
| -@findex gdbarch_list_lookup_by_info
|
| -@cindex @code{gdbarch_info}
|
| -The lookup is done using @code{gdbarch_list_lookup_by_info}. It is
|
| -passed the list of existing architectures, @var{arches}, and the
|
| -@code{struct gdbarch_info}, @var{info}, and returns the first matching
|
| -architecture it finds, or @code{NULL} if none are found. If an
|
| -architecture is found it can be returned as the result from the
|
| -initialization function, otherwise a new @code{struct gdbach} will need
|
| -to be created.
|
| -
|
| -The struct gdbarch_info has the following components:
|
| -
|
| -@smallexample
|
| -struct gdbarch_info
|
| -@{
|
| - const struct bfd_arch_info *bfd_arch_info;
|
| - int byte_order;
|
| - bfd *abfd;
|
| - struct gdbarch_tdep_info *tdep_info;
|
| - enum gdb_osabi osabi;
|
| - const struct target_desc *target_desc;
|
| -@};
|
| -@end smallexample
|
| -
|
| -@vindex bfd_arch_info
|
| -The @code{bfd_arch_info} member holds the key details about the
|
| -architecture. The @code{byte_order} member is a value in an
|
| -enumeration indicating the endianism. The @code{abfd} member is a
|
| -pointer to the full @sc{bfd}, the @code{tdep_info} member is
|
| -additional custom target specific information, @code{osabi} identifies
|
| -which (if any) of a number of operating specific ABIs are used by this
|
| -architecture and the @code{target_desc} member is a set of name-value
|
| -pairs with information about register usage in this target.
|
| -
|
| -When the @code{struct gdbarch} initialization function is called, not
|
| -all the fields are provided---only those which can be deduced from the
|
| -@sc{bfd}. The @code{struct gdbarch_info}, @var{info} is used as a
|
| -look-up key with the list of existing architectures, @var{arches} to
|
| -see if a suitable architecture already exists. The @var{tdep_info},
|
| -@var{osabi} and @var{target_desc} fields may be added before this
|
| -lookup to refine the search.
|
| -
|
| -Only information in @var{info} should be used to choose the new
|
| -architecture. Historically, @var{info} could be sparse, and
|
| -defaults would be collected from the first element on @var{arches}.
|
| -However, @value{GDBN} now fills in @var{info} more thoroughly,
|
| -so new @code{gdbarch} initialization functions should not take
|
| -defaults from @var{arches}.
|
| -
|
| -@node Creating a New Architecture
|
| -@subsection Creating a New Architecture
|
| -@cindex @code{struct gdbarch} creation
|
| -
|
| -@findex gdbarch_alloc
|
| -@cindex @code{gdbarch_tdep} when allocating new @code{gdbarch}
|
| -If no architecture is found, then a new architecture must be created,
|
| -by calling @code{gdbarch_alloc} using the supplied @code{@w{struct
|
| -gdbarch_info}} and any additional custom target specific
|
| -information in a @code{struct gdbarch_tdep}. The prototype for
|
| -@code{gdbarch_alloc} is:
|
| -
|
| -@smallexample
|
| -struct gdbarch *gdbarch_alloc (const struct gdbarch_info *@var{info},
|
| - struct gdbarch_tdep *@var{tdep});
|
| -@end smallexample
|
| -
|
| -@cindex @code{set_gdbarch} functions
|
| -@cindex @code{gdbarch} accessor functions
|
| -The newly created struct gdbarch must then be populated. Although
|
| -there are default values, in most cases they are not what is
|
| -required.
|
| -
|
| -For each element, @var{X}, there is are a pair of corresponding accessor
|
| -functions, one to set the value of that element,
|
| -@code{set_gdbarch_@var{X}}, the second to either get the value of an
|
| -element (if it is a variable) or to apply the element (if it is a
|
| -function), @code{gdbarch_@var{X}}. Note that both accessor functions
|
| -take a pointer to the @code{@w{struct gdbarch}} as first
|
| -argument. Populating the new @code{gdbarch} should use the
|
| -@code{set_gdbarch} functions.
|
| -
|
| -The following sections identify the main elements that should be set
|
| -in this way. This is not the complete list, but represents the
|
| -functions and elements that must commonly be specified for a new
|
| -architecture. Many of the functions and variables are described in the
|
| -header file @file{gdbarch.h}.
|
| -
|
| -This is the main work in defining a new architecture. Implementing the
|
| -set of functions to populate the @code{struct gdbarch}.
|
| -
|
| -@cindex @code{gdbarch_tdep} definition
|
| -@code{struct gdbarch_tdep} is not defined within @value{GDBN}---it is up
|
| -to the user to define this struct if it is needed to hold custom target
|
| -information that is not covered by the standard @code{@w{struct
|
| -gdbarch}}. For example with the OpenRISC 1000 architecture it is used to
|
| -hold the number of matchpoints available in the target (along with other
|
| -information).
|
| -
|
| -If there is no additional target specific information, it can be set to
|
| -@code{NULL}.
|
| -
|
| -@node Registers and Memory
|
| -@section Registers and Memory
|
| -
|
| -@value{GDBN}'s model of the target machine is rather simple.
|
| -@value{GDBN} assumes the machine includes a bank of registers and a
|
| -block of memory. Each register may have a different size.
|
| -
|
| -@value{GDBN} does not have a magical way to match up with the
|
| -compiler's idea of which registers are which; however, it is critical
|
| -that they do match up accurately. The only way to make this work is
|
| -to get accurate information about the order that the compiler uses,
|
| -and to reflect that in the @code{gdbarch_register_name} and related functions.
|
| -
|
| -@value{GDBN} can handle big-endian, little-endian, and bi-endian architectures.
|
| -
|
| -@node Pointers and Addresses
|
| -@section Pointers Are Not Always Addresses
|
| -@cindex pointer representation
|
| -@cindex address representation
|
| -@cindex word-addressed machines
|
| -@cindex separate data and code address spaces
|
| -@cindex spaces, separate data and code address
|
| -@cindex address spaces, separate data and code
|
| -@cindex code pointers, word-addressed
|
| -@cindex converting between pointers and addresses
|
| -@cindex D10V addresses
|
| -
|
| -On almost all 32-bit architectures, the representation of a pointer is
|
| -indistinguishable from the representation of some fixed-length number
|
| -whose value is the byte address of the object pointed to. On such
|
| -machines, the words ``pointer'' and ``address'' can be used interchangeably.
|
| -However, architectures with smaller word sizes are often cramped for
|
| -address space, so they may choose a pointer representation that breaks this
|
| -identity, and allows a larger code address space.
|
| -
|
| -@c D10V is gone from sources - more current example?
|
| -
|
| -For example, the Renesas D10V is a 16-bit VLIW processor whose
|
| -instructions are 32 bits long@footnote{Some D10V instructions are
|
| -actually pairs of 16-bit sub-instructions. However, since you can't
|
| -jump into the middle of such a pair, code addresses can only refer to
|
| -full 32 bit instructions, which is what matters in this explanation.}.
|
| -If the D10V used ordinary byte addresses to refer to code locations,
|
| -then the processor would only be able to address 64kb of instructions.
|
| -However, since instructions must be aligned on four-byte boundaries, the
|
| -low two bits of any valid instruction's byte address are always
|
| -zero---byte addresses waste two bits. So instead of byte addresses,
|
| -the D10V uses word addresses---byte addresses shifted right two bits---to
|
| -refer to code. Thus, the D10V can use 16-bit words to address 256kb of
|
| -code space.
|
| -
|
| -However, this means that code pointers and data pointers have different
|
| -forms on the D10V. The 16-bit word @code{0xC020} refers to byte address
|
| -@code{0xC020} when used as a data address, but refers to byte address
|
| -@code{0x30080} when used as a code address.
|
| -
|
| -(The D10V also uses separate code and data address spaces, which also
|
| -affects the correspondence between pointers and addresses, but we're
|
| -going to ignore that here; this example is already too long.)
|
| -
|
| -To cope with architectures like this---the D10V is not the only
|
| -one!---@value{GDBN} tries to distinguish between @dfn{addresses}, which are
|
| -byte numbers, and @dfn{pointers}, which are the target's representation
|
| -of an address of a particular type of data. In the example above,
|
| -@code{0xC020} is the pointer, which refers to one of the addresses
|
| -@code{0xC020} or @code{0x30080}, depending on the type imposed upon it.
|
| -@value{GDBN} provides functions for turning a pointer into an address
|
| -and vice versa, in the appropriate way for the current architecture.
|
| -
|
| -Unfortunately, since addresses and pointers are identical on almost all
|
| -processors, this distinction tends to bit-rot pretty quickly. Thus,
|
| -each time you port @value{GDBN} to an architecture which does
|
| -distinguish between pointers and addresses, you'll probably need to
|
| -clean up some architecture-independent code.
|
| -
|
| -Here are functions which convert between pointers and addresses:
|
| -
|
| -@deftypefun CORE_ADDR extract_typed_address (void *@var{buf}, struct type *@var{type})
|
| -Treat the bytes at @var{buf} as a pointer or reference of type
|
| -@var{type}, and return the address it represents, in a manner
|
| -appropriate for the current architecture. This yields an address
|
| -@value{GDBN} can use to read target memory, disassemble, etc. Note that
|
| -@var{buf} refers to a buffer in @value{GDBN}'s memory, not the
|
| -inferior's.
|
| -
|
| -For example, if the current architecture is the Intel x86, this function
|
| -extracts a little-endian integer of the appropriate length from
|
| -@var{buf} and returns it. However, if the current architecture is the
|
| -D10V, this function will return a 16-bit integer extracted from
|
| -@var{buf}, multiplied by four if @var{type} is a pointer to a function.
|
| -
|
| -If @var{type} is not a pointer or reference type, then this function
|
| -will signal an internal error.
|
| -@end deftypefun
|
| -
|
| -@deftypefun CORE_ADDR store_typed_address (void *@var{buf}, struct type *@var{type}, CORE_ADDR @var{addr})
|
| -Store the address @var{addr} in @var{buf}, in the proper format for a
|
| -pointer of type @var{type} in the current architecture. Note that
|
| -@var{buf} refers to a buffer in @value{GDBN}'s memory, not the
|
| -inferior's.
|
| -
|
| -For example, if the current architecture is the Intel x86, this function
|
| -stores @var{addr} unmodified as a little-endian integer of the
|
| -appropriate length in @var{buf}. However, if the current architecture
|
| -is the D10V, this function divides @var{addr} by four if @var{type} is
|
| -a pointer to a function, and then stores it in @var{buf}.
|
| -
|
| -If @var{type} is not a pointer or reference type, then this function
|
| -will signal an internal error.
|
| -@end deftypefun
|
| -
|
| -@deftypefun CORE_ADDR value_as_address (struct value *@var{val})
|
| -Assuming that @var{val} is a pointer, return the address it represents,
|
| -as appropriate for the current architecture.
|
| -
|
| -This function actually works on integral values, as well as pointers.
|
| -For pointers, it performs architecture-specific conversions as
|
| -described above for @code{extract_typed_address}.
|
| -@end deftypefun
|
| -
|
| -@deftypefun CORE_ADDR value_from_pointer (struct type *@var{type}, CORE_ADDR @var{addr})
|
| -Create and return a value representing a pointer of type @var{type} to
|
| -the address @var{addr}, as appropriate for the current architecture.
|
| -This function performs architecture-specific conversions as described
|
| -above for @code{store_typed_address}.
|
| -@end deftypefun
|
| -
|
| -Here are two functions which architectures can define to indicate the
|
| -relationship between pointers and addresses. These have default
|
| -definitions, appropriate for architectures on which all pointers are
|
| -simple unsigned byte addresses.
|
| -
|
| -@deftypefun CORE_ADDR gdbarch_pointer_to_address (struct gdbarch *@var{gdbarch}, struct type *@var{type}, char *@var{buf})
|
| -Assume that @var{buf} holds a pointer of type @var{type}, in the
|
| -appropriate format for the current architecture. Return the byte
|
| -address the pointer refers to.
|
| -
|
| -This function may safely assume that @var{type} is either a pointer or a
|
| -C@t{++} reference type.
|
| -@end deftypefun
|
| -
|
| -@deftypefun void gdbarch_address_to_pointer (struct gdbarch *@var{gdbarch}, struct type *@var{type}, char *@var{buf}, CORE_ADDR @var{addr})
|
| -Store in @var{buf} a pointer of type @var{type} representing the address
|
| -@var{addr}, in the appropriate format for the current architecture.
|
| -
|
| -This function may safely assume that @var{type} is either a pointer or a
|
| -C@t{++} reference type.
|
| -@end deftypefun
|
| -
|
| -@node Address Classes
|
| -@section Address Classes
|
| -@cindex address classes
|
| -@cindex DW_AT_byte_size
|
| -@cindex DW_AT_address_class
|
| -
|
| -Sometimes information about different kinds of addresses is available
|
| -via the debug information. For example, some programming environments
|
| -define addresses of several different sizes. If the debug information
|
| -distinguishes these kinds of address classes through either the size
|
| -info (e.g, @code{DW_AT_byte_size} in @w{DWARF 2}) or through an explicit
|
| -address class attribute (e.g, @code{DW_AT_address_class} in @w{DWARF 2}), the
|
| -following macros should be defined in order to disambiguate these
|
| -types within @value{GDBN} as well as provide the added information to
|
| -a @value{GDBN} user when printing type expressions.
|
| -
|
| -@deftypefun int gdbarch_address_class_type_flags (struct gdbarch *@var{gdbarch}, int @var{byte_size}, int @var{dwarf2_addr_class})
|
| -Returns the type flags needed to construct a pointer type whose size
|
| -is @var{byte_size} and whose address class is @var{dwarf2_addr_class}.
|
| -This function is normally called from within a symbol reader. See
|
| -@file{dwarf2read.c}.
|
| -@end deftypefun
|
| -
|
| -@deftypefun {char *} gdbarch_address_class_type_flags_to_name (struct gdbarch *@var{gdbarch}, int @var{type_flags})
|
| -Given the type flags representing an address class qualifier, return
|
| -its name.
|
| -@end deftypefun
|
| -@deftypefun int gdbarch_address_class_name_to_type_flags (struct gdbarch *@var{gdbarch}, int @var{name}, int *@var{type_flags_ptr})
|
| -Given an address qualifier name, set the @code{int} referenced by @var{type_flags_ptr} to the type flags
|
| -for that address class qualifier.
|
| -@end deftypefun
|
| -
|
| -Since the need for address classes is rather rare, none of
|
| -the address class functions are defined by default. Predicate
|
| -functions are provided to detect when they are defined.
|
| -
|
| -Consider a hypothetical architecture in which addresses are normally
|
| -32-bits wide, but 16-bit addresses are also supported. Furthermore,
|
| -suppose that the @w{DWARF 2} information for this architecture simply
|
| -uses a @code{DW_AT_byte_size} value of 2 to indicate the use of one
|
| -of these "short" pointers. The following functions could be defined
|
| -to implement the address class functions:
|
| -
|
| -@smallexample
|
| -somearch_address_class_type_flags (int byte_size,
|
| - int dwarf2_addr_class)
|
| -@{
|
| - if (byte_size == 2)
|
| - return TYPE_FLAG_ADDRESS_CLASS_1;
|
| - else
|
| - return 0;
|
| -@}
|
| -
|
| -static char *
|
| -somearch_address_class_type_flags_to_name (int type_flags)
|
| -@{
|
| - if (type_flags & TYPE_FLAG_ADDRESS_CLASS_1)
|
| - return "short";
|
| - else
|
| - return NULL;
|
| -@}
|
| -
|
| -int
|
| -somearch_address_class_name_to_type_flags (char *name,
|
| - int *type_flags_ptr)
|
| -@{
|
| - if (strcmp (name, "short") == 0)
|
| - @{
|
| - *type_flags_ptr = TYPE_FLAG_ADDRESS_CLASS_1;
|
| - return 1;
|
| - @}
|
| - else
|
| - return 0;
|
| -@}
|
| -@end smallexample
|
| -
|
| -The qualifier @code{@@short} is used in @value{GDBN}'s type expressions
|
| -to indicate the presence of one of these ``short'' pointers. For
|
| -example if the debug information indicates that @code{short_ptr_var} is
|
| -one of these short pointers, @value{GDBN} might show the following
|
| -behavior:
|
| -
|
| -@smallexample
|
| -(gdb) ptype short_ptr_var
|
| -type = int * @@short
|
| -@end smallexample
|
| -
|
| -
|
| -@node Register Representation
|
| -@section Register Representation
|
| -
|
| -@menu
|
| -* Raw and Cooked Registers::
|
| -* Register Architecture Functions & Variables::
|
| -* Register Information Functions::
|
| -* Register and Memory Data::
|
| -* Register Caching::
|
| -@end menu
|
| -
|
| -@node Raw and Cooked Registers
|
| -@subsection Raw and Cooked Registers
|
| -@cindex raw register representation
|
| -@cindex cooked register representation
|
| -@cindex representations, raw and cooked registers
|
| -
|
| -@value{GDBN} considers registers to be a set with members numbered
|
| -linearly from 0 upwards. The first part of that set corresponds to real
|
| -physical registers, the second part to any @dfn{pseudo-registers}.
|
| -Pseudo-registers have no independent physical existence, but are useful
|
| -representations of information within the architecture. For example the
|
| -OpenRISC 1000 architecture has up to 32 general purpose registers, which
|
| -are typically represented as 32-bit (or 64-bit) integers. However the
|
| -GPRs are also used as operands to the floating point operations, and it
|
| -could be convenient to define a set of pseudo-registers, to show the
|
| -GPRs represented as floating point values.
|
| -
|
| -For any architecture, the implementer will decide on a mapping from
|
| -hardware to @value{GDBN} register numbers. The registers corresponding to real
|
| -hardware are referred to as @dfn{raw} registers, the remaining registers are
|
| -@dfn{pseudo-registers}. The total register set (raw and pseudo) is called
|
| -the @dfn{cooked} register set.
|
| -
|
| -
|
| -@node Register Architecture Functions & Variables
|
| -@subsection Functions and Variables Specifying the Register Architecture
|
| -@cindex @code{gdbarch} register architecture functions
|
| -
|
| -These @code{struct gdbarch} functions and variables specify the number
|
| -and type of registers in the architecture.
|
| -
|
| -@deftypefn {Architecture Function} CORE_ADDR read_pc (struct regcache *@var{regcache})
|
| -@end deftypefn
|
| -@deftypefn {Architecture Function} void write_pc (struct regcache *@var{regcache}, CORE_ADDR @var{val})
|
| -
|
| -Read or write the program counter. The default value of both
|
| -functions is @code{NULL} (no function available). If the program
|
| -counter is just an ordinary register, it can be specified in
|
| -@code{struct gdbarch} instead (see @code{pc_regnum} below) and it will
|
| -be read or written using the standard routines to access registers. This
|
| -function need only be specified if the program counter is not an
|
| -ordinary register.
|
| -
|
| -Any register information can be obtained using the supplied register
|
| -cache, @var{regcache}. @xref{Register Caching, , Register Caching}.
|
| -
|
| -@end deftypefn
|
| -
|
| -@deftypefn {Architecture Function} void pseudo_register_read (struct gdbarch *@var{gdbarch}, struct regcache *@var{regcache}, int @var{regnum}, const gdb_byte *@var{buf})
|
| -@end deftypefn
|
| -@deftypefn {Architecture Function} void pseudo_register_write (struct gdbarch *@var{gdbarch}, struct regcache *@var{regcache}, int @var{regnum}, const gdb_byte *@var{buf})
|
| -
|
| -These functions should be defined if there are any pseudo-registers.
|
| -The default value is @code{NULL}. @var{regnum} is the number of the
|
| -register to read or write (which will be a @dfn{cooked} register
|
| -number) and @var{buf} is the buffer where the value read will be
|
| -placed, or from which the value to be written will be taken. The
|
| -value in the buffer may be converted to or from a signed or unsigned
|
| -integral value using one of the utility functions (@pxref{Register and
|
| -Memory Data, , Using Different Register and Memory Data
|
| -Representations}).
|
| -
|
| -The access should be for the specified architecture,
|
| -@var{gdbarch}. Any register information can be obtained using the
|
| -supplied register cache, @var{regcache}. @xref{Register Caching, ,
|
| -Register Caching}.
|
| -
|
| -@end deftypefn
|
| -
|
| -@deftypevr {Architecture Variable} int sp_regnum
|
| -@vindex sp_regnum
|
| -@cindex stack pointer
|
| -@cindex @kbd{$sp}
|
| -
|
| -This specifies the register holding the stack pointer, which may be a
|
| -raw or pseudo-register. It defaults to -1 (not defined), but it is an
|
| -error for it not to be defined.
|
| -
|
| -The value of the stack pointer register can be accessed withing
|
| -@value{GDBN} as the variable @kbd{$sp}.
|
| -
|
| -@end deftypevr
|
| -
|
| -@deftypevr {Architecture Variable} int pc_regnum
|
| -@vindex pc_regnum
|
| -@cindex program counter
|
| -@cindex @kbd{$pc}
|
| -
|
| -This specifies the register holding the program counter, which may be a
|
| -raw or pseudo-register. It defaults to -1 (not defined). If
|
| -@code{pc_regnum} is not defined, then the functions @code{read_pc} and
|
| -@code{write_pc} (see above) must be defined.
|
| -
|
| -The value of the program counter (whether defined as a register, or
|
| -through @code{read_pc} and @code{write_pc}) can be accessed withing
|
| -@value{GDBN} as the variable @kbd{$pc}.
|
| -
|
| -@end deftypevr
|
| -
|
| -@deftypevr {Architecture Variable} int ps_regnum
|
| -@vindex ps_regnum
|
| -@cindex processor status register
|
| -@cindex status register
|
| -@cindex @kbd{$ps}
|
| -
|
| -This specifies the register holding the processor status (often called
|
| -the status register), which may be a raw or pseudo-register. It
|
| -defaults to -1 (not defined).
|
| -
|
| -If defined, the value of this register can be accessed withing
|
| -@value{GDBN} as the variable @kbd{$ps}.
|
| -
|
| -@end deftypevr
|
| -
|
| -@deftypevr {Architecture Variable} int fp0_regnum
|
| -@vindex fp0_regnum
|
| -@cindex first floating point register
|
| -
|
| -This specifies the first floating point register. It defaults to
|
| -0. @code{fp0_regnum} is not needed unless the target offers support
|
| -for floating point.
|
| -
|
| -@end deftypevr
|
| -
|
| -@node Register Information Functions
|
| -@subsection Functions Giving Register Information
|
| -@cindex @code{gdbarch} register information functions
|
| -
|
| -These functions return information about registers.
|
| -
|
| -@deftypefn {Architecture Function} {const char *} register_name (struct gdbarch *@var{gdbarch}, int @var{regnum})
|
| -
|
| -This function should convert a register number (raw or pseudo) to a
|
| -register name (as a C @code{const char *}). This is used both to
|
| -determine the name of a register for output and to work out the meaning
|
| -of any register names used as input. The function may also return
|
| -@code{NULL}, to indicate that @var{regnum} is not a valid register.
|
| -
|
| -For example with the OpenRISC 1000, @value{GDBN} registers 0-31 are the
|
| -General Purpose Registers, register 32 is the program counter and
|
| -register 33 is the supervision register (i.e.@: the processor status
|
| -register), which map to the strings @code{"gpr00"} through
|
| -@code{"gpr31"}, @code{"pc"} and @code{"sr"} respectively. This means
|
| -that the @value{GDBN} command @kbd{print $gpr5} should print the value of
|
| -the OR1K general purpose register 5@footnote{
|
| -@cindex frame pointer
|
| -@cindex @kbd{$fp}
|
| -Historically, @value{GDBN} always had a concept of a frame pointer
|
| -register, which could be accessed via the @value{GDBN} variable,
|
| -@kbd{$fp}. That concept is now deprecated, recognizing that not all
|
| -architectures have a frame pointer. However if an architecture does
|
| -have a frame pointer register, and defines a register or
|
| -pseudo-register with the name @code{"fp"}, then that register will be
|
| -used as the value of the @kbd{$fp} variable.}.
|
| -
|
| -The default value for this function is @code{NULL}, meaning
|
| -undefined. It should always be defined.
|
| -
|
| -The access should be for the specified architecture, @var{gdbarch}.
|
| -
|
| -@end deftypefn
|
| -
|
| -@deftypefn {Architecture Function} {struct type *} register_type (struct gdbarch *@var{gdbarch}, int @var{regnum})
|
| -
|
| -Given a register number, this function identifies the type of data it
|
| -may be holding, specified as a @code{struct type}. @value{GDBN} allows
|
| -creation of arbitrary types, but a number of built in types are
|
| -provided (@code{builtin_type_void}, @code{builtin_type_int32} etc),
|
| -together with functions to derive types from these.
|
| -
|
| -Typically the program counter will have a type of ``pointer to
|
| -function'' (it points to code), the frame pointer and stack pointer
|
| -will have types of ``pointer to void'' (they point to data on the stack)
|
| -and all other integer registers will have a type of 32-bit integer or
|
| -64-bit integer.
|
| -
|
| -This information guides the formatting when displaying register
|
| -information. The default value is @code{NULL} meaning no information is
|
| -available to guide formatting when displaying registers.
|
| -
|
| -@end deftypefn
|
| -
|
| -@deftypefn {Architecture Function} void print_registers_info (struct gdbarch *@var{gdbarch}, struct ui_file *@var{file}, struct frame_info *@var{frame}, int @var{regnum}, int @var{all})
|
| -
|
| -Define this function to print out one or all of the registers for the
|
| -@value{GDBN} @kbd{info registers} command. The default value is the
|
| -function @code{default_print_registers_info}, which uses the register
|
| -type information (see @code{register_type} above) to determine how each
|
| -register should be printed. Define a custom version of this function
|
| -for fuller control over how the registers are displayed.
|
| -
|
| -The access should be for the specified architecture, @var{gdbarch},
|
| -with output to the file specified by the User Interface
|
| -Independent Output file handle, @var{file} (@pxref{UI-Independent
|
| -Output, , UI-Independent Output---the @code{ui_out}
|
| -Functions}).
|
| -
|
| -The registers should show their values in the frame specified by
|
| -@var{frame}. If @var{regnum} is -1 and @var{all} is zero, then all
|
| -the ``significant'' registers should be shown (the implementer should
|
| -decide which registers are ``significant''). Otherwise only the value of
|
| -the register specified by @var{regnum} should be output. If
|
| -@var{regnum} is -1 and @var{all} is non-zero (true), then the value of
|
| -all registers should be shown.
|
| -
|
| -By default @code{default_print_registers_info} prints one register per
|
| -line, and if @var{all} is zero omits floating-point registers.
|
| -
|
| -@end deftypefn
|
| -
|
| -@deftypefn {Architecture Function} void print_float_info (struct gdbarch *@var{gdbarch}, struct ui_file *@var{file}, struct frame_info *@var{frame}, const char *@var{args})
|
| -
|
| -Define this function to provide output about the floating point unit and
|
| -registers for the @value{GDBN} @kbd{info float} command respectively.
|
| -The default value is @code{NULL} (not defined), meaning no information
|
| -will be provided.
|
| -
|
| -The @var{gdbarch} and @var{file} and @var{frame} arguments have the same
|
| -meaning as in the @code{print_registers_info} function above. The string
|
| -@var{args} contains any supplementary arguments to the @kbd{info float}
|
| -command.
|
| -
|
| -Define this function if the target supports floating point operations.
|
| -
|
| -@end deftypefn
|
| -
|
| -@deftypefn {Architecture Function} void print_vector_info (struct gdbarch *@var{gdbarch}, struct ui_file *@var{file}, struct frame_info *@var{frame}, const char *@var{args})
|
| -
|
| -Define this function to provide output about the vector unit and
|
| -registers for the @value{GDBN} @kbd{info vector} command respectively.
|
| -The default value is @code{NULL} (not defined), meaning no information
|
| -will be provided.
|
| -
|
| -The @var{gdbarch}, @var{file} and @var{frame} arguments have the
|
| -same meaning as in the @code{print_registers_info} function above. The
|
| -string @var{args} contains any supplementary arguments to the @kbd{info
|
| -vector} command.
|
| -
|
| -Define this function if the target supports vector operations.
|
| -
|
| -@end deftypefn
|
| -
|
| -@deftypefn {Architecture Function} int register_reggroup_p (struct gdbarch *@var{gdbarch}, int @var{regnum}, struct reggroup *@var{group})
|
| -
|
| -@value{GDBN} groups registers into different categories (general,
|
| -vector, floating point etc). This function, given a register,
|
| -@var{regnum}, and group, @var{group}, returns 1 (true) if the register
|
| -is in the group and 0 (false) otherwise.
|
| -
|
| -The information should be for the specified architecture,
|
| -@var{gdbarch}
|
| -
|
| -The default value is the function @code{default_register_reggroup_p}
|
| -which will do a reasonable job based on the type of the register (see
|
| -the function @code{register_type} above), with groups for general
|
| -purpose registers, floating point registers, vector registers and raw
|
| -(i.e not pseudo) registers.
|
| -
|
| -@end deftypefn
|
| -
|
| -@node Register and Memory Data
|
| -@subsection Using Different Register and Memory Data Representations
|
| -@cindex register representation
|
| -@cindex memory representation
|
| -@cindex representations, register and memory
|
| -@cindex register data formats, converting
|
| -@cindex @code{struct value}, converting register contents to
|
| -
|
| -Some architectures have different representations of data objects,
|
| -depending whether the object is held in a register or memory. For
|
| -example:
|
| -
|
| -@itemize @bullet
|
| -
|
| -@item
|
| -The Alpha architecture can represent 32 bit integer values in
|
| -floating-point registers.
|
| -
|
| -@item
|
| -The x86 architecture supports 80-bit floating-point registers. The
|
| -@code{long double} data type occupies 96 bits in memory but only 80
|
| -bits when stored in a register.
|
| -
|
| -@end itemize
|
| -
|
| -In general, the register representation of a data type is determined by
|
| -the architecture, or @value{GDBN}'s interface to the architecture, while
|
| -the memory representation is determined by the Application Binary
|
| -Interface.
|
| -
|
| -For almost all data types on almost all architectures, the two
|
| -representations are identical, and no special handling is needed.
|
| -However, they do occasionally differ. An architecture may define the
|
| -following @code{struct gdbarch} functions to request conversions
|
| -between the register and memory representations of a data type:
|
| -
|
| -@deftypefn {Architecture Function} int gdbarch_convert_register_p (struct gdbarch *@var{gdbarch}, int @var{reg})
|
| -
|
| -Return non-zero (true) if the representation of a data value stored in
|
| -this register may be different to the representation of that same data
|
| -value when stored in memory. The default value is @code{NULL}
|
| -(undefined).
|
| -
|
| -If this function is defined and returns non-zero, the @code{struct
|
| -gdbarch} functions @code{gdbarch_register_to_value} and
|
| -@code{gdbarch_value_to_register} (see below) should be used to perform
|
| -any necessary conversion.
|
| -
|
| -If defined, this function should return zero for the register's native
|
| -type, when no conversion is necessary.
|
| -@end deftypefn
|
| -
|
| -@deftypefn {Architecture Function} void gdbarch_register_to_value (struct gdbarch *@var{gdbarch}, int @var{reg}, struct type *@var{type}, char *@var{from}, char *@var{to})
|
| -
|
| -Convert the value of register number @var{reg} to a data object of
|
| -type @var{type}. The buffer at @var{from} holds the register's value
|
| -in raw format; the converted value should be placed in the buffer at
|
| -@var{to}.
|
| -
|
| -@quotation
|
| -@emph{Note:} @code{gdbarch_register_to_value} and
|
| -@code{gdbarch_value_to_register} take their @var{reg} and @var{type}
|
| -arguments in different orders.
|
| -@end quotation
|
| -
|
| -@code{gdbarch_register_to_value} should only be used with registers
|
| -for which the @code{gdbarch_convert_register_p} function returns a
|
| -non-zero value.
|
| -
|
| -@end deftypefn
|
| -
|
| -@deftypefn {Architecture Function} void gdbarch_value_to_register (struct gdbarch *@var{gdbarch}, struct type *@var{type}, int @var{reg}, char *@var{from}, char *@var{to})
|
| -
|
| -Convert a data value of type @var{type} to register number @var{reg}'
|
| -raw format.
|
| -
|
| -@quotation
|
| -@emph{Note:} @code{gdbarch_register_to_value} and
|
| -@code{gdbarch_value_to_register} take their @var{reg} and @var{type}
|
| -arguments in different orders.
|
| -@end quotation
|
| -
|
| -@code{gdbarch_value_to_register} should only be used with registers
|
| -for which the @code{gdbarch_convert_register_p} function returns a
|
| -non-zero value.
|
| -
|
| -@end deftypefn
|
| -
|
| -@node Register Caching
|
| -@subsection Register Caching
|
| -@cindex register caching
|
| -
|
| -Caching of registers is used, so that the target does not need to be
|
| -accessed and reanalyzed multiple times for each register in
|
| -circumstances where the register value cannot have changed.
|
| -
|
| -@cindex @code{struct regcache}
|
| -@value{GDBN} provides @code{struct regcache}, associated with a
|
| -particular @code{struct gdbarch} to hold the cached values of the raw
|
| -registers. A set of functions is provided to access both the raw
|
| -registers (with @code{raw} in their name) and the full set of cooked
|
| -registers (with @code{cooked} in their name). Functions are provided
|
| -to ensure the register cache is kept synchronized with the values of
|
| -the actual registers in the target.
|
| -
|
| -Accessing registers through the @code{struct regcache} routines will
|
| -ensure that the appropriate @code{struct gdbarch} functions are called
|
| -when necessary to access the underlying target architecture. In general
|
| -users should use the @dfn{cooked} functions, since these will map to the
|
| -@dfn{raw} functions automatically as appropriate.
|
| -
|
| -@findex regcache_cooked_read
|
| -@findex regcache_cooked_write
|
| -@cindex @code{gdb_byte}
|
| -@findex regcache_cooked_read_signed
|
| -@findex regcache_cooked_read_unsigned
|
| -@findex regcache_cooked_write_signed
|
| -@findex regcache_cooked_write_unsigned
|
| -The two key functions are @code{regcache_cooked_read} and
|
| -@code{regcache_cooked_write} which read or write a register from or to
|
| -a byte buffer (type @code{gdb_byte *}). For convenience the wrapper
|
| -functions @code{regcache_cooked_read_signed},
|
| -@code{regcache_cooked_read_unsigned},
|
| -@code{regcache_cooked_write_signed} and
|
| -@code{regcache_cooked_write_unsigned} are provided, which read or
|
| -write the value using the buffer and convert to or from an integral
|
| -value as appropriate.
|
| -
|
| -@node Frame Interpretation
|
| -@section Frame Interpretation
|
| -
|
| -@menu
|
| -* All About Stack Frames::
|
| -* Frame Handling Terminology::
|
| -* Prologue Caches::
|
| -* Functions and Variable to Analyze Frames::
|
| -* Functions to Access Frame Data::
|
| -* Analyzing Stacks---Frame Sniffers::
|
| -@end menu
|
| -
|
| -@node All About Stack Frames
|
| -@subsection All About Stack Frames
|
| -
|
| -@value{GDBN} needs to understand the stack on which local (automatic)
|
| -variables are stored. The area of the stack containing all the local
|
| -variables for a function invocation is known as the @dfn{stack frame}
|
| -for that function (or colloquially just as the @dfn{frame}). In turn the
|
| -function that called the function will have its stack frame, and so on
|
| -back through the chain of functions that have been called.
|
| -
|
| -Almost all architectures have one register dedicated to point to the
|
| -end of the stack (the @dfn{stack pointer}). Many have a second register
|
| -which points to the start of the currently active stack frame (the
|
| -@dfn{frame pointer}). The specific arrangements for an architecture are
|
| -a key part of the ABI.
|
| -
|
| -A diagram helps to explain this. Here is a simple program to compute
|
| -factorials:
|
| -
|
| -@smallexample
|
| -#include <stdio.h>
|
| -int fact (int n)
|
| -@{
|
| - if (0 == n)
|
| - @{
|
| - return 1;
|
| - @}
|
| - else
|
| - @{
|
| - return n * fact (n - 1);
|
| - @}
|
| -@}
|
| -
|
| -main ()
|
| -@{
|
| - int i;
|
| -
|
| - for (i = 0; i < 10; i++)
|
| - @{
|
| - int f = fact (i);
|
| - printf ("%d! = %d\n", i, f);
|
| - @}
|
| -@}
|
| -@end smallexample
|
| -
|
| -Consider the state of the stack when the code reaches line 6 after the
|
| -main program has called @code{fact@w{ }(3)}. The chain of function
|
| -calls will be @code{main ()}, @code{fact@w{ }(3)}, @code{fact@w{
|
| -}(2)}, @code{@w{fact (1)}} and @code{fact@w{ }(0)}.
|
| -
|
| -In this illustration the stack is falling (as used for example by the
|
| -OpenRISC 1000 ABI). The stack pointer (SP) is at the end of the stack
|
| -(lowest address) and the frame pointer (FP) is at the highest address
|
| -in the current stack frame. The following diagram shows how the stack
|
| -looks.
|
| -
|
| -@center @image{stack_frame,14cm}
|
| -
|
| -In each stack frame, offset 0 from the stack pointer is the frame
|
| -pointer of the previous frame and offset 4 (this is illustrating a
|
| -32-bit architecture) from the stack pointer is the return address.
|
| -Local variables are indexed from the frame pointer, with negative
|
| -indexes. In the function @code{fact}, offset -4 from the frame
|
| -pointer is the argument @var{n}. In the @code{main} function, offset
|
| --4 from the frame pointer is the local variable @var{i} and offset -8
|
| -from the frame pointer is the local variable @var{f}@footnote{This is
|
| -a simplified example for illustrative purposes only. Good optimizing
|
| -compilers would not put anything on the stack for such simple
|
| -functions. Indeed they might eliminate the recursion and use of the
|
| -stack entirely!}.
|
| -
|
| -It is very easy to get confused when examining stacks. @value{GDBN}
|
| -has terminology it uses rigorously throughout. The stack frame of the
|
| -function currently executing, or where execution stopped is numbered
|
| -zero. In this example frame #0 is the stack frame of the call to
|
| -@code{fact@w{ }(0)}. The stack frame of its calling function
|
| -(@code{fact@w{ }(1)} in this case) is numbered #1 and so on back
|
| -through the chain of calls.
|
| -
|
| -The main @value{GDBN} data structure describing frames is
|
| - @code{@w{struct frame_info}}. It is not used directly, but only via
|
| -its accessor functions. @code{frame_info} includes information about
|
| -the registers in the frame and a pointer to the code of the function
|
| -with which the frame is associated. The entire stack is represented as
|
| -a linked list of @code{frame_info} structs.
|
| -
|
| -@node Frame Handling Terminology
|
| -@subsection Frame Handling Terminology
|
| -
|
| -It is easy to get confused when referencing stack frames. @value{GDBN}
|
| -uses some precise terminology.
|
| -
|
| -@itemize @bullet
|
| -
|
| -@item
|
| -@cindex THIS frame
|
| -@cindex stack frame, definition of THIS frame
|
| -@cindex frame, definition of THIS frame
|
| -@dfn{THIS} frame is the frame currently under consideration.
|
| -
|
| -@item
|
| -@cindex NEXT frame
|
| -@cindex stack frame, definition of NEXT frame
|
| -@cindex frame, definition of NEXT frame
|
| -The @dfn{NEXT} frame, also sometimes called the inner or newer frame is the
|
| -frame of the function called by the function of THIS frame.
|
| -
|
| -@item
|
| -@cindex PREVIOUS frame
|
| -@cindex stack frame, definition of PREVIOUS frame
|
| -@cindex frame, definition of PREVIOUS frame
|
| -The @dfn{PREVIOUS} frame, also sometimes called the outer or older frame is
|
| -the frame of the function which called the function of THIS frame.
|
| -
|
| -@end itemize
|
| -
|
| -So in the example in the previous section (@pxref{All About Stack
|
| -Frames, , All About Stack Frames}), if THIS frame is #3 (the call to
|
| -@code{fact@w{ }(3)}), the NEXT frame is frame #2 (the call to
|
| -@code{fact@w{ }(2)}) and the PREVIOUS frame is frame #4 (the call to
|
| -@code{main@w{ }()}).
|
| -
|
| -@cindex innermost frame
|
| -@cindex stack frame, definition of innermost frame
|
| -@cindex frame, definition of innermost frame
|
| -The @dfn{innermost} frame is the frame of the current executing
|
| -function, or where the program stopped, in this example, in the middle
|
| -of the call to @code{@w{fact (0))}}. It is always numbered frame #0.
|
| -
|
| -@cindex base of a frame
|
| -@cindex stack frame, definition of base of a frame
|
| -@cindex frame, definition of base of a frame
|
| -The @dfn{base} of a frame is the address immediately before the start
|
| -of the NEXT frame. For a stack which grows down in memory (a
|
| -@dfn{falling} stack) this will be the lowest address and for a stack
|
| -which grows up in memory (a @dfn{rising} stack) this will be the
|
| -highest address in the frame.
|
| -
|
| -@value{GDBN} functions to analyze the stack are typically given a
|
| -pointer to the NEXT frame to determine information about THIS
|
| -frame. Information about THIS frame includes data on where the
|
| -registers of the PREVIOUS frame are stored in this stack frame. In
|
| -this example the frame pointer of the PREVIOUS frame is stored at
|
| -offset 0 from the stack pointer of THIS frame.
|
| -
|
| -@cindex unwinding
|
| -@cindex stack frame, definition of unwinding
|
| -@cindex frame, definition of unwinding
|
| -The process whereby a function is given a pointer to the NEXT
|
| -frame to work out information about THIS frame is referred to as
|
| -@dfn{unwinding}. The @value{GDBN} functions involved in this typically
|
| -include unwind in their name.
|
| -
|
| -@cindex sniffing
|
| -@cindex stack frame, definition of sniffing
|
| -@cindex frame, definition of sniffing
|
| -The process of analyzing a target to determine the information that
|
| -should go in struct frame_info is called @dfn{sniffing}. The functions
|
| -that carry this out are called sniffers and typically include sniffer
|
| -in their name. More than one sniffer may be required to extract all
|
| -the information for a particular frame.
|
| -
|
| -@cindex sentinel frame
|
| -@cindex stack frame, definition of sentinel frame
|
| -@cindex frame, definition of sentinel frame
|
| -Because so many functions work using the NEXT frame, there is an issue
|
| -about addressing the innermost frame---it has no NEXT frame. To solve
|
| -this @value{GDBN} creates a dummy frame #-1, known as the
|
| -@dfn{sentinel} frame.
|
| -
|
| -@node Prologue Caches
|
| -@subsection Prologue Caches
|
| -
|
| -@cindex function prologue
|
| -@cindex prologue of a function
|
| -All the frame sniffing functions typically examine the code at the
|
| -start of the corresponding function, to determine the state of
|
| -registers. The ABI will save old values and set new values of key
|
| -registers at the start of each function in what is known as the
|
| -function @dfn{prologue}.
|
| -
|
| -@cindex prologue cache
|
| -For any particular stack frame this data does not change, so all the
|
| -standard unwinding functions, in addition to receiving a pointer to
|
| -the NEXT frame as their first argument, receive a pointer to a
|
| -@dfn{prologue cache} as their second argument. This can be used to store
|
| -values associated with a particular frame, for reuse on subsequent
|
| -calls involving the same frame.
|
| -
|
| -It is up to the user to define the structure used (it is a
|
| -@code{void@w{ }*} pointer) and arrange allocation and deallocation of
|
| -storage. However for general use, @value{GDBN} provides
|
| -@code{@w{struct trad_frame_cache}}, with a set of accessor
|
| -routines. This structure holds the stack and code address of
|
| -THIS frame, the base address of the frame, a pointer to the
|
| -struct @code{frame_info} for the NEXT frame and details of
|
| -where the registers of the PREVIOUS frame may be found in THIS
|
| -frame.
|
| -
|
| -Typically the first time any sniffer function is called with NEXT
|
| -frame, the prologue sniffer for THIS frame will be @code{NULL}. The
|
| -sniffer will analyze the frame, allocate a prologue cache structure
|
| -and populate it. Subsequent calls using the same NEXT frame will
|
| -pass in this prologue cache, so the data can be returned with no
|
| -additional analysis.
|
| -
|
| -@node Functions and Variable to Analyze Frames
|
| -@subsection Functions and Variable to Analyze Frames
|
| -
|
| -These struct @code{gdbarch} functions and variable should be defined
|
| -to provide analysis of the stack frame and allow it to be adjusted as
|
| -required.
|
| -
|
| -@deftypefn {Architecture Function} CORE_ADDR skip_prologue (struct gdbarch *@var{gdbarch}, CORE_ADDR @var{pc})
|
| -
|
| -The prologue of a function is the code at the beginning of the
|
| -function which sets up the stack frame, saves the return address
|
| -etc. The code representing the behavior of the function starts after
|
| -the prologue.
|
| -
|
| -This function skips past the prologue of a function if the program
|
| -counter, @var{pc}, is within the prologue of a function. The result is
|
| -the program counter immediately after the prologue. With modern
|
| -optimizing compilers, this may be a far from trivial exercise. However
|
| -the required information may be within the binary as DWARF2 debugging
|
| -information, making the job much easier.
|
| -
|
| -The default value is @code{NULL} (not defined). This function should always
|
| -be provided, but can take advantage of DWARF2 debugging information,
|
| -if that is available.
|
| -
|
| -@end deftypefn
|
| -
|
| -@deftypefn {Architecture Function} int inner_than (CORE_ADDR @var{lhs}, CORE_ADDR @var{rhs})
|
| -@findex core_addr_lessthan
|
| -@findex core_addr_greaterthan
|
| -
|
| -Given two frame or stack pointers, return non-zero (true) if the first
|
| -represents the @dfn{inner} stack frame and 0 (false) otherwise. This
|
| -is used to determine whether the target has a stack which grows up in
|
| -memory (rising stack) or grows down in memory (falling stack).
|
| -@xref{All About Stack Frames, , All About Stack Frames}, for an
|
| -explanation of @dfn{inner} frames.
|
| -
|
| -The default value of this function is @code{NULL} and it should always
|
| -be defined. However for almost all architectures one of the built-in
|
| -functions can be used: @code{core_addr_lessthan} (for stacks growing
|
| -down in memory) or @code{core_addr_greaterthan} (for stacks growing up
|
| -in memory).
|
| -
|
| -@end deftypefn
|
| -
|
| -@anchor{frame_align}
|
| -@deftypefn {Architecture Function} CORE_ADDR frame_align (struct gdbarch *@var{gdbarch}, CORE_ADDR @var{address})
|
| -@findex align_down
|
| -@findex align_up
|
| -
|
| -The architecture may have constraints on how its frames are
|
| -aligned. For example the OpenRISC 1000 ABI requires stack frames to be
|
| -double-word aligned, but 32-bit versions of the architecture allocate
|
| -single-word values to the stack. Thus extra padding may be needed at
|
| -the end of a stack frame.
|
| -
|
| -Given a proposed address for the stack pointer, this function
|
| -returns a suitably aligned address (by expanding the stack frame).
|
| -
|
| -The default value is @code{NULL} (undefined). This function should be defined
|
| -for any architecture where it is possible the stack could become
|
| -misaligned. The utility functions @code{align_down} (for falling
|
| -stacks) and @code{align_up} (for rising stacks) will facilitate the
|
| -implementation of this function.
|
| -
|
| -@end deftypefn
|
| -
|
| -@deftypevr {Architecture Variable} int frame_red_zone_size
|
| -
|
| -Some ABIs reserve space beyond the end of the stack for use by leaf
|
| -functions without prologue or epilogue or by exception handlers (for
|
| -example the OpenRISC 1000).
|
| -
|
| -This is known as a @dfn{red zone} (AMD terminology). The @sc{amd64}
|
| -(nee x86-64) ABI documentation refers to the @dfn{red zone} when
|
| -describing this scratch area.
|
| -
|
| -The default value is 0. Set this field if the architecture has such a
|
| -red zone. The value must be aligned as required by the ABI (see
|
| -@code{frame_align} above for an explanation of stack frame alignment).
|
| -
|
| -@end deftypevr
|
| -
|
| -@node Functions to Access Frame Data
|
| -@subsection Functions to Access Frame Data
|
| -
|
| -These functions provide access to key registers and arguments in the
|
| -stack frame.
|
| -
|
| -@deftypefn {Architecture Function} CORE_ADDR unwind_pc (struct gdbarch *@var{gdbarch}, struct frame_info *@var{next_frame})
|
| -
|
| -This function is given a pointer to the NEXT stack frame (@pxref{All
|
| -About Stack Frames, , All About Stack Frames}, for how frames are
|
| -represented) and returns the value of the program counter in the
|
| -PREVIOUS frame (i.e.@: the frame of the function that called THIS
|
| -one). This is commonly referred to as the @dfn{return address}.
|
| -
|
| -The implementation, which must be frame agnostic (work with any frame),
|
| -is typically no more than:
|
| -
|
| -@smallexample
|
| -ULONGEST pc;
|
| -pc = frame_unwind_register_unsigned (next_frame, @var{ARCH}_PC_REGNUM);
|
| -return gdbarch_addr_bits_remove (gdbarch, pc);
|
| -@end smallexample
|
| -
|
| -@end deftypefn
|
| -
|
| -@deftypefn {Architecture Function} CORE_ADDR unwind_sp (struct gdbarch *@var{gdbarch}, struct frame_info *@var{next_frame})
|
| -
|
| -This function is given a pointer to the NEXT stack frame
|
| -(@pxref{All About Stack Frames, , All About Stack Frames} for how
|
| -frames are represented) and returns the value of the stack pointer in
|
| -the PREVIOUS frame (i.e.@: the frame of the function that called
|
| -THIS one).
|
| -
|
| -The implementation, which must be frame agnostic (work with any frame),
|
| -is typically no more than:
|
| -
|
| -@smallexample
|
| -ULONGEST sp;
|
| -sp = frame_unwind_register_unsigned (next_frame, @var{ARCH}_SP_REGNUM);
|
| -return gdbarch_addr_bits_remove (gdbarch, sp);
|
| -@end smallexample
|
| -
|
| -@end deftypefn
|
| -
|
| -@deftypefn {Architecture Function} int frame_num_args (struct gdbarch *@var{gdbarch}, struct frame_info *@var{this_frame})
|
| -
|
| -This function is given a pointer to THIS stack frame (@pxref{All
|
| -About Stack Frames, , All About Stack Frames} for how frames are
|
| -represented), and returns the number of arguments that are being
|
| -passed, or -1 if not known.
|
| -
|
| -The default value is @code{NULL} (undefined), in which case the number of
|
| -arguments passed on any stack frame is always unknown. For many
|
| -architectures this will be a suitable default.
|
| -
|
| -@end deftypefn
|
| -
|
| -@node Analyzing Stacks---Frame Sniffers
|
| -@subsection Analyzing Stacks---Frame Sniffers
|
| -
|
| -When a program stops, @value{GDBN} needs to construct the chain of
|
| -struct @code{frame_info} representing the state of the stack using
|
| -appropriate @dfn{sniffers}.
|
| -
|
| -Each architecture requires appropriate sniffers, but they do not form
|
| -entries in @code{@w{struct gdbarch}}, since more than one sniffer may
|
| -be required and a sniffer may be suitable for more than one
|
| -@code{@w{struct gdbarch}}. Instead sniffers are associated with
|
| -architectures using the following functions.
|
| -
|
| -@itemize @bullet
|
| -
|
| -@item
|
| -@findex frame_unwind_append_sniffer
|
| -@code{frame_unwind_append_sniffer} is used to add a new sniffer to
|
| -analyze THIS frame when given a pointer to the NEXT frame.
|
| -
|
| -@item
|
| -@findex frame_base_append_sniffer
|
| -@code{frame_base_append_sniffer} is used to add a new sniffer
|
| -which can determine information about the base of a stack frame.
|
| -
|
| -@item
|
| -@findex frame_base_set_default
|
| -@code{frame_base_set_default} is used to specify the default base
|
| -sniffer.
|
| -
|
| -@end itemize
|
| -
|
| -These functions all take a reference to @code{@w{struct gdbarch}}, so
|
| -they are associated with a specific architecture. They are usually
|
| -called in the @code{gdbarch} initialization function, after the
|
| -@code{gdbarch} struct has been set up. Unless a default has been set, the
|
| -most recently appended sniffer will be tried first.
|
| -
|
| -The main frame unwinding sniffer (as set by
|
| -@code{frame_unwind_append_sniffer)} returns a structure specifying
|
| -a set of sniffing functions:
|
| -
|
| -@cindex @code{frame_unwind}
|
| -@smallexample
|
| -struct frame_unwind
|
| -@{
|
| - enum frame_type type;
|
| - frame_this_id_ftype *this_id;
|
| - frame_prev_register_ftype *prev_register;
|
| - const struct frame_data *unwind_data;
|
| - frame_sniffer_ftype *sniffer;
|
| - frame_prev_pc_ftype *prev_pc;
|
| - frame_dealloc_cache_ftype *dealloc_cache;
|
| -@};
|
| -@end smallexample
|
| -
|
| -The @code{type} field indicates the type of frame this sniffer can
|
| -handle: normal, dummy (@pxref{Functions Creating Dummy Frames, ,
|
| -Functions Creating Dummy Frames}), signal handler or sentinel. Signal
|
| -handlers sometimes have their own simplified stack structure for
|
| -efficiency, so may need their own handlers.
|
| -
|
| -The @code{unwind_data} field holds additional information which may be
|
| -relevant to particular types of frame. For example it may hold
|
| -additional information for signal handler frames.
|
| -
|
| -The remaining fields define functions that yield different types of
|
| -information when given a pointer to the NEXT stack frame. Not all
|
| -functions need be provided. If an entry is @code{NULL}, the next sniffer will
|
| -be tried instead.
|
| -
|
| -@itemize @bullet
|
| -
|
| -@item
|
| -@code{this_id} determines the stack pointer and function (code
|
| -entry point) for THIS stack frame.
|
| -
|
| -@item
|
| -@code{prev_register} determines where the values of registers for
|
| -the PREVIOUS stack frame are stored in THIS stack frame.
|
| -
|
| -@item
|
| -@code{sniffer} takes a look at THIS frame's registers to
|
| -determine if this is the appropriate unwinder.
|
| -
|
| -@item
|
| -@code{prev_pc} determines the program counter for THIS
|
| -frame. Only needed if the program counter is not an ordinary register
|
| -(@pxref{Register Architecture Functions & Variables,
|
| -, Functions and Variables Specifying the Register Architecture}).
|
| -
|
| -@item
|
| -@code{dealloc_cache} frees any additional memory associated with
|
| -the prologue cache for this frame (@pxref{Prologue Caches, , Prologue
|
| -Caches}).
|
| -
|
| -@end itemize
|
| -
|
| -In general it is only the @code{this_id} and @code{prev_register}
|
| -fields that need be defined for custom sniffers.
|
| -
|
| -The frame base sniffer is much simpler. It is a @code{@w{struct
|
| -frame_base}}, which refers to the corresponding @code{frame_unwind}
|
| -struct and whose fields refer to functions yielding various addresses
|
| -within the frame.
|
| -
|
| -@cindex @code{frame_base}
|
| -@smallexample
|
| -struct frame_base
|
| -@{
|
| - const struct frame_unwind *unwind;
|
| - frame_this_base_ftype *this_base;
|
| - frame_this_locals_ftype *this_locals;
|
| - frame_this_args_ftype *this_args;
|
| -@};
|
| -@end smallexample
|
| -
|
| -All the functions referred to take a pointer to the NEXT frame as
|
| -argument. The function referred to by @code{this_base} returns the
|
| -base address of THIS frame, the function referred to by
|
| -@code{this_locals} returns the base address of local variables in THIS
|
| -frame and the function referred to by @code{this_args} returns the
|
| -base address of the function arguments in this frame.
|
| -
|
| -As described above, the base address of a frame is the address
|
| -immediately before the start of the NEXT frame. For a falling
|
| -stack, this is the lowest address in the frame and for a rising stack
|
| -it is the highest address in the frame. For most architectures the
|
| -same address is also the base address for local variables and
|
| -arguments, in which case the same function can be used for all three
|
| -entries@footnote{It is worth noting that if it cannot be determined in any
|
| -other way (for example by there being a register with the name
|
| -@code{"fp"}), then the result of the @code{this_base} function will be
|
| -used as the value of the frame pointer variable @kbd{$fp} in
|
| -@value{GDBN}. This is very often not correct (for example with the
|
| -OpenRISC 1000, this value is the stack pointer, @kbd{$sp}). In this
|
| -case a register (raw or pseudo) with the name @code{"fp"} should be
|
| -defined. It will be used in preference as the value of @kbd{$fp}.}.
|
| -
|
| -@node Inferior Call Setup
|
| -@section Inferior Call Setup
|
| -@cindex calls to the inferior
|
| -
|
| -@menu
|
| -* About Dummy Frames::
|
| -* Functions Creating Dummy Frames::
|
| -@end menu
|
| -
|
| -@node About Dummy Frames
|
| -@subsection About Dummy Frames
|
| -@cindex dummy frames
|
| -
|
| -@value{GDBN} can call functions in the target code (for example by
|
| -using the @kbd{call} or @kbd{print} commands). These functions may be
|
| -breakpointed, and it is essential that if a function does hit a
|
| -breakpoint, commands like @kbd{backtrace} work correctly.
|
| -
|
| -This is achieved by making the stack look as though the function had
|
| -been called from the point where @value{GDBN} had previously stopped.
|
| -This requires that @value{GDBN} can set up stack frames appropriate for
|
| -such function calls.
|
| -
|
| -@node Functions Creating Dummy Frames
|
| -@subsection Functions Creating Dummy Frames
|
| -
|
| -The following functions provide the functionality to set up such
|
| -@dfn{dummy} stack frames.
|
| -
|
| -@deftypefn {Architecture Function} CORE_ADDR push_dummy_call (struct gdbarch *@var{gdbarch}, struct value *@var{function}, struct regcache *@var{regcache}, CORE_ADDR @var{bp_addr}, int @var{nargs}, struct value **@var{args}, CORE_ADDR @var{sp}, int @var{struct_return}, CORE_ADDR @var{struct_addr})
|
| -
|
| -This function sets up a dummy stack frame for the function about to be
|
| -called. @code{push_dummy_call} is given the arguments to be passed
|
| -and must copy them into registers or push them on to the stack as
|
| -appropriate for the ABI.
|
| -
|
| -@var{function} is a pointer to the function
|
| -that will be called and @var{regcache} the register cache from which
|
| -values should be obtained. @var{bp_addr} is the address to which the
|
| -function should return (which is breakpointed, so @value{GDBN} can
|
| -regain control, hence the name). @var{nargs} is the number of
|
| -arguments to pass and @var{args} an array containing the argument
|
| -values. @var{struct_return} is non-zero (true) if the function returns
|
| -a structure, and if so @var{struct_addr} is the address in which the
|
| -structure should be returned.
|
| -
|
| - After calling this function, @value{GDBN} will pass control to the
|
| -target at the address of the function, which will find the stack and
|
| -registers set up just as expected.
|
| -
|
| -The default value of this function is @code{NULL} (undefined). If the
|
| -function is not defined, then @value{GDBN} will not allow the user to
|
| -call functions within the target being debugged.
|
| -
|
| -@end deftypefn
|
| -
|
| -@deftypefn {Architecture Function} {struct frame_id} unwind_dummy_id (struct gdbarch *@var{gdbarch}, struct frame_info *@var{next_frame})
|
| -
|
| -This is the inverse of @code{push_dummy_call} which restores the stack
|
| -pointer and program counter after a call to evaluate a function using
|
| -a dummy stack frame. The result is a @code{@w{struct frame_id}}, which
|
| -contains the value of the stack pointer and program counter to be
|
| -used.
|
| -
|
| -The NEXT frame pointer is provided as argument,
|
| -@var{next_frame}. THIS frame is the frame of the dummy function,
|
| -which can be unwound, to yield the required stack pointer and program
|
| -counter from the PREVIOUS frame.
|
| -
|
| -The default value is @code{NULL} (undefined). If @code{push_dummy_call} is
|
| -defined, then this function should also be defined.
|
| -
|
| -@end deftypefn
|
| -
|
| -@deftypefn {Architecture Function} CORE_ADDR push_dummy_code (struct gdbarch *@var{gdbarch}, CORE_ADDR @var{sp}, CORE_ADDR @var{funaddr}, struct value **@var{args}, int @var{nargs}, struct type *@var{value_type}, CORE_ADDR *@var{real_pc}, CORE_ADDR *@var{bp_addr}, struct regcache *@var{regcache})
|
| -
|
| -If this function is not defined (its default value is @code{NULL}), a dummy
|
| -call will use the entry point of the currently loaded code on the
|
| -target as its return address. A temporary breakpoint will be set
|
| -there, so the location must be writable and have room for a
|
| -breakpoint.
|
| -
|
| -It is possible that this default is not suitable. It might not be
|
| -writable (in ROM possibly), or the ABI might require code to be
|
| -executed on return from a call to unwind the stack before the
|
| -breakpoint is encountered.
|
| -
|
| -If either of these is the case, then push_dummy_code should be defined
|
| -to push an instruction sequence onto the end of the stack to which the
|
| -dummy call should return.
|
| -
|
| -The arguments are essentially the same as those to
|
| -@code{push_dummy_call}. However the function is provided with the
|
| -type of the function result, @var{value_type}, @var{bp_addr} is used
|
| -to return a value (the address at which the breakpoint instruction
|
| -should be inserted) and @var{real pc} is used to specify the resume
|
| -address when starting the call sequence. The function should return
|
| -the updated innermost stack address.
|
| -
|
| -@quotation
|
| -@emph{Note:} This does require that code in the stack can be executed.
|
| -Some Harvard architectures may not allow this.
|
| -@end quotation
|
| -
|
| -@end deftypefn
|
| -
|
| -@node Adding support for debugging core files
|
| -@section Adding support for debugging core files
|
| -@cindex core files
|
| -
|
| -The prerequisite for adding core file support in @value{GDBN} is to have
|
| -core file support in BFD.
|
| -
|
| -Once BFD support is available, writing the apropriate
|
| -@code{regset_from_core_section} architecture function should be all
|
| -that is needed in order to add support for core files in @value{GDBN}.
|
| -
|
| -@node Defining Other Architecture Features
|
| -@section Defining Other Architecture Features
|
| -
|
| -This section describes other functions and values in @code{gdbarch},
|
| -together with some useful macros, that you can use to define the
|
| -target architecture.
|
| -
|
| -@table @code
|
| -
|
| -@item CORE_ADDR gdbarch_addr_bits_remove (@var{gdbarch}, @var{addr})
|
| -@findex gdbarch_addr_bits_remove
|
| -If a raw machine instruction address includes any bits that are not
|
| -really part of the address, then this function is used to zero those bits in
|
| -@var{addr}. This is only used for addresses of instructions, and even then not
|
| -in all contexts.
|
| -
|
| -For example, the two low-order bits of the PC on the Hewlett-Packard PA
|
| -2.0 architecture contain the privilege level of the corresponding
|
| -instruction. Since instructions must always be aligned on four-byte
|
| -boundaries, the processor masks out these bits to generate the actual
|
| -address of the instruction. @code{gdbarch_addr_bits_remove} would then for
|
| -example look like that:
|
| -@smallexample
|
| -arch_addr_bits_remove (CORE_ADDR addr)
|
| -@{
|
| - return (addr &= ~0x3);
|
| -@}
|
| -@end smallexample
|
| -
|
| -@item int address_class_name_to_type_flags (@var{gdbarch}, @var{name}, @var{type_flags_ptr})
|
| -@findex address_class_name_to_type_flags
|
| -If @var{name} is a valid address class qualifier name, set the @code{int}
|
| -referenced by @var{type_flags_ptr} to the mask representing the qualifier
|
| -and return 1. If @var{name} is not a valid address class qualifier name,
|
| -return 0.
|
| -
|
| -The value for @var{type_flags_ptr} should be one of
|
| -@code{TYPE_FLAG_ADDRESS_CLASS_1}, @code{TYPE_FLAG_ADDRESS_CLASS_2}, or
|
| -possibly some combination of these values or'd together.
|
| -@xref{Target Architecture Definition, , Address Classes}.
|
| -
|
| -@item int address_class_name_to_type_flags_p (@var{gdbarch})
|
| -@findex address_class_name_to_type_flags_p
|
| -Predicate which indicates whether @code{address_class_name_to_type_flags}
|
| -has been defined.
|
| -
|
| -@item int gdbarch_address_class_type_flags (@var{gdbarch}, @var{byte_size}, @var{dwarf2_addr_class})
|
| -@findex gdbarch_address_class_type_flags
|
| -Given a pointers byte size (as described by the debug information) and
|
| -the possible @code{DW_AT_address_class} value, return the type flags
|
| -used by @value{GDBN} to represent this address class. The value
|
| -returned should be one of @code{TYPE_FLAG_ADDRESS_CLASS_1},
|
| -@code{TYPE_FLAG_ADDRESS_CLASS_2}, or possibly some combination of these
|
| -values or'd together.
|
| -@xref{Target Architecture Definition, , Address Classes}.
|
| -
|
| -@item int gdbarch_address_class_type_flags_p (@var{gdbarch})
|
| -@findex gdbarch_address_class_type_flags_p
|
| -Predicate which indicates whether @code{gdbarch_address_class_type_flags_p} has
|
| -been defined.
|
| -
|
| -@item const char *gdbarch_address_class_type_flags_to_name (@var{gdbarch}, @var{type_flags})
|
| -@findex gdbarch_address_class_type_flags_to_name
|
| -Return the name of the address class qualifier associated with the type
|
| -flags given by @var{type_flags}.
|
| -
|
| -@item int gdbarch_address_class_type_flags_to_name_p (@var{gdbarch})
|
| -@findex gdbarch_address_class_type_flags_to_name_p
|
| -Predicate which indicates whether @code{gdbarch_address_class_type_flags_to_name} has been defined.
|
| -@xref{Target Architecture Definition, , Address Classes}.
|
| -
|
| -@item void gdbarch_address_to_pointer (@var{gdbarch}, @var{type}, @var{buf}, @var{addr})
|
| -@findex gdbarch_address_to_pointer
|
| -Store in @var{buf} a pointer of type @var{type} representing the address
|
| -@var{addr}, in the appropriate format for the current architecture.
|
| -This function may safely assume that @var{type} is either a pointer or a
|
| -C@t{++} reference type.
|
| -@xref{Target Architecture Definition, , Pointers Are Not Always Addresses}.
|
| -
|
| -@item int gdbarch_believe_pcc_promotion (@var{gdbarch})
|
| -@findex gdbarch_believe_pcc_promotion
|
| -Used to notify if the compiler promotes a @code{short} or @code{char}
|
| -parameter to an @code{int}, but still reports the parameter as its
|
| -original type, rather than the promoted type.
|
| -
|
| -@item gdbarch_bits_big_endian (@var{gdbarch})
|
| -@findex gdbarch_bits_big_endian
|
| -This is used if the numbering of bits in the targets does @strong{not} match
|
| -the endianism of the target byte order. A value of 1 means that the bits
|
| -are numbered in a big-endian bit order, 0 means little-endian.
|
| -
|
| -@item set_gdbarch_bits_big_endian (@var{gdbarch}, @var{bits_big_endian})
|
| -@findex set_gdbarch_bits_big_endian
|
| -Calling set_gdbarch_bits_big_endian with a value of 1 indicates that the
|
| -bits in the target are numbered in a big-endian bit order, 0 indicates
|
| -little-endian.
|
| -
|
| -@item BREAKPOINT
|
| -@findex BREAKPOINT
|
| -This is the character array initializer for the bit pattern to put into
|
| -memory where a breakpoint is set. Although it's common to use a trap
|
| -instruction for a breakpoint, it's not required; for instance, the bit
|
| -pattern could be an invalid instruction. The breakpoint must be no
|
| -longer than the shortest instruction of the architecture.
|
| -
|
| -@code{BREAKPOINT} has been deprecated in favor of
|
| -@code{gdbarch_breakpoint_from_pc}.
|
| -
|
| -@item BIG_BREAKPOINT
|
| -@itemx LITTLE_BREAKPOINT
|
| -@findex LITTLE_BREAKPOINT
|
| -@findex BIG_BREAKPOINT
|
| -Similar to BREAKPOINT, but used for bi-endian targets.
|
| -
|
| -@code{BIG_BREAKPOINT} and @code{LITTLE_BREAKPOINT} have been deprecated in
|
| -favor of @code{gdbarch_breakpoint_from_pc}.
|
| -
|
| -@item const gdb_byte *gdbarch_breakpoint_from_pc (@var{gdbarch}, @var{pcptr}, @var{lenptr})
|
| -@findex gdbarch_breakpoint_from_pc
|
| -@anchor{gdbarch_breakpoint_from_pc} Use the program counter to determine the
|
| -contents and size of a breakpoint instruction. It returns a pointer to
|
| -a static string of bytes that encode a breakpoint instruction, stores the
|
| -length of the string to @code{*@var{lenptr}}, and adjusts the program
|
| -counter (if necessary) to point to the actual memory location where the
|
| -breakpoint should be inserted. May return @code{NULL} to indicate that
|
| -software breakpoints are not supported.
|
| -
|
| -Although it is common to use a trap instruction for a breakpoint, it's
|
| -not required; for instance, the bit pattern could be an invalid
|
| -instruction. The breakpoint must be no longer than the shortest
|
| -instruction of the architecture.
|
| -
|
| -Provided breakpoint bytes can be also used by @code{bp_loc_is_permanent} to
|
| -detect permanent breakpoints. @code{gdbarch_breakpoint_from_pc} should return
|
| -an unchanged memory copy if it was called for a location with permanent
|
| -breakpoint as some architectures use breakpoint instructions containing
|
| -arbitrary parameter value.
|
| -
|
| -Replaces all the other @var{BREAKPOINT} macros.
|
| -
|
| -@item int gdbarch_memory_insert_breakpoint (@var{gdbarch}, @var{bp_tgt})
|
| -@itemx gdbarch_memory_remove_breakpoint (@var{gdbarch}, @var{bp_tgt})
|
| -@findex gdbarch_memory_remove_breakpoint
|
| -@findex gdbarch_memory_insert_breakpoint
|
| -Insert or remove memory based breakpoints. Reasonable defaults
|
| -(@code{default_memory_insert_breakpoint} and
|
| -@code{default_memory_remove_breakpoint} respectively) have been
|
| -provided so that it is not necessary to set these for most
|
| -architectures. Architectures which may want to set
|
| -@code{gdbarch_memory_insert_breakpoint} and @code{gdbarch_memory_remove_breakpoint} will likely have instructions that are oddly sized or are not stored in a
|
| -conventional manner.
|
| -
|
| -It may also be desirable (from an efficiency standpoint) to define
|
| -custom breakpoint insertion and removal routines if
|
| -@code{gdbarch_breakpoint_from_pc} needs to read the target's memory for some
|
| -reason.
|
| -
|
| -@item CORE_ADDR gdbarch_adjust_breakpoint_address (@var{gdbarch}, @var{bpaddr})
|
| -@findex gdbarch_adjust_breakpoint_address
|
| -@cindex breakpoint address adjusted
|
| -Given an address at which a breakpoint is desired, return a breakpoint
|
| -address adjusted to account for architectural constraints on
|
| -breakpoint placement. This method is not needed by most targets.
|
| -
|
| -The FR-V target (see @file{frv-tdep.c}) requires this method.
|
| -The FR-V is a VLIW architecture in which a number of RISC-like
|
| -instructions are grouped (packed) together into an aggregate
|
| -instruction or instruction bundle. When the processor executes
|
| -one of these bundles, the component instructions are executed
|
| -in parallel.
|
| -
|
| -In the course of optimization, the compiler may group instructions
|
| -from distinct source statements into the same bundle. The line number
|
| -information associated with one of the latter statements will likely
|
| -refer to some instruction other than the first one in the bundle. So,
|
| -if the user attempts to place a breakpoint on one of these latter
|
| -statements, @value{GDBN} must be careful to @emph{not} place the break
|
| -instruction on any instruction other than the first one in the bundle.
|
| -(Remember though that the instructions within a bundle execute
|
| -in parallel, so the @emph{first} instruction is the instruction
|
| -at the lowest address and has nothing to do with execution order.)
|
| -
|
| -The FR-V's @code{gdbarch_adjust_breakpoint_address} method will adjust a
|
| -breakpoint's address by scanning backwards for the beginning of
|
| -the bundle, returning the address of the bundle.
|
| -
|
| -Since the adjustment of a breakpoint may significantly alter a user's
|
| -expectation, @value{GDBN} prints a warning when an adjusted breakpoint
|
| -is initially set and each time that that breakpoint is hit.
|
| -
|
| -@item int gdbarch_call_dummy_location (@var{gdbarch})
|
| -@findex gdbarch_call_dummy_location
|
| -See the file @file{inferior.h}.
|
| -
|
| -This method has been replaced by @code{gdbarch_push_dummy_code}
|
| -(@pxref{gdbarch_push_dummy_code}).
|
| -
|
| -@item int gdbarch_cannot_fetch_register (@var{gdbarch}, @var{regum})
|
| -@findex gdbarch_cannot_fetch_register
|
| -This function should return nonzero if @var{regno} cannot be fetched
|
| -from an inferior process.
|
| -
|
| -@item int gdbarch_cannot_store_register (@var{gdbarch}, @var{regnum})
|
| -@findex gdbarch_cannot_store_register
|
| -This function should return nonzero if @var{regno} should not be
|
| -written to the target. This is often the case for program counters,
|
| -status words, and other special registers. This function returns 0 as
|
| -default so that @value{GDBN} will assume that all registers may be written.
|
| -
|
| -@item int gdbarch_convert_register_p (@var{gdbarch}, @var{regnum}, struct type *@var{type})
|
| -@findex gdbarch_convert_register_p
|
| -Return non-zero if register @var{regnum} represents data values of type
|
| -@var{type} in a non-standard form.
|
| -@xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}.
|
| -
|
| -@item int gdbarch_fp0_regnum (@var{gdbarch})
|
| -@findex gdbarch_fp0_regnum
|
| -This function returns the number of the first floating point register,
|
| -if the machine has such registers. Otherwise, it returns -1.
|
| -
|
| -@item CORE_ADDR gdbarch_decr_pc_after_break (@var{gdbarch})
|
| -@findex gdbarch_decr_pc_after_break
|
| -This function shall return the amount by which to decrement the PC after the
|
| -program encounters a breakpoint. This is often the number of bytes in
|
| -@code{BREAKPOINT}, though not always. For most targets this value will be 0.
|
| -
|
| -@item DISABLE_UNSETTABLE_BREAK (@var{addr})
|
| -@findex DISABLE_UNSETTABLE_BREAK
|
| -If defined, this should evaluate to 1 if @var{addr} is in a shared
|
| -library in which breakpoints cannot be set and so should be disabled.
|
| -
|
| -@item int gdbarch_dwarf2_reg_to_regnum (@var{gdbarch}, @var{dwarf2_regnr})
|
| -@findex gdbarch_dwarf2_reg_to_regnum
|
| -Convert DWARF2 register number @var{dwarf2_regnr} into @value{GDBN} regnum.
|
| -If not defined, no conversion will be performed.
|
| -
|
| -@item int gdbarch_ecoff_reg_to_regnum (@var{gdbarch}, @var{ecoff_regnr})
|
| -@findex gdbarch_ecoff_reg_to_regnum
|
| -Convert ECOFF register number @var{ecoff_regnr} into @value{GDBN} regnum. If
|
| -not defined, no conversion will be performed.
|
| -
|
| -@item GCC_COMPILED_FLAG_SYMBOL
|
| -@itemx GCC2_COMPILED_FLAG_SYMBOL
|
| -@findex GCC2_COMPILED_FLAG_SYMBOL
|
| -@findex GCC_COMPILED_FLAG_SYMBOL
|
| -If defined, these are the names of the symbols that @value{GDBN} will
|
| -look for to detect that GCC compiled the file. The default symbols
|
| -are @code{gcc_compiled.} and @code{gcc2_compiled.},
|
| -respectively. (Currently only defined for the Delta 68.)
|
| -
|
| -@item gdbarch_get_longjmp_target
|
| -@findex gdbarch_get_longjmp_target
|
| -This function determines the target PC address that @code{longjmp}
|
| -will jump to, assuming that we have just stopped at a @code{longjmp}
|
| -breakpoint. It takes a @code{CORE_ADDR *} as argument, and stores the
|
| -target PC value through this pointer. It examines the current state
|
| -of the machine as needed, typically by using a manually-determined
|
| -offset into the @code{jmp_buf}. (While we might like to get the offset
|
| -from the target's @file{jmpbuf.h}, that header file cannot be assumed
|
| -to be available when building a cross-debugger.)
|
| -
|
| -@item DEPRECATED_IBM6000_TARGET
|
| -@findex DEPRECATED_IBM6000_TARGET
|
| -Shows that we are configured for an IBM RS/6000 system. This
|
| -conditional should be eliminated (FIXME) and replaced by
|
| -feature-specific macros. It was introduced in haste and we are
|
| -repenting at leisure.
|
| -
|
| -@item I386_USE_GENERIC_WATCHPOINTS
|
| -An x86-based target can define this to use the generic x86 watchpoint
|
| -support; see @ref{Algorithms, I386_USE_GENERIC_WATCHPOINTS}.
|
| -
|
| -@item gdbarch_in_function_epilogue_p (@var{gdbarch}, @var{addr})
|
| -@findex gdbarch_in_function_epilogue_p
|
| -Returns non-zero if the given @var{addr} is in the epilogue of a function.
|
| -The epilogue of a function is defined as the part of a function where
|
| -the stack frame of the function already has been destroyed up to the
|
| -final `return from function call' instruction.
|
| -
|
| -@item int gdbarch_in_solib_return_trampoline (@var{gdbarch}, @var{pc}, @var{name})
|
| -@findex gdbarch_in_solib_return_trampoline
|
| -Define this function to return nonzero if the program is stopped in the
|
| -trampoline that returns from a shared library.
|
| -
|
| -@item target_so_ops.in_dynsym_resolve_code (@var{pc})
|
| -@findex in_dynsym_resolve_code
|
| -Define this to return nonzero if the program is stopped in the
|
| -dynamic linker.
|
| -
|
| -@item SKIP_SOLIB_RESOLVER (@var{pc})
|
| -@findex SKIP_SOLIB_RESOLVER
|
| -Define this to evaluate to the (nonzero) address at which execution
|
| -should continue to get past the dynamic linker's symbol resolution
|
| -function. A zero value indicates that it is not important or necessary
|
| -to set a breakpoint to get through the dynamic linker and that single
|
| -stepping will suffice.
|
| -
|
| -@item CORE_ADDR gdbarch_integer_to_address (@var{gdbarch}, @var{type}, @var{buf})
|
| -@findex gdbarch_integer_to_address
|
| -@cindex converting integers to addresses
|
| -Define this when the architecture needs to handle non-pointer to address
|
| -conversions specially. Converts that value to an address according to
|
| -the current architectures conventions.
|
| -
|
| -@emph{Pragmatics: When the user copies a well defined expression from
|
| -their source code and passes it, as a parameter, to @value{GDBN}'s
|
| -@code{print} command, they should get the same value as would have been
|
| -computed by the target program. Any deviation from this rule can cause
|
| -major confusion and annoyance, and needs to be justified carefully. In
|
| -other words, @value{GDBN} doesn't really have the freedom to do these
|
| -conversions in clever and useful ways. It has, however, been pointed
|
| -out that users aren't complaining about how @value{GDBN} casts integers
|
| -to pointers; they are complaining that they can't take an address from a
|
| -disassembly listing and give it to @code{x/i}. Adding an architecture
|
| -method like @code{gdbarch_integer_to_address} certainly makes it possible for
|
| -@value{GDBN} to ``get it right'' in all circumstances.}
|
| -
|
| -@xref{Target Architecture Definition, , Pointers Are Not Always
|
| -Addresses}.
|
| -
|
| -@item CORE_ADDR gdbarch_pointer_to_address (@var{gdbarch}, @var{type}, @var{buf})
|
| -@findex gdbarch_pointer_to_address
|
| -Assume that @var{buf} holds a pointer of type @var{type}, in the
|
| -appropriate format for the current architecture. Return the byte
|
| -address the pointer refers to.
|
| -@xref{Target Architecture Definition, , Pointers Are Not Always Addresses}.
|
| -
|
| -@item void gdbarch_register_to_value(@var{gdbarch}, @var{frame}, @var{regnum}, @var{type}, @var{fur})
|
| -@findex gdbarch_register_to_value
|
| -Convert the raw contents of register @var{regnum} into a value of type
|
| -@var{type}.
|
| -@xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}.
|
| -
|
| -@item REGISTER_CONVERT_TO_VIRTUAL(@var{reg}, @var{type}, @var{from}, @var{to})
|
| -@findex REGISTER_CONVERT_TO_VIRTUAL
|
| -Convert the value of register @var{reg} from its raw form to its virtual
|
| -form.
|
| -@xref{Target Architecture Definition, , Raw and Virtual Register Representations}.
|
| -
|
| -@item REGISTER_CONVERT_TO_RAW(@var{type}, @var{reg}, @var{from}, @var{to})
|
| -@findex REGISTER_CONVERT_TO_RAW
|
| -Convert the value of register @var{reg} from its virtual form to its raw
|
| -form.
|
| -@xref{Target Architecture Definition, , Raw and Virtual Register Representations}.
|
| -
|
| -@item const struct regset *regset_from_core_section (struct gdbarch * @var{gdbarch}, const char * @var{sect_name}, size_t @var{sect_size})
|
| -@findex regset_from_core_section
|
| -Return the appropriate register set for a core file section with name
|
| -@var{sect_name} and size @var{sect_size}.
|
| -
|
| -@item SOFTWARE_SINGLE_STEP_P()
|
| -@findex SOFTWARE_SINGLE_STEP_P
|
| -Define this as 1 if the target does not have a hardware single-step
|
| -mechanism. The macro @code{SOFTWARE_SINGLE_STEP} must also be defined.
|
| -
|
| -@item SOFTWARE_SINGLE_STEP(@var{signal}, @var{insert_breakpoints_p})
|
| -@findex SOFTWARE_SINGLE_STEP
|
| -A function that inserts or removes (depending on
|
| -@var{insert_breakpoints_p}) breakpoints at each possible destinations of
|
| -the next instruction. See @file{sparc-tdep.c} and @file{rs6000-tdep.c}
|
| -for examples.
|
| -
|
| -@item set_gdbarch_sofun_address_maybe_missing (@var{gdbarch}, @var{set})
|
| -@findex set_gdbarch_sofun_address_maybe_missing
|
| -Somebody clever observed that, the more actual addresses you have in the
|
| -debug information, the more time the linker has to spend relocating
|
| -them. So whenever there's some other way the debugger could find the
|
| -address it needs, you should omit it from the debug info, to make
|
| -linking faster.
|
| -
|
| -Calling @code{set_gdbarch_sofun_address_maybe_missing} with a non-zero
|
| -argument @var{set} indicates that a particular set of hacks of this sort
|
| -are in use, affecting @code{N_SO} and @code{N_FUN} entries in stabs-format
|
| -debugging information. @code{N_SO} stabs mark the beginning and ending
|
| -addresses of compilation units in the text segment. @code{N_FUN} stabs
|
| -mark the starts and ends of functions.
|
| -
|
| -In this case, @value{GDBN} assumes two things:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -@code{N_FUN} stabs have an address of zero. Instead of using those
|
| -addresses, you should find the address where the function starts by
|
| -taking the function name from the stab, and then looking that up in the
|
| -minsyms (the linker/assembler symbol table). In other words, the stab
|
| -has the name, and the linker/assembler symbol table is the only place
|
| -that carries the address.
|
| -
|
| -@item
|
| -@code{N_SO} stabs have an address of zero, too. You just look at the
|
| -@code{N_FUN} stabs that appear before and after the @code{N_SO} stab, and
|
| -guess the starting and ending addresses of the compilation unit from them.
|
| -@end itemize
|
| -
|
| -@item int gdbarch_stabs_argument_has_addr (@var{gdbarch}, @var{type})
|
| -@findex gdbarch_stabs_argument_has_addr
|
| -@anchor{gdbarch_stabs_argument_has_addr} Define this function to return
|
| -nonzero if a function argument of type @var{type} is passed by reference
|
| -instead of value.
|
| -
|
| -@item CORE_ADDR gdbarch_push_dummy_call (@var{gdbarch}, @var{function}, @var{regcache}, @var{bp_addr}, @var{nargs}, @var{args}, @var{sp}, @var{struct_return}, @var{struct_addr})
|
| -@findex gdbarch_push_dummy_call
|
| -@anchor{gdbarch_push_dummy_call} Define this to push the dummy frame's call to
|
| -the inferior function onto the stack. In addition to pushing @var{nargs}, the
|
| -code should push @var{struct_addr} (when @var{struct_return} is non-zero), and
|
| -the return address (@var{bp_addr}).
|
| -
|
| -@var{function} is a pointer to a @code{struct value}; on architectures that use
|
| -function descriptors, this contains the function descriptor value.
|
| -
|
| -Returns the updated top-of-stack pointer.
|
| -
|
| -@item CORE_ADDR gdbarch_push_dummy_code (@var{gdbarch}, @var{sp}, @var{funaddr}, @var{using_gcc}, @var{args}, @var{nargs}, @var{value_type}, @var{real_pc}, @var{bp_addr}, @var{regcache})
|
| -@findex gdbarch_push_dummy_code
|
| -@anchor{gdbarch_push_dummy_code} Given a stack based call dummy, push the
|
| -instruction sequence (including space for a breakpoint) to which the
|
| -called function should return.
|
| -
|
| -Set @var{bp_addr} to the address at which the breakpoint instruction
|
| -should be inserted, @var{real_pc} to the resume address when starting
|
| -the call sequence, and return the updated inner-most stack address.
|
| -
|
| -By default, the stack is grown sufficient to hold a frame-aligned
|
| -(@pxref{frame_align}) breakpoint, @var{bp_addr} is set to the address
|
| -reserved for that breakpoint, and @var{real_pc} set to @var{funaddr}.
|
| -
|
| -This method replaces @w{@code{gdbarch_call_dummy_location (@var{gdbarch})}}.
|
| -
|
| -@item int gdbarch_sdb_reg_to_regnum (@var{gdbarch}, @var{sdb_regnr})
|
| -@findex gdbarch_sdb_reg_to_regnum
|
| -Use this function to convert sdb register @var{sdb_regnr} into @value{GDBN}
|
| -regnum. If not defined, no conversion will be done.
|
| -
|
| -@item enum return_value_convention gdbarch_return_value (struct gdbarch *@var{gdbarch}, struct type *@var{valtype}, struct regcache *@var{regcache}, void *@var{readbuf}, const void *@var{writebuf})
|
| -@findex gdbarch_return_value
|
| -@anchor{gdbarch_return_value} Given a function with a return-value of
|
| -type @var{rettype}, return which return-value convention that function
|
| -would use.
|
| -
|
| -@value{GDBN} currently recognizes two function return-value conventions:
|
| -@code{RETURN_VALUE_REGISTER_CONVENTION} where the return value is found
|
| -in registers; and @code{RETURN_VALUE_STRUCT_CONVENTION} where the return
|
| -value is found in memory and the address of that memory location is
|
| -passed in as the function's first parameter.
|
| -
|
| -If the register convention is being used, and @var{writebuf} is
|
| -non-@code{NULL}, also copy the return-value in @var{writebuf} into
|
| -@var{regcache}.
|
| -
|
| -If the register convention is being used, and @var{readbuf} is
|
| -non-@code{NULL}, also copy the return value from @var{regcache} into
|
| -@var{readbuf} (@var{regcache} contains a copy of the registers from the
|
| -just returned function).
|
| -
|
| -@emph{Maintainer note: This method replaces separate predicate, extract,
|
| -store methods. By having only one method, the logic needed to determine
|
| -the return-value convention need only be implemented in one place. If
|
| -@value{GDBN} were written in an @sc{oo} language, this method would
|
| -instead return an object that knew how to perform the register
|
| -return-value extract and store.}
|
| -
|
| -@emph{Maintainer note: This method does not take a @var{gcc_p}
|
| -parameter, and such a parameter should not be added. If an architecture
|
| -that requires per-compiler or per-function information be identified,
|
| -then the replacement of @var{rettype} with @code{struct value}
|
| -@var{function} should be pursued.}
|
| -
|
| -@emph{Maintainer note: The @var{regcache} parameter limits this methods
|
| -to the inner most frame. While replacing @var{regcache} with a
|
| -@code{struct frame_info} @var{frame} parameter would remove that
|
| -limitation there has yet to be a demonstrated need for such a change.}
|
| -
|
| -@item void gdbarch_skip_permanent_breakpoint (@var{gdbarch}, @var{regcache})
|
| -@findex gdbarch_skip_permanent_breakpoint
|
| -Advance the inferior's PC past a permanent breakpoint. @value{GDBN} normally
|
| -steps over a breakpoint by removing it, stepping one instruction, and
|
| -re-inserting the breakpoint. However, permanent breakpoints are
|
| -hardwired into the inferior, and can't be removed, so this strategy
|
| -doesn't work. Calling @code{gdbarch_skip_permanent_breakpoint} adjusts the
|
| -processor's state so that execution will resume just after the breakpoint.
|
| -This function does the right thing even when the breakpoint is in the delay slot
|
| -of a branch or jump.
|
| -
|
| -@item CORE_ADDR gdbarch_skip_trampoline_code (@var{gdbarch}, @var{frame}, @var{pc})
|
| -@findex gdbarch_skip_trampoline_code
|
| -If the target machine has trampoline code that sits between callers and
|
| -the functions being called, then define this function to return a new PC
|
| -that is at the start of the real function.
|
| -
|
| -@item int gdbarch_deprecated_fp_regnum (@var{gdbarch})
|
| -@findex gdbarch_deprecated_fp_regnum
|
| -If the frame pointer is in a register, use this function to return the
|
| -number of that register.
|
| -
|
| -@item int gdbarch_stab_reg_to_regnum (@var{gdbarch}, @var{stab_regnr})
|
| -@findex gdbarch_stab_reg_to_regnum
|
| -Use this function to convert stab register @var{stab_regnr} into @value{GDBN}
|
| -regnum. If not defined, no conversion will be done.
|
| -
|
| -@item TARGET_CHAR_BIT
|
| -@findex TARGET_CHAR_BIT
|
| -Number of bits in a char; defaults to 8.
|
| -
|
| -@item int gdbarch_char_signed (@var{gdbarch})
|
| -@findex gdbarch_char_signed
|
| -Non-zero if @code{char} is normally signed on this architecture; zero if
|
| -it should be unsigned.
|
| -
|
| -The ISO C standard requires the compiler to treat @code{char} as
|
| -equivalent to either @code{signed char} or @code{unsigned char}; any
|
| -character in the standard execution set is supposed to be positive.
|
| -Most compilers treat @code{char} as signed, but @code{char} is unsigned
|
| -on the IBM S/390, RS6000, and PowerPC targets.
|
| -
|
| -@item int gdbarch_double_bit (@var{gdbarch})
|
| -@findex gdbarch_double_bit
|
| -Number of bits in a double float; defaults to @w{@code{8 * TARGET_CHAR_BIT}}.
|
| -
|
| -@item int gdbarch_float_bit (@var{gdbarch})
|
| -@findex gdbarch_float_bit
|
| -Number of bits in a float; defaults to @w{@code{4 * TARGET_CHAR_BIT}}.
|
| -
|
| -@item int gdbarch_int_bit (@var{gdbarch})
|
| -@findex gdbarch_int_bit
|
| -Number of bits in an integer; defaults to @w{@code{4 * TARGET_CHAR_BIT}}.
|
| -
|
| -@item int gdbarch_long_bit (@var{gdbarch})
|
| -@findex gdbarch_long_bit
|
| -Number of bits in a long integer; defaults to @w{@code{4 * TARGET_CHAR_BIT}}.
|
| -
|
| -@item int gdbarch_long_double_bit (@var{gdbarch})
|
| -@findex gdbarch_long_double_bit
|
| -Number of bits in a long double float;
|
| -defaults to @w{@code{2 * gdbarch_double_bit (@var{gdbarch})}}.
|
| -
|
| -@item int gdbarch_long_long_bit (@var{gdbarch})
|
| -@findex gdbarch_long_long_bit
|
| -Number of bits in a long long integer; defaults to
|
| -@w{@code{2 * gdbarch_long_bit (@var{gdbarch})}}.
|
| -
|
| -@item int gdbarch_ptr_bit (@var{gdbarch})
|
| -@findex gdbarch_ptr_bit
|
| -Number of bits in a pointer; defaults to
|
| -@w{@code{gdbarch_int_bit (@var{gdbarch})}}.
|
| -
|
| -@item int gdbarch_short_bit (@var{gdbarch})
|
| -@findex gdbarch_short_bit
|
| -Number of bits in a short integer; defaults to @w{@code{2 * TARGET_CHAR_BIT}}.
|
| -
|
| -@item void gdbarch_virtual_frame_pointer (@var{gdbarch}, @var{pc}, @var{frame_regnum}, @var{frame_offset})
|
| -@findex gdbarch_virtual_frame_pointer
|
| -Returns a @code{(@var{register}, @var{offset})} pair representing the virtual
|
| -frame pointer in use at the code address @var{pc}. If virtual frame
|
| -pointers are not used, a default definition simply returns
|
| -@code{gdbarch_deprecated_fp_regnum} (or @code{gdbarch_sp_regnum}, if
|
| -no frame pointer is defined), with an offset of zero.
|
| -
|
| -@c need to explain virtual frame pointers, they are recorded in agent
|
| -@c expressions for tracepoints
|
| -
|
| -@item TARGET_HAS_HARDWARE_WATCHPOINTS
|
| -If non-zero, the target has support for hardware-assisted
|
| -watchpoints. @xref{Algorithms, watchpoints}, for more details and
|
| -other related macros.
|
| -
|
| -@item int gdbarch_print_insn (@var{gdbarch}, @var{vma}, @var{info})
|
| -@findex gdbarch_print_insn
|
| -This is the function used by @value{GDBN} to print an assembly
|
| -instruction. It prints the instruction at address @var{vma} in
|
| -debugged memory and returns the length of the instruction, in bytes.
|
| -This usually points to a function in the @code{opcodes} library
|
| -(@pxref{Support Libraries, ,Opcodes}). @var{info} is a structure (of
|
| -type @code{disassemble_info}) defined in the header file
|
| -@file{include/dis-asm.h}, and used to pass information to the
|
| -instruction decoding routine.
|
| -
|
| -@item frame_id gdbarch_dummy_id (@var{gdbarch}, @var{frame})
|
| -@findex gdbarch_dummy_id
|
| -@anchor{gdbarch_dummy_id} Given @var{frame} return a @w{@code{struct
|
| -frame_id}} that uniquely identifies an inferior function call's dummy
|
| -frame. The value returned must match the dummy frame stack value
|
| -previously saved by @code{call_function_by_hand}.
|
| -
|
| -@item void gdbarch_value_to_register (@var{gdbarch}, @var{frame}, @var{type}, @var{buf})
|
| -@findex gdbarch_value_to_register
|
| -Convert a value of type @var{type} into the raw contents of a register.
|
| -@xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}.
|
| -
|
| -@end table
|
| -
|
| -Motorola M68K target conditionals.
|
| -
|
| -@ftable @code
|
| -@item BPT_VECTOR
|
| -Define this to be the 4-bit location of the breakpoint trap vector. If
|
| -not defined, it will default to @code{0xf}.
|
| -
|
| -@item REMOTE_BPT_VECTOR
|
| -Defaults to @code{1}.
|
| -
|
| -@end ftable
|
| -
|
| -@node Adding a New Target
|
| -@section Adding a New Target
|
| -
|
| -@cindex adding a target
|
| -The following files add a target to @value{GDBN}:
|
| -
|
| -@table @file
|
| -@cindex target dependent files
|
| -
|
| -@item gdb/@var{ttt}-tdep.c
|
| -Contains any miscellaneous code required for this target machine. On
|
| -some machines it doesn't exist at all.
|
| -
|
| -@item gdb/@var{arch}-tdep.c
|
| -@itemx gdb/@var{arch}-tdep.h
|
| -This is required to describe the basic layout of the target machine's
|
| -processor chip (registers, stack, etc.). It can be shared among many
|
| -targets that use the same processor architecture.
|
| -
|
| -@end table
|
| -
|
| -(Target header files such as
|
| -@file{gdb/config/@var{arch}/tm-@var{ttt}.h},
|
| -@file{gdb/config/@var{arch}/tm-@var{arch}.h}, and
|
| -@file{config/tm-@var{os}.h} are no longer used.)
|
| -
|
| -@findex _initialize_@var{arch}_tdep
|
| -A @value{GDBN} description for a new architecture, arch is created by
|
| -defining a global function @code{_initialize_@var{arch}_tdep}, by
|
| -convention in the source file @file{@var{arch}-tdep.c}. For
|
| -example, in the case of the OpenRISC 1000, this function is called
|
| -@code{_initialize_or1k_tdep} and is found in the file
|
| -@file{or1k-tdep.c}.
|
| -
|
| -The object file resulting from compiling this source file, which will
|
| -contain the implementation of the
|
| -@code{_initialize_@var{arch}_tdep} function is specified in the
|
| -@value{GDBN} @file{configure.tgt} file, which includes a large case
|
| -statement pattern matching against the @code{--target} option of the
|
| -@kbd{configure} script.
|
| -
|
| -@quotation
|
| -@emph{Note:} If the architecture requires multiple source files, the
|
| -corresponding binaries should be included in
|
| -@file{configure.tgt}. However if there are header files, the
|
| -dependencies on these will not be picked up from the entries in
|
| -@file{configure.tgt}. The @file{Makefile.in} file will need extending to
|
| -show these dependencies.
|
| -@end quotation
|
| -
|
| -@findex gdbarch_register
|
| -A new struct gdbarch, defining the new architecture, is created within
|
| -the @code{_initialize_@var{arch}_tdep} function by calling
|
| -@code{gdbarch_register}:
|
| -
|
| -@smallexample
|
| -void gdbarch_register (enum bfd_architecture architecture,
|
| - gdbarch_init_ftype *init_func,
|
| - gdbarch_dump_tdep_ftype *tdep_dump_func);
|
| -@end smallexample
|
| -
|
| -This function has been described fully in an earlier
|
| -section. @xref{How an Architecture is Represented, , How an
|
| -Architecture is Represented}.
|
| -
|
| -The new @code{@w{struct gdbarch}} should contain implementations of
|
| -the necessary functions (described in the previous sections) to
|
| -describe the basic layout of the target machine's processor chip
|
| -(registers, stack, etc.). It can be shared among many targets that use
|
| -the same processor architecture.
|
| -
|
| -@node Target Descriptions
|
| -@chapter Target Descriptions
|
| -@cindex target descriptions
|
| -
|
| -The target architecture definition (@pxref{Target Architecture Definition})
|
| -contains @value{GDBN}'s hard-coded knowledge about an architecture. For
|
| -some platforms, it is handy to have more flexible knowledge about a specific
|
| -instance of the architecture---for instance, a processor or development board.
|
| -@dfn{Target descriptions} provide a mechanism for the user to tell @value{GDBN}
|
| -more about what their target supports, or for the target to tell @value{GDBN}
|
| -directly.
|
| -
|
| -For details on writing, automatically supplying, and manually selecting
|
| -target descriptions, see @ref{Target Descriptions, , , gdb,
|
| -Debugging with @value{GDBN}}. This section will cover some related
|
| -topics about the @value{GDBN} internals.
|
| -
|
| -@menu
|
| -* Target Descriptions Implementation::
|
| -* Adding Target Described Register Support::
|
| -@end menu
|
| -
|
| -@node Target Descriptions Implementation
|
| -@section Target Descriptions Implementation
|
| -@cindex target descriptions, implementation
|
| -
|
| -Before @value{GDBN} connects to a new target, or runs a new program on
|
| -an existing target, it discards any existing target description and
|
| -reverts to a default gdbarch. Then, after connecting, it looks for a
|
| -new target description by calling @code{target_find_description}.
|
| -
|
| -A description may come from a user specified file (XML), the remote
|
| -@samp{qXfer:features:read} packet (also XML), or from any custom
|
| -@code{to_read_description} routine in the target vector. For instance,
|
| -the remote target supports guessing whether a MIPS target is 32-bit or
|
| -64-bit based on the size of the @samp{g} packet.
|
| -
|
| -If any target description is found, @value{GDBN} creates a new gdbarch
|
| -incorporating the description by calling @code{gdbarch_update_p}. Any
|
| -@samp{<architecture>} element is handled first, to determine which
|
| -architecture's gdbarch initialization routine is called to create the
|
| -new architecture. Then the initialization routine is called, and has
|
| -a chance to adjust the constructed architecture based on the contents
|
| -of the target description. For instance, it can recognize any
|
| -properties set by a @code{to_read_description} routine. Also
|
| -see @ref{Adding Target Described Register Support}.
|
| -
|
| -@node Adding Target Described Register Support
|
| -@section Adding Target Described Register Support
|
| -@cindex target descriptions, adding register support
|
| -
|
| -Target descriptions can report additional registers specific to an
|
| -instance of the target. But it takes a little work in the architecture
|
| -specific routines to support this.
|
| -
|
| -A target description must either have no registers or a complete
|
| -set---this avoids complexity in trying to merge standard registers
|
| -with the target defined registers. It is the architecture's
|
| -responsibility to validate that a description with registers has
|
| -everything it needs. To keep architecture code simple, the same
|
| -mechanism is used to assign fixed internal register numbers to
|
| -standard registers.
|
| -
|
| -If @code{tdesc_has_registers} returns 1, the description contains
|
| -registers. The architecture's @code{gdbarch_init} routine should:
|
| -
|
| -@itemize @bullet
|
| -
|
| -@item
|
| -Call @code{tdesc_data_alloc} to allocate storage, early, before
|
| -searching for a matching gdbarch or allocating a new one.
|
| -
|
| -@item
|
| -Use @code{tdesc_find_feature} to locate standard features by name.
|
| -
|
| -@item
|
| -Use @code{tdesc_numbered_register} and @code{tdesc_numbered_register_choices}
|
| -to locate the expected registers in the standard features.
|
| -
|
| -@item
|
| -Return @code{NULL} if a required feature is missing, or if any standard
|
| -feature is missing expected registers. This will produce a warning that
|
| -the description was incomplete.
|
| -
|
| -@item
|
| -Free the allocated data before returning, unless @code{tdesc_use_registers}
|
| -is called.
|
| -
|
| -@item
|
| -Call @code{set_gdbarch_num_regs} as usual, with a number higher than any
|
| -fixed number passed to @code{tdesc_numbered_register}.
|
| -
|
| -@item
|
| -Call @code{tdesc_use_registers} after creating a new gdbarch, before
|
| -returning it.
|
| -
|
| -@end itemize
|
| -
|
| -After @code{tdesc_use_registers} has been called, the architecture's
|
| -@code{register_name}, @code{register_type}, and @code{register_reggroup_p}
|
| -routines will not be called; that information will be taken from
|
| -the target description. @code{num_regs} may be increased to account
|
| -for any additional registers in the description.
|
| -
|
| -Pseudo-registers require some extra care:
|
| -
|
| -@itemize @bullet
|
| -
|
| -@item
|
| -Using @code{tdesc_numbered_register} allows the architecture to give
|
| -constant register numbers to standard architectural registers, e.g.@:
|
| -as an @code{enum} in @file{@var{arch}-tdep.h}. But because
|
| -pseudo-registers are always numbered above @code{num_regs},
|
| -which may be increased by the description, constant numbers
|
| -can not be used for pseudos. They must be numbered relative to
|
| -@code{num_regs} instead.
|
| -
|
| -@item
|
| -The description will not describe pseudo-registers, so the
|
| -architecture must call @code{set_tdesc_pseudo_register_name},
|
| -@code{set_tdesc_pseudo_register_type}, and
|
| -@code{set_tdesc_pseudo_register_reggroup_p} to supply routines
|
| -describing pseudo registers. These routines will be passed
|
| -internal register numbers, so the same routines used for the
|
| -gdbarch equivalents are usually suitable.
|
| -
|
| -@end itemize
|
| -
|
| -
|
| -@node Target Vector Definition
|
| -
|
| -@chapter Target Vector Definition
|
| -@cindex target vector
|
| -
|
| -The target vector defines the interface between @value{GDBN}'s
|
| -abstract handling of target systems, and the nitty-gritty code that
|
| -actually exercises control over a process or a serial port.
|
| -@value{GDBN} includes some 30-40 different target vectors; however,
|
| -each configuration of @value{GDBN} includes only a few of them.
|
| -
|
| -@menu
|
| -* Managing Execution State::
|
| -* Existing Targets::
|
| -@end menu
|
| -
|
| -@node Managing Execution State
|
| -@section Managing Execution State
|
| -@cindex execution state
|
| -
|
| -A target vector can be completely inactive (not pushed on the target
|
| -stack), active but not running (pushed, but not connected to a fully
|
| -manifested inferior), or completely active (pushed, with an accessible
|
| -inferior). Most targets are only completely inactive or completely
|
| -active, but some support persistent connections to a target even
|
| -when the target has exited or not yet started.
|
| -
|
| -For example, connecting to the simulator using @code{target sim} does
|
| -not create a running program. Neither registers nor memory are
|
| -accessible until @code{run}. Similarly, after @code{kill}, the
|
| -program can not continue executing. But in both cases @value{GDBN}
|
| -remains connected to the simulator, and target-specific commands
|
| -are directed to the simulator.
|
| -
|
| -A target which only supports complete activation should push itself
|
| -onto the stack in its @code{to_open} routine (by calling
|
| -@code{push_target}), and unpush itself from the stack in its
|
| -@code{to_mourn_inferior} routine (by calling @code{unpush_target}).
|
| -
|
| -A target which supports both partial and complete activation should
|
| -still call @code{push_target} in @code{to_open}, but not call
|
| -@code{unpush_target} in @code{to_mourn_inferior}. Instead, it should
|
| -call either @code{target_mark_running} or @code{target_mark_exited}
|
| -in its @code{to_open}, depending on whether the target is fully active
|
| -after connection. It should also call @code{target_mark_running} any
|
| -time the inferior becomes fully active (e.g.@: in
|
| -@code{to_create_inferior} and @code{to_attach}), and
|
| -@code{target_mark_exited} when the inferior becomes inactive (in
|
| -@code{to_mourn_inferior}). The target should also make sure to call
|
| -@code{target_mourn_inferior} from its @code{to_kill}, to return the
|
| -target to inactive state.
|
| -
|
| -@node Existing Targets
|
| -@section Existing Targets
|
| -@cindex targets
|
| -
|
| -@subsection File Targets
|
| -
|
| -Both executables and core files have target vectors.
|
| -
|
| -@subsection Standard Protocol and Remote Stubs
|
| -
|
| -@value{GDBN}'s file @file{remote.c} talks a serial protocol to code that
|
| -runs in the target system. @value{GDBN} provides several sample
|
| -@dfn{stubs} that can be integrated into target programs or operating
|
| -systems for this purpose; they are named @file{@var{cpu}-stub.c}. Many
|
| -operating systems, embedded targets, emulators, and simulators already
|
| -have a @value{GDBN} stub built into them, and maintenance of the remote
|
| -protocol must be careful to preserve compatibility.
|
| -
|
| -The @value{GDBN} user's manual describes how to put such a stub into
|
| -your target code. What follows is a discussion of integrating the
|
| -SPARC stub into a complicated operating system (rather than a simple
|
| -program), by Stu Grossman, the author of this stub.
|
| -
|
| -The trap handling code in the stub assumes the following upon entry to
|
| -@code{trap_low}:
|
| -
|
| -@enumerate
|
| -@item
|
| -%l1 and %l2 contain pc and npc respectively at the time of the trap;
|
| -
|
| -@item
|
| -traps are disabled;
|
| -
|
| -@item
|
| -you are in the correct trap window.
|
| -@end enumerate
|
| -
|
| -As long as your trap handler can guarantee those conditions, then there
|
| -is no reason why you shouldn't be able to ``share'' traps with the stub.
|
| -The stub has no requirement that it be jumped to directly from the
|
| -hardware trap vector. That is why it calls @code{exceptionHandler()},
|
| -which is provided by the external environment. For instance, this could
|
| -set up the hardware traps to actually execute code which calls the stub
|
| -first, and then transfers to its own trap handler.
|
| -
|
| -For the most point, there probably won't be much of an issue with
|
| -``sharing'' traps, as the traps we use are usually not used by the kernel,
|
| -and often indicate unrecoverable error conditions. Anyway, this is all
|
| -controlled by a table, and is trivial to modify. The most important
|
| -trap for us is for @code{ta 1}. Without that, we can't single step or
|
| -do breakpoints. Everything else is unnecessary for the proper operation
|
| -of the debugger/stub.
|
| -
|
| -From reading the stub, it's probably not obvious how breakpoints work.
|
| -They are simply done by deposit/examine operations from @value{GDBN}.
|
| -
|
| -@subsection ROM Monitor Interface
|
| -
|
| -@subsection Custom Protocols
|
| -
|
| -@subsection Transport Layer
|
| -
|
| -@subsection Builtin Simulator
|
| -
|
| -
|
| -@node Native Debugging
|
| -
|
| -@chapter Native Debugging
|
| -@cindex native debugging
|
| -
|
| -Several files control @value{GDBN}'s configuration for native support:
|
| -
|
| -@table @file
|
| -@vindex NATDEPFILES
|
| -@item gdb/config/@var{arch}/@var{xyz}.mh
|
| -Specifies Makefile fragments needed by a @emph{native} configuration on
|
| -machine @var{xyz}. In particular, this lists the required
|
| -native-dependent object files, by defining @samp{NATDEPFILES=@dots{}}.
|
| -Also specifies the header file which describes native support on
|
| -@var{xyz}, by defining @samp{NAT_FILE= nm-@var{xyz}.h}. You can also
|
| -define @samp{NAT_CFLAGS}, @samp{NAT_ADD_FILES}, @samp{NAT_CLIBS},
|
| -@samp{NAT_CDEPS}, @samp{NAT_GENERATED_FILES}, etc.; see @file{Makefile.in}.
|
| -
|
| -@emph{Maintainer's note: The @file{.mh} suffix is because this file
|
| -originally contained @file{Makefile} fragments for hosting @value{GDBN}
|
| -on machine @var{xyz}. While the file is no longer used for this
|
| -purpose, the @file{.mh} suffix remains. Perhaps someone will
|
| -eventually rename these fragments so that they have a @file{.mn}
|
| -suffix.}
|
| -
|
| -@item gdb/config/@var{arch}/nm-@var{xyz}.h
|
| -(@file{nm.h} is a link to this file, created by @code{configure}). Contains C
|
| -macro definitions describing the native system environment, such as
|
| -child process control and core file support.
|
| -
|
| -@item gdb/@var{xyz}-nat.c
|
| -Contains any miscellaneous C code required for this native support of
|
| -this machine. On some machines it doesn't exist at all.
|
| -@end table
|
| -
|
| -There are some ``generic'' versions of routines that can be used by
|
| -various systems. These can be customized in various ways by macros
|
| -defined in your @file{nm-@var{xyz}.h} file. If these routines work for
|
| -the @var{xyz} host, you can just include the generic file's name (with
|
| -@samp{.o}, not @samp{.c}) in @code{NATDEPFILES}.
|
| -
|
| -Otherwise, if your machine needs custom support routines, you will need
|
| -to write routines that perform the same functions as the generic file.
|
| -Put them into @file{@var{xyz}-nat.c}, and put @file{@var{xyz}-nat.o}
|
| -into @code{NATDEPFILES}.
|
| -
|
| -@table @file
|
| -@item inftarg.c
|
| -This contains the @emph{target_ops vector} that supports Unix child
|
| -processes on systems which use ptrace and wait to control the child.
|
| -
|
| -@item procfs.c
|
| -This contains the @emph{target_ops vector} that supports Unix child
|
| -processes on systems which use /proc to control the child.
|
| -
|
| -@item fork-child.c
|
| -This does the low-level grunge that uses Unix system calls to do a ``fork
|
| -and exec'' to start up a child process.
|
| -
|
| -@item infptrace.c
|
| -This is the low level interface to inferior processes for systems using
|
| -the Unix @code{ptrace} call in a vanilla way.
|
| -@end table
|
| -
|
| -@section ptrace
|
| -
|
| -@section /proc
|
| -
|
| -@section win32
|
| -
|
| -@section shared libraries
|
| -
|
| -@section Native Conditionals
|
| -@cindex native conditionals
|
| -
|
| -When @value{GDBN} is configured and compiled, various macros are
|
| -defined or left undefined, to control compilation when the host and
|
| -target systems are the same. These macros should be defined (or left
|
| -undefined) in @file{nm-@var{system}.h}.
|
| -
|
| -@table @code
|
| -
|
| -@item I386_USE_GENERIC_WATCHPOINTS
|
| -An x86-based machine can define this to use the generic x86 watchpoint
|
| -support; see @ref{Algorithms, I386_USE_GENERIC_WATCHPOINTS}.
|
| -
|
| -@item SOLIB_ADD (@var{filename}, @var{from_tty}, @var{targ}, @var{readsyms})
|
| -@findex SOLIB_ADD
|
| -Define this to expand into an expression that will cause the symbols in
|
| -@var{filename} to be added to @value{GDBN}'s symbol table. If
|
| -@var{readsyms} is zero symbols are not read but any necessary low level
|
| -processing for @var{filename} is still done.
|
| -
|
| -@item SOLIB_CREATE_INFERIOR_HOOK
|
| -@findex SOLIB_CREATE_INFERIOR_HOOK
|
| -Define this to expand into any shared-library-relocation code that you
|
| -want to be run just after the child process has been forked.
|
| -
|
| -@item START_INFERIOR_TRAPS_EXPECTED
|
| -@findex START_INFERIOR_TRAPS_EXPECTED
|
| -When starting an inferior, @value{GDBN} normally expects to trap
|
| -twice; once when
|
| -the shell execs, and once when the program itself execs. If the actual
|
| -number of traps is something other than 2, then define this macro to
|
| -expand into the number expected.
|
| -
|
| -@end table
|
| -
|
| -@node Support Libraries
|
| -
|
| -@chapter Support Libraries
|
| -
|
| -@section BFD
|
| -@cindex BFD library
|
| -
|
| -BFD provides support for @value{GDBN} in several ways:
|
| -
|
| -@table @emph
|
| -@item identifying executable and core files
|
| -BFD will identify a variety of file types, including a.out, coff, and
|
| -several variants thereof, as well as several kinds of core files.
|
| -
|
| -@item access to sections of files
|
| -BFD parses the file headers to determine the names, virtual addresses,
|
| -sizes, and file locations of all the various named sections in files
|
| -(such as the text section or the data section). @value{GDBN} simply
|
| -calls BFD to read or write section @var{x} at byte offset @var{y} for
|
| -length @var{z}.
|
| -
|
| -@item specialized core file support
|
| -BFD provides routines to determine the failing command name stored in a
|
| -core file, the signal with which the program failed, and whether a core
|
| -file matches (i.e.@: could be a core dump of) a particular executable
|
| -file.
|
| -
|
| -@item locating the symbol information
|
| -@value{GDBN} uses an internal interface of BFD to determine where to find the
|
| -symbol information in an executable file or symbol-file. @value{GDBN} itself
|
| -handles the reading of symbols, since BFD does not ``understand'' debug
|
| -symbols, but @value{GDBN} uses BFD's cached information to find the symbols,
|
| -string table, etc.
|
| -@end table
|
| -
|
| -@section opcodes
|
| -@cindex opcodes library
|
| -
|
| -The opcodes library provides @value{GDBN}'s disassembler. (It's a separate
|
| -library because it's also used in binutils, for @file{objdump}).
|
| -
|
| -@section readline
|
| -@cindex readline library
|
| -The @code{readline} library provides a set of functions for use by applications
|
| -that allow users to edit command lines as they are typed in.
|
| -
|
| -@section libiberty
|
| -@cindex @code{libiberty} library
|
| -
|
| -The @code{libiberty} library provides a set of functions and features
|
| -that integrate and improve on functionality found in modern operating
|
| -systems. Broadly speaking, such features can be divided into three
|
| -groups: supplemental functions (functions that may be missing in some
|
| -environments and operating systems), replacement functions (providing
|
| -a uniform and easier to use interface for commonly used standard
|
| -functions), and extensions (which provide additional functionality
|
| -beyond standard functions).
|
| -
|
| -@value{GDBN} uses various features provided by the @code{libiberty}
|
| -library, for instance the C@t{++} demangler, the @acronym{IEEE}
|
| -floating format support functions, the input options parser
|
| -@samp{getopt}, the @samp{obstack} extension, and other functions.
|
| -
|
| -@subsection @code{obstacks} in @value{GDBN}
|
| -@cindex @code{obstacks}
|
| -
|
| -The obstack mechanism provides a convenient way to allocate and free
|
| -chunks of memory. Each obstack is a pool of memory that is managed
|
| -like a stack. Objects (of any nature, size and alignment) are
|
| -allocated and freed in a @acronym{LIFO} fashion on an obstack (see
|
| -@code{libiberty}'s documentation for a more detailed explanation of
|
| -@code{obstacks}).
|
| -
|
| -The most noticeable use of the @code{obstacks} in @value{GDBN} is in
|
| -object files. There is an obstack associated with each internal
|
| -representation of an object file. Lots of things get allocated on
|
| -these @code{obstacks}: dictionary entries, blocks, blockvectors,
|
| -symbols, minimal symbols, types, vectors of fundamental types, class
|
| -fields of types, object files section lists, object files section
|
| -offset lists, line tables, symbol tables, partial symbol tables,
|
| -string tables, symbol table private data, macros tables, debug
|
| -information sections and entries, import and export lists (som),
|
| -unwind information (hppa), dwarf2 location expressions data. Plus
|
| -various strings such as directory names strings, debug format strings,
|
| -names of types.
|
| -
|
| -An essential and convenient property of all data on @code{obstacks} is
|
| -that memory for it gets allocated (with @code{obstack_alloc}) at
|
| -various times during a debugging session, but it is released all at
|
| -once using the @code{obstack_free} function. The @code{obstack_free}
|
| -function takes a pointer to where in the stack it must start the
|
| -deletion from (much like the cleanup chains have a pointer to where to
|
| -start the cleanups). Because of the stack like structure of the
|
| -@code{obstacks}, this allows to free only a top portion of the
|
| -obstack. There are a few instances in @value{GDBN} where such thing
|
| -happens. Calls to @code{obstack_free} are done after some local data
|
| -is allocated to the obstack. Only the local data is deleted from the
|
| -obstack. Of course this assumes that nothing between the
|
| -@code{obstack_alloc} and the @code{obstack_free} allocates anything
|
| -else on the same obstack. For this reason it is best and safest to
|
| -use temporary @code{obstacks}.
|
| -
|
| -Releasing the whole obstack is also not safe per se. It is safe only
|
| -under the condition that we know the @code{obstacks} memory is no
|
| -longer needed. In @value{GDBN} we get rid of the @code{obstacks} only
|
| -when we get rid of the whole objfile(s), for instance upon reading a
|
| -new symbol file.
|
| -
|
| -@section gnu-regex
|
| -@cindex regular expressions library
|
| -
|
| -Regex conditionals.
|
| -
|
| -@table @code
|
| -@item C_ALLOCA
|
| -
|
| -@item NFAILURES
|
| -
|
| -@item RE_NREGS
|
| -
|
| -@item SIGN_EXTEND_CHAR
|
| -
|
| -@item SWITCH_ENUM_BUG
|
| -
|
| -@item SYNTAX_TABLE
|
| -
|
| -@item Sword
|
| -
|
| -@item sparc
|
| -@end table
|
| -
|
| -@section Array Containers
|
| -@cindex Array Containers
|
| -@cindex VEC
|
| -
|
| -Often it is necessary to manipulate a dynamic array of a set of
|
| -objects. C forces some bookkeeping on this, which can get cumbersome
|
| -and repetitive. The @file{vec.h} file contains macros for defining
|
| -and using a typesafe vector type. The functions defined will be
|
| -inlined when compiling, and so the abstraction cost should be zero.
|
| -Domain checks are added to detect programming errors.
|
| -
|
| -An example use would be an array of symbols or section information.
|
| -The array can be grown as symbols are read in (or preallocated), and
|
| -the accessor macros provided keep care of all the necessary
|
| -bookkeeping. Because the arrays are type safe, there is no danger of
|
| -accidentally mixing up the contents. Think of these as C++ templates,
|
| -but implemented in C.
|
| -
|
| -Because of the different behavior of structure objects, scalar objects
|
| -and of pointers, there are three flavors of vector, one for each of
|
| -these variants. Both the structure object and pointer variants pass
|
| -pointers to objects around --- in the former case the pointers are
|
| -stored into the vector and in the latter case the pointers are
|
| -dereferenced and the objects copied into the vector. The scalar
|
| -object variant is suitable for @code{int}-like objects, and the vector
|
| -elements are returned by value.
|
| -
|
| -There are both @code{index} and @code{iterate} accessors. The iterator
|
| -returns a boolean iteration condition and updates the iteration
|
| -variable passed by reference. Because the iterator will be inlined,
|
| -the address-of can be optimized away.
|
| -
|
| -The vectors are implemented using the trailing array idiom, thus they
|
| -are not resizeable without changing the address of the vector object
|
| -itself. This means you cannot have variables or fields of vector type
|
| ---- always use a pointer to a vector. The one exception is the final
|
| -field of a structure, which could be a vector type. You will have to
|
| -use the @code{embedded_size} & @code{embedded_init} calls to create
|
| -such objects, and they will probably not be resizeable (so don't use
|
| -the @dfn{safe} allocation variants). The trailing array idiom is used
|
| -(rather than a pointer to an array of data), because, if we allow
|
| -@code{NULL} to also represent an empty vector, empty vectors occupy
|
| -minimal space in the structure containing them.
|
| -
|
| -Each operation that increases the number of active elements is
|
| -available in @dfn{quick} and @dfn{safe} variants. The former presumes
|
| -that there is sufficient allocated space for the operation to succeed
|
| -(it dies if there is not). The latter will reallocate the vector, if
|
| -needed. Reallocation causes an exponential increase in vector size.
|
| -If you know you will be adding N elements, it would be more efficient
|
| -to use the reserve operation before adding the elements with the
|
| -@dfn{quick} operation. This will ensure there are at least as many
|
| -elements as you ask for, it will exponentially increase if there are
|
| -too few spare slots. If you want reserve a specific number of slots,
|
| -but do not want the exponential increase (for instance, you know this
|
| -is the last allocation), use a negative number for reservation. You
|
| -can also create a vector of a specific size from the get go.
|
| -
|
| -You should prefer the push and pop operations, as they append and
|
| -remove from the end of the vector. If you need to remove several items
|
| -in one go, use the truncate operation. The insert and remove
|
| -operations allow you to change elements in the middle of the vector.
|
| -There are two remove operations, one which preserves the element
|
| -ordering @code{ordered_remove}, and one which does not
|
| -@code{unordered_remove}. The latter function copies the end element
|
| -into the removed slot, rather than invoke a memmove operation. The
|
| -@code{lower_bound} function will determine where to place an item in
|
| -the array using insert that will maintain sorted order.
|
| -
|
| -If you need to directly manipulate a vector, then the @code{address}
|
| -accessor will return the address of the start of the vector. Also the
|
| -@code{space} predicate will tell you whether there is spare capacity in the
|
| -vector. You will not normally need to use these two functions.
|
| -
|
| -Vector types are defined using a
|
| -@code{DEF_VEC_@{O,P,I@}(@var{typename})} macro. Variables of vector
|
| -type are declared using a @code{VEC(@var{typename})} macro. The
|
| -characters @code{O}, @code{P} and @code{I} indicate whether
|
| -@var{typename} is an object (@code{O}), pointer (@code{P}) or integral
|
| -(@code{I}) type. Be careful to pick the correct one, as you'll get an
|
| -awkward and inefficient API if you use the wrong one. There is a
|
| -check, which results in a compile-time warning, for the @code{P} and
|
| -@code{I} versions, but there is no check for the @code{O} versions, as
|
| -that is not possible in plain C.
|
| -
|
| -An example of their use would be,
|
| -
|
| -@smallexample
|
| -DEF_VEC_P(tree); // non-managed tree vector.
|
| -
|
| -struct my_struct @{
|
| - VEC(tree) *v; // A (pointer to) a vector of tree pointers.
|
| -@};
|
| -
|
| -struct my_struct *s;
|
| -
|
| -if (VEC_length(tree, s->v)) @{ we have some contents @}
|
| -VEC_safe_push(tree, s->v, decl); // append some decl onto the end
|
| -for (ix = 0; VEC_iterate(tree, s->v, ix, elt); ix++)
|
| - @{ do something with elt @}
|
| -
|
| -@end smallexample
|
| -
|
| -The @file{vec.h} file provides details on how to invoke the various
|
| -accessors provided. They are enumerated here:
|
| -
|
| -@table @code
|
| -@item VEC_length
|
| -Return the number of items in the array,
|
| -
|
| -@item VEC_empty
|
| -Return true if the array has no elements.
|
| -
|
| -@item VEC_last
|
| -@itemx VEC_index
|
| -Return the last or arbitrary item in the array.
|
| -
|
| -@item VEC_iterate
|
| -Access an array element and indicate whether the array has been
|
| -traversed.
|
| -
|
| -@item VEC_alloc
|
| -@itemx VEC_free
|
| -Create and destroy an array.
|
| -
|
| -@item VEC_embedded_size
|
| -@itemx VEC_embedded_init
|
| -Helpers for embedding an array as the final element of another struct.
|
| -
|
| -@item VEC_copy
|
| -Duplicate an array.
|
| -
|
| -@item VEC_space
|
| -Return the amount of free space in an array.
|
| -
|
| -@item VEC_reserve
|
| -Ensure a certain amount of free space.
|
| -
|
| -@item VEC_quick_push
|
| -@itemx VEC_safe_push
|
| -Append to an array, either assuming the space is available, or making
|
| -sure that it is.
|
| -
|
| -@item VEC_pop
|
| -Remove the last item from an array.
|
| -
|
| -@item VEC_truncate
|
| -Remove several items from the end of an array.
|
| -
|
| -@item VEC_safe_grow
|
| -Add several items to the end of an array.
|
| -
|
| -@item VEC_replace
|
| -Overwrite an item in the array.
|
| -
|
| -@item VEC_quick_insert
|
| -@itemx VEC_safe_insert
|
| -Insert an item into the middle of the array. Either the space must
|
| -already exist, or the space is created.
|
| -
|
| -@item VEC_ordered_remove
|
| -@itemx VEC_unordered_remove
|
| -Remove an item from the array, preserving order or not.
|
| -
|
| -@item VEC_block_remove
|
| -Remove a set of items from the array.
|
| -
|
| -@item VEC_address
|
| -Provide the address of the first element.
|
| -
|
| -@item VEC_lower_bound
|
| -Binary search the array.
|
| -
|
| -@end table
|
| -
|
| -@section include
|
| -
|
| -@node Coding Standards
|
| -
|
| -@chapter Coding Standards
|
| -@cindex coding standards
|
| -
|
| -@section @value{GDBN} C Coding Standards
|
| -
|
| -@value{GDBN} follows the GNU coding standards, as described in
|
| -@file{etc/standards.texi}. This file is also available for anonymous
|
| -FTP from GNU archive sites. @value{GDBN} takes a strict interpretation
|
| -of the standard; in general, when the GNU standard recommends a practice
|
| -but does not require it, @value{GDBN} requires it.
|
| -
|
| -@value{GDBN} follows an additional set of coding standards specific to
|
| -@value{GDBN}, as described in the following sections.
|
| -
|
| -@subsection ISO C
|
| -
|
| -@value{GDBN} assumes an ISO/IEC 9899:1990 (a.k.a.@: ISO C90) compliant
|
| -compiler.
|
| -
|
| -@value{GDBN} does not assume an ISO C or POSIX compliant C library.
|
| -
|
| -@subsection Formatting
|
| -
|
| -@cindex source code formatting
|
| -The standard GNU recommendations for formatting must be followed
|
| -strictly. Any @value{GDBN}-specific deviation from GNU
|
| -recomendations is described below.
|
| -
|
| -A function declaration should not have its name in column zero. A
|
| -function definition should have its name in column zero.
|
| -
|
| -@smallexample
|
| -/* Declaration */
|
| -static void foo (void);
|
| -/* Definition */
|
| -void
|
| -foo (void)
|
| -@{
|
| -@}
|
| -@end smallexample
|
| -
|
| -@emph{Pragmatics: This simplifies scripting. Function definitions can
|
| -be found using @samp{^function-name}.}
|
| -
|
| -There must be a space between a function or macro name and the opening
|
| -parenthesis of its argument list (except for macro definitions, as
|
| -required by C). There must not be a space after an open paren/bracket
|
| -or before a close paren/bracket.
|
| -
|
| -While additional whitespace is generally helpful for reading, do not use
|
| -more than one blank line to separate blocks, and avoid adding whitespace
|
| -after the end of a program line (as of 1/99, some 600 lines had
|
| -whitespace after the semicolon). Excess whitespace causes difficulties
|
| -for @code{diff} and @code{patch} utilities.
|
| -
|
| -Pointers are declared using the traditional K&R C style:
|
| -
|
| -@smallexample
|
| -void *foo;
|
| -@end smallexample
|
| -
|
| -@noindent
|
| -and not:
|
| -
|
| -@smallexample
|
| -void * foo;
|
| -void* foo;
|
| -@end smallexample
|
| -
|
| -In addition, whitespace around casts and unary operators should follow
|
| -the following guidelines:
|
| -
|
| -@multitable @columnfractions .2 .2 .8
|
| -@item Use... @tab ...instead of @tab
|
| -
|
| -@item @code{!x}
|
| -@tab @code{! x}
|
| -@item @code{~x}
|
| -@tab @code{~ x}
|
| -@item @code{-x}
|
| -@tab @code{- x}
|
| -@tab (unary minus)
|
| -@item @code{(foo) x}
|
| -@tab @code{(foo)x}
|
| -@tab (cast)
|
| -@item @code{*x}
|
| -@tab @code{* x}
|
| -@tab (pointer dereference)
|
| -@end multitable
|
| -
|
| -Any two or more lines in code should be wrapped in braces, even if
|
| -they are comments, as they look like separate statements:
|
| -
|
| -@smallexample
|
| -if (i)
|
| - @{
|
| - /* Return success. */
|
| - return 0;
|
| - @}
|
| -@end smallexample
|
| -
|
| -@noindent
|
| -and not:
|
| -
|
| -@smallexample
|
| -if (i)
|
| - /* Return success. */
|
| - return 0;
|
| -@end smallexample
|
| -
|
| -@subsection Comments
|
| -
|
| -@cindex comment formatting
|
| -The standard GNU requirements on comments must be followed strictly.
|
| -
|
| -Block comments must appear in the following form, with no @code{/*}- or
|
| -@code{*/}-only lines, and no leading @code{*}:
|
| -
|
| -@smallexample
|
| -/* Wait for control to return from inferior to debugger. If inferior
|
| - gets a signal, we may decide to start it up again instead of
|
| - returning. That is why there is a loop in this function. When
|
| - this function actually returns it means the inferior should be left
|
| - stopped and @value{GDBN} should read more commands. */
|
| -@end smallexample
|
| -
|
| -(Note that this format is encouraged by Emacs; tabbing for a multi-line
|
| -comment works correctly, and @kbd{M-q} fills the block consistently.)
|
| -
|
| -Put a blank line between the block comments preceding function or
|
| -variable definitions, and the definition itself.
|
| -
|
| -In general, put function-body comments on lines by themselves, rather
|
| -than trying to fit them into the 20 characters left at the end of a
|
| -line, since either the comment or the code will inevitably get longer
|
| -than will fit, and then somebody will have to move it anyhow.
|
| -
|
| -@subsection C Usage
|
| -
|
| -@cindex C data types
|
| -Code must not depend on the sizes of C data types, the format of the
|
| -host's floating point numbers, the alignment of anything, or the order
|
| -of evaluation of expressions.
|
| -
|
| -@cindex function usage
|
| -Use functions freely. There are only a handful of compute-bound areas
|
| -in @value{GDBN} that might be affected by the overhead of a function
|
| -call, mainly in symbol reading. Most of @value{GDBN}'s performance is
|
| -limited by the target interface (whether serial line or system call).
|
| -
|
| -However, use functions with moderation. A thousand one-line functions
|
| -are just as hard to understand as a single thousand-line function.
|
| -
|
| -@emph{Macros are bad, M'kay.}
|
| -(But if you have to use a macro, make sure that the macro arguments are
|
| -protected with parentheses.)
|
| -
|
| -@cindex types
|
| -
|
| -Declarations like @samp{struct foo *} should be used in preference to
|
| -declarations like @samp{typedef struct foo @{ @dots{} @} *foo_ptr}.
|
| -
|
| -@subsection Function Prototypes
|
| -@cindex function prototypes
|
| -
|
| -Prototypes must be used when both @emph{declaring} and @emph{defining}
|
| -a function. Prototypes for @value{GDBN} functions must include both the
|
| -argument type and name, with the name matching that used in the actual
|
| -function definition.
|
| -
|
| -All external functions should have a declaration in a header file that
|
| -callers include, except for @code{_initialize_*} functions, which must
|
| -be external so that @file{init.c} construction works, but shouldn't be
|
| -visible to random source files.
|
| -
|
| -Where a source file needs a forward declaration of a static function,
|
| -that declaration must appear in a block near the top of the source file.
|
| -
|
| -@subsection File Names
|
| -
|
| -Any file used when building the core of @value{GDBN} must be in lower
|
| -case. Any file used when building the core of @value{GDBN} must be 8.3
|
| -unique. These requirements apply to both source and generated files.
|
| -
|
| -@emph{Pragmatics: The core of @value{GDBN} must be buildable on many
|
| -platforms including DJGPP and MacOS/HFS. Every time an unfriendly file
|
| -is introduced to the build process both @file{Makefile.in} and
|
| -@file{configure.in} need to be modified accordingly. Compare the
|
| -convoluted conversion process needed to transform @file{COPYING} into
|
| -@file{copying.c} with the conversion needed to transform
|
| -@file{version.in} into @file{version.c}.}
|
| -
|
| -Any file non 8.3 compliant file (that is not used when building the core
|
| -of @value{GDBN}) must be added to @file{gdb/config/djgpp/fnchange.lst}.
|
| -
|
| -@emph{Pragmatics: This is clearly a compromise.}
|
| -
|
| -When @value{GDBN} has a local version of a system header file (ex
|
| -@file{string.h}) the file name based on the POSIX header prefixed with
|
| -@file{gdb_} (@file{gdb_string.h}). These headers should be relatively
|
| -independent: they should use only macros defined by @file{configure},
|
| -the compiler, or the host; they should include only system headers; they
|
| -should refer only to system types. They may be shared between multiple
|
| -programs, e.g.@: @value{GDBN} and @sc{gdbserver}.
|
| -
|
| -For other files @samp{-} is used as the separator.
|
| -
|
| -@subsection Include Files
|
| -
|
| -A @file{.c} file should include @file{defs.h} first.
|
| -
|
| -A @file{.c} file should directly include the @code{.h} file of every
|
| -declaration and/or definition it directly refers to. It cannot rely on
|
| -indirect inclusion.
|
| -
|
| -A @file{.h} file should directly include the @code{.h} file of every
|
| -declaration and/or definition it directly refers to. It cannot rely on
|
| -indirect inclusion. Exception: The file @file{defs.h} does not need to
|
| -be directly included.
|
| -
|
| -An external declaration should only appear in one include file.
|
| -
|
| -An external declaration should never appear in a @code{.c} file.
|
| -Exception: a declaration for the @code{_initialize} function that
|
| -pacifies @option{-Wmissing-declaration}.
|
| -
|
| -A @code{typedef} definition should only appear in one include file.
|
| -
|
| -An opaque @code{struct} declaration can appear in multiple @file{.h}
|
| -files. Where possible, a @file{.h} file should use an opaque
|
| -@code{struct} declaration instead of an include.
|
| -
|
| -All @file{.h} files should be wrapped in:
|
| -
|
| -@smallexample
|
| -#ifndef INCLUDE_FILE_NAME_H
|
| -#define INCLUDE_FILE_NAME_H
|
| -header body
|
| -#endif
|
| -@end smallexample
|
| -
|
| -@section @value{GDBN} Python Coding Standards
|
| -
|
| -@value{GDBN} follows the published @code{Python} coding standards in
|
| -@uref{http://www.python.org/dev/peps/pep-0008/, @code{PEP008}}.
|
| -
|
| -In addition, the guidelines in the
|
| -@uref{http://google-styleguide.googlecode.com/svn/trunk/pyguide.html,
|
| -Google Python Style Guide} are also followed where they do not
|
| -conflict with @code{PEP008}.
|
| -
|
| -@subsection @value{GDBN}-specific exceptions
|
| -
|
| -There are a few exceptions to the published standards.
|
| -They exist mainly for consistency with the @code{C} standards.
|
| -
|
| -@c It is expected that there are a few more exceptions,
|
| -@c so we use itemize here.
|
| -
|
| -@itemize @bullet
|
| -
|
| -@item
|
| -Use @code{FIXME} instead of @code{TODO}.
|
| -
|
| -@end itemize
|
| -
|
| -@node Misc Guidelines
|
| -
|
| -@chapter Misc Guidelines
|
| -
|
| -This chapter covers topics that are lower-level than the major
|
| -algorithms of @value{GDBN}.
|
| -
|
| -@section Cleanups
|
| -@cindex cleanups
|
| -
|
| -Cleanups are a structured way to deal with things that need to be done
|
| -later.
|
| -
|
| -When your code does something (e.g., @code{xmalloc} some memory, or
|
| -@code{open} a file) that needs to be undone later (e.g., @code{xfree}
|
| -the memory or @code{close} the file), it can make a cleanup. The
|
| -cleanup will be done at some future point: when the command is finished
|
| -and control returns to the top level; when an error occurs and the stack
|
| -is unwound; or when your code decides it's time to explicitly perform
|
| -cleanups. Alternatively you can elect to discard the cleanups you
|
| -created.
|
| -
|
| -Syntax:
|
| -
|
| -@table @code
|
| -@item struct cleanup *@var{old_chain};
|
| -Declare a variable which will hold a cleanup chain handle.
|
| -
|
| -@findex make_cleanup
|
| -@item @var{old_chain} = make_cleanup (@var{function}, @var{arg});
|
| -Make a cleanup which will cause @var{function} to be called with
|
| -@var{arg} (a @code{char *}) later. The result, @var{old_chain}, is a
|
| -handle that can later be passed to @code{do_cleanups} or
|
| -@code{discard_cleanups}. Unless you are going to call
|
| -@code{do_cleanups} or @code{discard_cleanups}, you can ignore the result
|
| -from @code{make_cleanup}.
|
| -
|
| -@findex do_cleanups
|
| -@item do_cleanups (@var{old_chain});
|
| -Do all cleanups added to the chain since the corresponding
|
| -@code{make_cleanup} call was made.
|
| -
|
| -@findex discard_cleanups
|
| -@item discard_cleanups (@var{old_chain});
|
| -Same as @code{do_cleanups} except that it just removes the cleanups from
|
| -the chain and does not call the specified functions.
|
| -@end table
|
| -
|
| -Cleanups are implemented as a chain. The handle returned by
|
| -@code{make_cleanups} includes the cleanup passed to the call and any
|
| -later cleanups appended to the chain (but not yet discarded or
|
| -performed). E.g.:
|
| -
|
| -@smallexample
|
| -make_cleanup (a, 0);
|
| -@{
|
| - struct cleanup *old = make_cleanup (b, 0);
|
| - make_cleanup (c, 0)
|
| - ...
|
| - do_cleanups (old);
|
| -@}
|
| -@end smallexample
|
| -
|
| -@noindent
|
| -will call @code{c()} and @code{b()} but will not call @code{a()}. The
|
| -cleanup that calls @code{a()} will remain in the cleanup chain, and will
|
| -be done later unless otherwise discarded.@refill
|
| -
|
| -Your function should explicitly do or discard the cleanups it creates.
|
| -Failing to do this leads to non-deterministic behavior since the caller
|
| -will arbitrarily do or discard your functions cleanups. This need leads
|
| -to two common cleanup styles.
|
| -
|
| -The first style is try/finally. Before it exits, your code-block calls
|
| -@code{do_cleanups} with the old cleanup chain and thus ensures that your
|
| -code-block's cleanups are always performed. For instance, the following
|
| -code-segment avoids a memory leak problem (even when @code{error} is
|
| -called and a forced stack unwind occurs) by ensuring that the
|
| -@code{xfree} will always be called:
|
| -
|
| -@smallexample
|
| -struct cleanup *old = make_cleanup (null_cleanup, 0);
|
| -data = xmalloc (sizeof blah);
|
| -make_cleanup (xfree, data);
|
| -... blah blah ...
|
| -do_cleanups (old);
|
| -@end smallexample
|
| -
|
| -The second style is try/except. Before it exits, your code-block calls
|
| -@code{discard_cleanups} with the old cleanup chain and thus ensures that
|
| -any created cleanups are not performed. For instance, the following
|
| -code segment, ensures that the file will be closed but only if there is
|
| -an error:
|
| -
|
| -@smallexample
|
| -FILE *file = fopen ("afile", "r");
|
| -struct cleanup *old = make_cleanup (close_file, file);
|
| -... blah blah ...
|
| -discard_cleanups (old);
|
| -return file;
|
| -@end smallexample
|
| -
|
| -Some functions, e.g., @code{fputs_filtered()} or @code{error()}, specify
|
| -that they ``should not be called when cleanups are not in place''. This
|
| -means that any actions you need to reverse in the case of an error or
|
| -interruption must be on the cleanup chain before you call these
|
| -functions, since they might never return to your code (they
|
| -@samp{longjmp} instead).
|
| -
|
| -@section Per-architecture module data
|
| -@cindex per-architecture module data
|
| -@cindex multi-arch data
|
| -@cindex data-pointer, per-architecture/per-module
|
| -
|
| -The multi-arch framework includes a mechanism for adding module
|
| -specific per-architecture data-pointers to the @code{struct gdbarch}
|
| -architecture object.
|
| -
|
| -A module registers one or more per-architecture data-pointers using:
|
| -
|
| -@deftypefn {Architecture Function} {struct gdbarch_data *} gdbarch_data_register_pre_init (gdbarch_data_pre_init_ftype *@var{pre_init})
|
| -@var{pre_init} is used to, on-demand, allocate an initial value for a
|
| -per-architecture data-pointer using the architecture's obstack (passed
|
| -in as a parameter). Since @var{pre_init} can be called during
|
| -architecture creation, it is not parameterized with the architecture.
|
| -and must not call modules that use per-architecture data.
|
| -@end deftypefn
|
| -
|
| -@deftypefn {Architecture Function} {struct gdbarch_data *} gdbarch_data_register_post_init (gdbarch_data_post_init_ftype *@var{post_init})
|
| -@var{post_init} is used to obtain an initial value for a
|
| -per-architecture data-pointer @emph{after}. Since @var{post_init} is
|
| -always called after architecture creation, it both receives the fully
|
| -initialized architecture and is free to call modules that use
|
| -per-architecture data (care needs to be taken to ensure that those
|
| -other modules do not try to call back to this module as that will
|
| -create in cycles in the initialization call graph).
|
| -@end deftypefn
|
| -
|
| -These functions return a @code{struct gdbarch_data} that is used to
|
| -identify the per-architecture data-pointer added for that module.
|
| -
|
| -The per-architecture data-pointer is accessed using the function:
|
| -
|
| -@deftypefn {Architecture Function} {void *} gdbarch_data (struct gdbarch *@var{gdbarch}, struct gdbarch_data *@var{data_handle})
|
| -Given the architecture @var{arch} and module data handle
|
| -@var{data_handle} (returned by @code{gdbarch_data_register_pre_init}
|
| -or @code{gdbarch_data_register_post_init}), this function returns the
|
| -current value of the per-architecture data-pointer. If the data
|
| -pointer is @code{NULL}, it is first initialized by calling the
|
| -corresponding @var{pre_init} or @var{post_init} method.
|
| -@end deftypefn
|
| -
|
| -The examples below assume the following definitions:
|
| -
|
| -@smallexample
|
| -struct nozel @{ int total; @};
|
| -static struct gdbarch_data *nozel_handle;
|
| -@end smallexample
|
| -
|
| -A module can extend the architecture vector, adding additional
|
| -per-architecture data, using the @var{pre_init} method. The module's
|
| -per-architecture data is then initialized during architecture
|
| -creation.
|
| -
|
| -In the below, the module's per-architecture @emph{nozel} is added. An
|
| -architecture can specify its nozel by calling @code{set_gdbarch_nozel}
|
| -from @code{gdbarch_init}.
|
| -
|
| -@smallexample
|
| -static void *
|
| -nozel_pre_init (struct obstack *obstack)
|
| -@{
|
| - struct nozel *data = OBSTACK_ZALLOC (obstack, struct nozel);
|
| - return data;
|
| -@}
|
| -@end smallexample
|
| -
|
| -@smallexample
|
| -extern void
|
| -set_gdbarch_nozel (struct gdbarch *gdbarch, int total)
|
| -@{
|
| - struct nozel *data = gdbarch_data (gdbarch, nozel_handle);
|
| - data->total = nozel;
|
| -@}
|
| -@end smallexample
|
| -
|
| -A module can on-demand create architecture dependent data structures
|
| -using @code{post_init}.
|
| -
|
| -In the below, the nozel's total is computed on-demand by
|
| -@code{nozel_post_init} using information obtained from the
|
| -architecture.
|
| -
|
| -@smallexample
|
| -static void *
|
| -nozel_post_init (struct gdbarch *gdbarch)
|
| -@{
|
| - struct nozel *data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct nozel);
|
| - nozel->total = gdbarch@dots{} (gdbarch);
|
| - return data;
|
| -@}
|
| -@end smallexample
|
| -
|
| -@smallexample
|
| -extern int
|
| -nozel_total (struct gdbarch *gdbarch)
|
| -@{
|
| - struct nozel *data = gdbarch_data (gdbarch, nozel_handle);
|
| - return data->total;
|
| -@}
|
| -@end smallexample
|
| -
|
| -@section Wrapping Output Lines
|
| -@cindex line wrap in output
|
| -
|
| -@findex wrap_here
|
| -Output that goes through @code{printf_filtered} or @code{fputs_filtered}
|
| -or @code{fputs_demangled} needs only to have calls to @code{wrap_here}
|
| -added in places that would be good breaking points. The utility
|
| -routines will take care of actually wrapping if the line width is
|
| -exceeded.
|
| -
|
| -The argument to @code{wrap_here} is an indentation string which is
|
| -printed @emph{only} if the line breaks there. This argument is saved
|
| -away and used later. It must remain valid until the next call to
|
| -@code{wrap_here} or until a newline has been printed through the
|
| -@code{*_filtered} functions. Don't pass in a local variable and then
|
| -return!
|
| -
|
| -It is usually best to call @code{wrap_here} after printing a comma or
|
| -space. If you call it before printing a space, make sure that your
|
| -indentation properly accounts for the leading space that will print if
|
| -the line wraps there.
|
| -
|
| -Any function or set of functions that produce filtered output must
|
| -finish by printing a newline, to flush the wrap buffer, before switching
|
| -to unfiltered (@code{printf}) output. Symbol reading routines that
|
| -print warnings are a good example.
|
| -
|
| -@section Memory Management
|
| -
|
| -@value{GDBN} does not use the functions @code{malloc}, @code{realloc},
|
| -@code{calloc}, @code{free} and @code{asprintf}.
|
| -
|
| -@value{GDBN} uses the functions @code{xmalloc}, @code{xrealloc} and
|
| -@code{xcalloc} when allocating memory. Unlike @code{malloc} et.al.@:
|
| -these functions do not return when the memory pool is empty. Instead,
|
| -they unwind the stack using cleanups. These functions return
|
| -@code{NULL} when requested to allocate a chunk of memory of size zero.
|
| -
|
| -@emph{Pragmatics: By using these functions, the need to check every
|
| -memory allocation is removed. These functions provide portable
|
| -behavior.}
|
| -
|
| -@value{GDBN} does not use the function @code{free}.
|
| -
|
| -@value{GDBN} uses the function @code{xfree} to return memory to the
|
| -memory pool. Consistent with ISO-C, this function ignores a request to
|
| -free a @code{NULL} pointer.
|
| -
|
| -@emph{Pragmatics: On some systems @code{free} fails when passed a
|
| -@code{NULL} pointer.}
|
| -
|
| -@value{GDBN} can use the non-portable function @code{alloca} for the
|
| -allocation of small temporary values (such as strings).
|
| -
|
| -@emph{Pragmatics: This function is very non-portable. Some systems
|
| -restrict the memory being allocated to no more than a few kilobytes.}
|
| -
|
| -@value{GDBN} uses the string function @code{xstrdup} and the print
|
| -function @code{xstrprintf}.
|
| -
|
| -@emph{Pragmatics: @code{asprintf} and @code{strdup} can fail. Print
|
| -functions such as @code{sprintf} are very prone to buffer overflow
|
| -errors.}
|
| -
|
| -
|
| -@section Compiler Warnings
|
| -@cindex compiler warnings
|
| -
|
| -With few exceptions, developers should avoid the configuration option
|
| -@samp{--disable-werror} when building @value{GDBN}. The exceptions
|
| -are listed in the file @file{gdb/MAINTAINERS}. The default, when
|
| -building with @sc{gcc}, is @samp{--enable-werror}.
|
| -
|
| -This option causes @value{GDBN} (when built using GCC) to be compiled
|
| -with a carefully selected list of compiler warning flags. Any warnings
|
| -from those flags are treated as errors.
|
| -
|
| -The current list of warning flags includes:
|
| -
|
| -@table @samp
|
| -@item -Wall
|
| -Recommended @sc{gcc} warnings.
|
| -
|
| -@item -Wdeclaration-after-statement
|
| -
|
| -@sc{gcc} 3.x (and later) and @sc{c99} allow declarations mixed with
|
| -code, but @sc{gcc} 2.x and @sc{c89} do not.
|
| -
|
| -@item -Wpointer-arith
|
| -
|
| -@item -Wformat-nonliteral
|
| -Non-literal format strings, with a few exceptions, are bugs - they
|
| -might contain unintended user-supplied format specifiers.
|
| -Since @value{GDBN} uses the @code{format printf} attribute on all
|
| -@code{printf} like functions this checks not just @code{printf} calls
|
| -but also calls to functions such as @code{fprintf_unfiltered}.
|
| -
|
| -@item -Wno-pointer-sign
|
| -In version 4.0, GCC began warning about pointer argument passing or
|
| -assignment even when the source and destination differed only in
|
| -signedness. However, most @value{GDBN} code doesn't distinguish
|
| -carefully between @code{char} and @code{unsigned char}. In early 2006
|
| -the @value{GDBN} developers decided correcting these warnings wasn't
|
| -worth the time it would take.
|
| -
|
| -@item -Wno-unused-parameter
|
| -Due to the way that @value{GDBN} is implemented many functions have
|
| -unused parameters. Consequently this warning is avoided. The macro
|
| -@code{ATTRIBUTE_UNUSED} is not used as it leads to false negatives ---
|
| -it is not an error to have @code{ATTRIBUTE_UNUSED} on a parameter that
|
| -is being used.
|
| -
|
| -@item -Wno-unused
|
| -@itemx -Wno-switch
|
| -@itemx -Wno-char-subscripts
|
| -These are warnings which might be useful for @value{GDBN}, but are
|
| -currently too noisy to enable with @samp{-Werror}.
|
| -
|
| -@end table
|
| -
|
| -@section Internal Error Recovery
|
| -
|
| -During its execution, @value{GDBN} can encounter two types of errors.
|
| -User errors and internal errors. User errors include not only a user
|
| -entering an incorrect command but also problems arising from corrupt
|
| -object files and system errors when interacting with the target.
|
| -Internal errors include situations where @value{GDBN} has detected, at
|
| -run time, a corrupt or erroneous situation.
|
| -
|
| -When reporting an internal error, @value{GDBN} uses
|
| -@code{internal_error} and @code{gdb_assert}.
|
| -
|
| -@value{GDBN} must not call @code{abort} or @code{assert}.
|
| -
|
| -@emph{Pragmatics: There is no @code{internal_warning} function. Either
|
| -the code detected a user error, recovered from it and issued a
|
| -@code{warning} or the code failed to correctly recover from the user
|
| -error and issued an @code{internal_error}.}
|
| -
|
| -@section Command Names
|
| -
|
| -GDB U/I commands are written @samp{foo-bar}, not @samp{foo_bar}.
|
| -
|
| -@section Clean Design and Portable Implementation
|
| -
|
| -@cindex design
|
| -In addition to getting the syntax right, there's the little question of
|
| -semantics. Some things are done in certain ways in @value{GDBN} because long
|
| -experience has shown that the more obvious ways caused various kinds of
|
| -trouble.
|
| -
|
| -@cindex assumptions about targets
|
| -You can't assume the byte order of anything that comes from a target
|
| -(including @var{value}s, object files, and instructions). Such things
|
| -must be byte-swapped using @code{SWAP_TARGET_AND_HOST} in
|
| -@value{GDBN}, or one of the swap routines defined in @file{bfd.h},
|
| -such as @code{bfd_get_32}.
|
| -
|
| -You can't assume that you know what interface is being used to talk to
|
| -the target system. All references to the target must go through the
|
| -current @code{target_ops} vector.
|
| -
|
| -You can't assume that the host and target machines are the same machine
|
| -(except in the ``native'' support modules). In particular, you can't
|
| -assume that the target machine's header files will be available on the
|
| -host machine. Target code must bring along its own header files --
|
| -written from scratch or explicitly donated by their owner, to avoid
|
| -copyright problems.
|
| -
|
| -@cindex portability
|
| -Insertion of new @code{#ifdef}'s will be frowned upon. It's much better
|
| -to write the code portably than to conditionalize it for various
|
| -systems.
|
| -
|
| -@cindex system dependencies
|
| -New @code{#ifdef}'s which test for specific compilers or manufacturers
|
| -or operating systems are unacceptable. All @code{#ifdef}'s should test
|
| -for features. The information about which configurations contain which
|
| -features should be segregated into the configuration files. Experience
|
| -has proven far too often that a feature unique to one particular system
|
| -often creeps into other systems; and that a conditional based on some
|
| -predefined macro for your current system will become worthless over
|
| -time, as new versions of your system come out that behave differently
|
| -with regard to this feature.
|
| -
|
| -Adding code that handles specific architectures, operating systems,
|
| -target interfaces, or hosts, is not acceptable in generic code.
|
| -
|
| -@cindex portable file name handling
|
| -@cindex file names, portability
|
| -One particularly notorious area where system dependencies tend to
|
| -creep in is handling of file names. The mainline @value{GDBN} code
|
| -assumes Posix semantics of file names: absolute file names begin with
|
| -a forward slash @file{/}, slashes are used to separate leading
|
| -directories, case-sensitive file names. These assumptions are not
|
| -necessarily true on non-Posix systems such as MS-Windows. To avoid
|
| -system-dependent code where you need to take apart or construct a file
|
| -name, use the following portable macros:
|
| -
|
| -@table @code
|
| -@findex HAVE_DOS_BASED_FILE_SYSTEM
|
| -@item HAVE_DOS_BASED_FILE_SYSTEM
|
| -This preprocessing symbol is defined to a non-zero value on hosts
|
| -whose filesystems belong to the MS-DOS/MS-Windows family. Use this
|
| -symbol to write conditional code which should only be compiled for
|
| -such hosts.
|
| -
|
| -@findex IS_DIR_SEPARATOR
|
| -@item IS_DIR_SEPARATOR (@var{c})
|
| -Evaluates to a non-zero value if @var{c} is a directory separator
|
| -character. On Unix and GNU/Linux systems, only a slash @file{/} is
|
| -such a character, but on Windows, both @file{/} and @file{\} will
|
| -pass.
|
| -
|
| -@findex IS_ABSOLUTE_PATH
|
| -@item IS_ABSOLUTE_PATH (@var{file})
|
| -Evaluates to a non-zero value if @var{file} is an absolute file name.
|
| -For Unix and GNU/Linux hosts, a name which begins with a slash
|
| -@file{/} is absolute. On DOS and Windows, @file{d:/foo} and
|
| -@file{x:\bar} are also absolute file names.
|
| -
|
| -@findex FILENAME_CMP
|
| -@item FILENAME_CMP (@var{f1}, @var{f2})
|
| -Calls a function which compares file names @var{f1} and @var{f2} as
|
| -appropriate for the underlying host filesystem. For Posix systems,
|
| -this simply calls @code{strcmp}; on case-insensitive filesystems it
|
| -will call @code{strcasecmp} instead.
|
| -
|
| -@findex DIRNAME_SEPARATOR
|
| -@item DIRNAME_SEPARATOR
|
| -Evaluates to a character which separates directories in
|
| -@code{PATH}-style lists, typically held in environment variables.
|
| -This character is @samp{:} on Unix, @samp{;} on DOS and Windows.
|
| -
|
| -@findex SLASH_STRING
|
| -@item SLASH_STRING
|
| -This evaluates to a constant string you should use to produce an
|
| -absolute filename from leading directories and the file's basename.
|
| -@code{SLASH_STRING} is @code{"/"} on most systems, but might be
|
| -@code{"\\"} for some Windows-based ports.
|
| -@end table
|
| -
|
| -In addition to using these macros, be sure to use portable library
|
| -functions whenever possible. For example, to extract a directory or a
|
| -basename part from a file name, use the @code{dirname} and
|
| -@code{basename} library functions (available in @code{libiberty} for
|
| -platforms which don't provide them), instead of searching for a slash
|
| -with @code{strrchr}.
|
| -
|
| -Another way to generalize @value{GDBN} along a particular interface is with an
|
| -attribute struct. For example, @value{GDBN} has been generalized to handle
|
| -multiple kinds of remote interfaces---not by @code{#ifdef}s everywhere, but
|
| -by defining the @code{target_ops} structure and having a current target (as
|
| -well as a stack of targets below it, for memory references). Whenever
|
| -something needs to be done that depends on which remote interface we are
|
| -using, a flag in the current target_ops structure is tested (e.g.,
|
| -@code{target_has_stack}), or a function is called through a pointer in the
|
| -current target_ops structure. In this way, when a new remote interface
|
| -is added, only one module needs to be touched---the one that actually
|
| -implements the new remote interface. Other examples of
|
| -attribute-structs are BFD access to multiple kinds of object file
|
| -formats, or @value{GDBN}'s access to multiple source languages.
|
| -
|
| -Please avoid duplicating code. For example, in @value{GDBN} 3.x all
|
| -the code interfacing between @code{ptrace} and the rest of
|
| -@value{GDBN} was duplicated in @file{*-dep.c}, and so changing
|
| -something was very painful. In @value{GDBN} 4.x, these have all been
|
| -consolidated into @file{infptrace.c}. @file{infptrace.c} can deal
|
| -with variations between systems the same way any system-independent
|
| -file would (hooks, @code{#if defined}, etc.), and machines which are
|
| -radically different don't need to use @file{infptrace.c} at all.
|
| -
|
| -All debugging code must be controllable using the @samp{set debug
|
| -@var{module}} command. Do not use @code{printf} to print trace
|
| -messages. Use @code{fprintf_unfiltered(gdb_stdlog, ...}. Do not use
|
| -@code{#ifdef DEBUG}.
|
| -
|
| -@node Porting GDB
|
| -
|
| -@chapter Porting @value{GDBN}
|
| -@cindex porting to new machines
|
| -
|
| -Most of the work in making @value{GDBN} compile on a new machine is in
|
| -specifying the configuration of the machine. Porting a new
|
| -architecture to @value{GDBN} can be broken into a number of steps.
|
| -
|
| -@itemize @bullet
|
| -
|
| -@item
|
| -Ensure a @sc{bfd} exists for executables of the target architecture in
|
| -the @file{bfd} directory. If one does not exist, create one by
|
| -modifying an existing similar one.
|
| -
|
| -@item
|
| -Implement a disassembler for the target architecture in the @file{opcodes}
|
| -directory.
|
| -
|
| -@item
|
| -Define the target architecture in the @file{gdb} directory
|
| -(@pxref{Adding a New Target, , Adding a New Target}). Add the pattern
|
| -for the new target to @file{configure.tgt} with the names of the files
|
| -that contain the code. By convention the target architecture
|
| -definition for an architecture @var{arch} is placed in
|
| -@file{@var{arch}-tdep.c}.
|
| -
|
| -Within @file{@var{arch}-tdep.c} define the function
|
| -@code{_initialize_@var{arch}_tdep} which calls
|
| -@code{gdbarch_register} to create the new @code{@w{struct
|
| -gdbarch}} for the architecture.
|
| -
|
| -@item
|
| -If a new remote target is needed, consider adding a new remote target
|
| -by defining a function
|
| -@code{_initialize_remote_@var{arch}}. However if at all possible
|
| -use the @value{GDBN} @emph{Remote Serial Protocol} for this and implement
|
| -the server side protocol independently with the target.
|
| -
|
| -@item
|
| -If desired implement a simulator in the @file{sim} directory. This
|
| -should create the library @file{libsim.a} implementing the interface
|
| -in @file{remote-sim.h} (found in the @file{include} directory).
|
| -
|
| -@item
|
| -Build and test. If desired, lobby the @sc{gdb} steering group to
|
| -have the new port included in the main distribution!
|
| -
|
| -@item
|
| -Add a description of the new architecture to the main @value{GDBN} user
|
| -guide (@pxref{Configuration Specific Information, , Configuration
|
| -Specific Information, gdb, Debugging with @value{GDBN}}).
|
| -
|
| -@end itemize
|
| -
|
| -@node Versions and Branches
|
| -@chapter Versions and Branches
|
| -
|
| -@section Versions
|
| -
|
| -@value{GDBN}'s version is determined by the file
|
| -@file{gdb/version.in} and takes one of the following forms:
|
| -
|
| -@table @asis
|
| -@item @var{major}.@var{minor}
|
| -@itemx @var{major}.@var{minor}.@var{patchlevel}
|
| -an official release (e.g., 6.2 or 6.2.1)
|
| -@item @var{major}.@var{minor}.@var{patchlevel}.@var{YYYY}@var{MM}@var{DD}
|
| -a snapshot taken at @var{YYYY}-@var{MM}-@var{DD}-gmt (e.g.,
|
| -6.1.50.20020302, 6.1.90.20020304, or 6.1.0.20020308)
|
| -@item @var{major}.@var{minor}.@var{patchlevel}.@var{YYYY}@var{MM}@var{DD}-cvs
|
| -a @sc{cvs} check out drawn on @var{YYYY}-@var{MM}-@var{DD} (e.g.,
|
| -6.1.50.20020302-cvs, 6.1.90.20020304-cvs, or 6.1.0.20020308-cvs)
|
| -@item @var{major}.@var{minor}.@var{patchlevel}.@var{YYYY}@var{MM}@var{DD} (@var{vendor})
|
| -a vendor specific release of @value{GDBN}, that while based on@*
|
| -@var{major}.@var{minor}.@var{patchlevel}.@var{YYYY}@var{MM}@var{DD},
|
| -may include additional changes
|
| -@end table
|
| -
|
| -@value{GDBN}'s mainline uses the @var{major} and @var{minor} version
|
| -numbers from the most recent release branch, with a @var{patchlevel}
|
| -of 50. At the time each new release branch is created, the mainline's
|
| -@var{major} and @var{minor} version numbers are updated.
|
| -
|
| -@value{GDBN}'s release branch is similar. When the branch is cut, the
|
| -@var{patchlevel} is changed from 50 to 90. As draft releases are
|
| -drawn from the branch, the @var{patchlevel} is incremented. Once the
|
| -first release (@var{major}.@var{minor}) has been made, the
|
| -@var{patchlevel} is set to 0 and updates have an incremented
|
| -@var{patchlevel}.
|
| -
|
| -For snapshots, and @sc{cvs} check outs, it is also possible to
|
| -identify the @sc{cvs} origin:
|
| -
|
| -@table @asis
|
| -@item @var{major}.@var{minor}.50.@var{YYYY}@var{MM}@var{DD}
|
| -drawn from the @sc{head} of mainline @sc{cvs} (e.g., 6.1.50.20020302)
|
| -@item @var{major}.@var{minor}.90.@var{YYYY}@var{MM}@var{DD}
|
| -@itemx @var{major}.@var{minor}.91.@var{YYYY}@var{MM}@var{DD} @dots{}
|
| -drawn from a release branch prior to the release (e.g.,
|
| -6.1.90.20020304)
|
| -@item @var{major}.@var{minor}.0.@var{YYYY}@var{MM}@var{DD}
|
| -@itemx @var{major}.@var{minor}.1.@var{YYYY}@var{MM}@var{DD} @dots{}
|
| -drawn from a release branch after the release (e.g., 6.2.0.20020308)
|
| -@end table
|
| -
|
| -If the previous @value{GDBN} version is 6.1 and the current version is
|
| -6.2, then, substituting 6 for @var{major} and 1 or 2 for @var{minor},
|
| -here's an illustration of a typical sequence:
|
| -
|
| -@smallexample
|
| - <HEAD>
|
| - |
|
| -6.1.50.20020302-cvs
|
| - |
|
| - +--------------------------.
|
| - | <gdb_6_2-branch>
|
| - | |
|
| -6.2.50.20020303-cvs 6.1.90 (draft #1)
|
| - | |
|
| -6.2.50.20020304-cvs 6.1.90.20020304-cvs
|
| - | |
|
| -6.2.50.20020305-cvs 6.1.91 (draft #2)
|
| - | |
|
| -6.2.50.20020306-cvs 6.1.91.20020306-cvs
|
| - | |
|
| -6.2.50.20020307-cvs 6.2 (release)
|
| - | |
|
| -6.2.50.20020308-cvs 6.2.0.20020308-cvs
|
| - | |
|
| -6.2.50.20020309-cvs 6.2.1 (update)
|
| - | |
|
| -6.2.50.20020310-cvs <branch closed>
|
| - |
|
| -6.2.50.20020311-cvs
|
| - |
|
| - +--------------------------.
|
| - | <gdb_6_3-branch>
|
| - | |
|
| -6.3.50.20020312-cvs 6.2.90 (draft #1)
|
| - | |
|
| -@end smallexample
|
| -
|
| -@section Release Branches
|
| -@cindex Release Branches
|
| -
|
| -@value{GDBN} draws a release series (6.2, 6.2.1, @dots{}) from a
|
| -single release branch, and identifies that branch using the @sc{cvs}
|
| -branch tags:
|
| -
|
| -@smallexample
|
| -gdb_@var{major}_@var{minor}-@var{YYYY}@var{MM}@var{DD}-branchpoint
|
| -gdb_@var{major}_@var{minor}-branch
|
| -gdb_@var{major}_@var{minor}-@var{YYYY}@var{MM}@var{DD}-release
|
| -@end smallexample
|
| -
|
| -@emph{Pragmatics: To help identify the date at which a branch or
|
| -release is made, both the branchpoint and release tags include the
|
| -date that they are cut (@var{YYYY}@var{MM}@var{DD}) in the tag. The
|
| -branch tag, denoting the head of the branch, does not need this.}
|
| -
|
| -@section Vendor Branches
|
| -@cindex vendor branches
|
| -
|
| -To avoid version conflicts, vendors are expected to modify the file
|
| -@file{gdb/version.in} to include a vendor unique alphabetic identifier
|
| -(an official @value{GDBN} release never uses alphabetic characters in
|
| -its version identifier). E.g., @samp{6.2widgit2}, or @samp{6.2 (Widgit
|
| -Inc Patch 2)}.
|
| -
|
| -@section Experimental Branches
|
| -@cindex experimental branches
|
| -
|
| -@subsection Guidelines
|
| -
|
| -@value{GDBN} permits the creation of branches, cut from the @sc{cvs}
|
| -repository, for experimental development. Branches make it possible
|
| -for developers to share preliminary work, and maintainers to examine
|
| -significant new developments.
|
| -
|
| -The following are a set of guidelines for creating such branches:
|
| -
|
| -@table @emph
|
| -
|
| -@item a branch has an owner
|
| -The owner can set further policy for a branch, but may not change the
|
| -ground rules. In particular, they can set a policy for commits (be it
|
| -adding more reviewers or deciding who can commit).
|
| -
|
| -@item all commits are posted
|
| -All changes committed to a branch shall also be posted to
|
| -@email{gdb-patches@@sourceware.org, the @value{GDBN} patches
|
| -mailing list}. While commentary on such changes are encouraged, people
|
| -should remember that the changes only apply to a branch.
|
| -
|
| -@item all commits are covered by an assignment
|
| -This ensures that all changes belong to the Free Software Foundation,
|
| -and avoids the possibility that the branch may become contaminated.
|
| -
|
| -@item a branch is focused
|
| -A focused branch has a single objective or goal, and does not contain
|
| -unnecessary or irrelevant changes. Cleanups, where identified, being
|
| -be pushed into the mainline as soon as possible.
|
| -
|
| -@item a branch tracks mainline
|
| -This keeps the level of divergence under control. It also keeps the
|
| -pressure on developers to push cleanups and other stuff into the
|
| -mainline.
|
| -
|
| -@item a branch shall contain the entire @value{GDBN} module
|
| -The @value{GDBN} module @code{gdb} should be specified when creating a
|
| -branch (branches of individual files should be avoided). @xref{Tags}.
|
| -
|
| -@item a branch shall be branded using @file{version.in}
|
| -The file @file{gdb/version.in} shall be modified so that it identifies
|
| -the branch @var{owner} and branch @var{name}, e.g.,
|
| -@samp{6.2.50.20030303_owner_name} or @samp{6.2 (Owner Name)}.
|
| -
|
| -@end table
|
| -
|
| -@subsection Tags
|
| -@anchor{Tags}
|
| -
|
| -To simplify the identification of @value{GDBN} branches, the following
|
| -branch tagging convention is strongly recommended:
|
| -
|
| -@table @code
|
| -
|
| -@item @var{owner}_@var{name}-@var{YYYYMMDD}-branchpoint
|
| -@itemx @var{owner}_@var{name}-@var{YYYYMMDD}-branch
|
| -The branch point and corresponding branch tag. @var{YYYYMMDD} is the
|
| -date that the branch was created. A branch is created using the
|
| -sequence: @anchor{experimental branch tags}
|
| -@smallexample
|
| -cvs rtag @var{owner}_@var{name}-@var{YYYYMMDD}-branchpoint gdb
|
| -cvs rtag -b -r @var{owner}_@var{name}-@var{YYYYMMDD}-branchpoint \
|
| - @var{owner}_@var{name}-@var{YYYYMMDD}-branch gdb
|
| -@end smallexample
|
| -
|
| -@item @var{owner}_@var{name}-@var{yyyymmdd}-mergepoint
|
| -The tagged point, on the mainline, that was used when merging the branch
|
| -on @var{yyyymmdd}. To merge in all changes since the branch was cut,
|
| -use a command sequence like:
|
| -@smallexample
|
| -cvs rtag @var{owner}_@var{name}-@var{yyyymmdd}-mergepoint gdb
|
| -cvs update \
|
| - -j@var{owner}_@var{name}-@var{YYYYMMDD}-branchpoint
|
| - -j@var{owner}_@var{name}-@var{yyyymmdd}-mergepoint
|
| -@end smallexample
|
| -@noindent
|
| -Similar sequences can be used to just merge in changes since the last
|
| -merge.
|
| -
|
| -@end table
|
| -
|
| -@noindent
|
| -For further information on @sc{cvs}, see
|
| -@uref{http://www.gnu.org/software/cvs/, Concurrent Versions System}.
|
| -
|
| -@node Start of New Year Procedure
|
| -@chapter Start of New Year Procedure
|
| -@cindex new year procedure
|
| -
|
| -At the start of each new year, the following actions should be performed:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -Rotate the ChangeLog file
|
| -
|
| -The current @file{ChangeLog} file should be renamed into
|
| -@file{ChangeLog-YYYY} where YYYY is the year that has just passed.
|
| -A new @file{ChangeLog} file should be created, and its contents should
|
| -contain a reference to the previous ChangeLog. The following should
|
| -also be preserved at the end of the new ChangeLog, in order to provide
|
| -the appropriate settings when editing this file with Emacs:
|
| -@smallexample
|
| -Local Variables:
|
| -mode: change-log
|
| -left-margin: 8
|
| -fill-column: 74
|
| -version-control: never
|
| -coding: utf-8
|
| -End:
|
| -@end smallexample
|
| -
|
| -@item
|
| -Add an entry for the newly created ChangeLog file (@file{ChangeLog-YYYY})
|
| -in @file{gdb/config/djgpp/fnchange.lst}.
|
| -
|
| -@item
|
| -Update the copyright year in the startup message
|
| -
|
| -Update the copyright year in:
|
| -@itemize @bullet
|
| - @item
|
| - file @file{top.c}, function @code{print_gdb_version}
|
| - @item
|
| - file @file{gdbserver/server.c}, function @code{gdbserver_version}
|
| - @item
|
| - file @file{gdbserver/gdbreplay.c}, function @code{gdbreplay_version}
|
| -@end itemize
|
| -
|
| -@item
|
| -Run the @file{copyright.py} Python script to add the new year in the copyright
|
| -notices of most source files. This script has been tested with Python
|
| -2.6 and 2.7.
|
| -
|
| -@end itemize
|
| -
|
| -@node Releasing GDB
|
| -
|
| -@chapter Releasing @value{GDBN}
|
| -@cindex making a new release of gdb
|
| -
|
| -@section Branch Commit Policy
|
| -
|
| -The branch commit policy is pretty slack. @value{GDBN} releases 5.0,
|
| -5.1 and 5.2 all used the below:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -The @file{gdb/MAINTAINERS} file still holds.
|
| -@item
|
| -Don't fix something on the branch unless/until it is also fixed in the
|
| -trunk. If this isn't possible, mentioning it in the @file{gdb/PROBLEMS}
|
| -file is better than committing a hack.
|
| -@item
|
| -When considering a patch for the branch, suggested criteria include:
|
| -Does it fix a build? Does it fix the sequence @kbd{break main; run}
|
| -when debugging a static binary?
|
| -@item
|
| -The further a change is from the core of @value{GDBN}, the less likely
|
| -the change will worry anyone (e.g., target specific code).
|
| -@item
|
| -Only post a proposal to change the core of @value{GDBN} after you've
|
| -sent individual bribes to all the people listed in the
|
| -@file{MAINTAINERS} file @t{;-)}
|
| -@end itemize
|
| -
|
| -@emph{Pragmatics: Provided updates are restricted to non-core
|
| -functionality there is little chance that a broken change will be fatal.
|
| -This means that changes such as adding a new architectures or (within
|
| -reason) support for a new host are considered acceptable.}
|
| -
|
| -
|
| -@section Obsoleting code
|
| -
|
| -Before anything else, poke the other developers (and around the source
|
| -code) to see if there is anything that can be removed from @value{GDBN}
|
| -(an old target, an unused file).
|
| -
|
| -Obsolete code is identified by adding an @code{OBSOLETE} prefix to every
|
| -line. Doing this means that it is easy to identify something that has
|
| -been obsoleted when greping through the sources.
|
| -
|
| -The process is done in stages --- this is mainly to ensure that the
|
| -wider @value{GDBN} community has a reasonable opportunity to respond.
|
| -Remember, everything on the Internet takes a week.
|
| -
|
| -@enumerate
|
| -@item
|
| -Post the proposal on @email{gdb@@sourceware.org, the GDB mailing
|
| -list} Creating a bug report to track the task's state, is also highly
|
| -recommended.
|
| -@item
|
| -Wait a week or so.
|
| -@item
|
| -Post the proposal on @email{gdb-announce@@sourceware.org, the GDB
|
| -Announcement mailing list}.
|
| -@item
|
| -Wait a week or so.
|
| -@item
|
| -Go through and edit all relevant files and lines so that they are
|
| -prefixed with the word @code{OBSOLETE}.
|
| -@item
|
| -Wait until the next GDB version, containing this obsolete code, has been
|
| -released.
|
| -@item
|
| -Remove the obsolete code.
|
| -@end enumerate
|
| -
|
| -@noindent
|
| -@emph{Maintainer note: While removing old code is regrettable it is
|
| -hopefully better for @value{GDBN}'s long term development. Firstly it
|
| -helps the developers by removing code that is either no longer relevant
|
| -or simply wrong. Secondly since it removes any history associated with
|
| -the file (effectively clearing the slate) the developer has a much freer
|
| -hand when it comes to fixing broken files.}
|
| -
|
| -
|
| -
|
| -@section Before the Branch
|
| -
|
| -The most important objective at this stage is to find and fix simple
|
| -changes that become a pain to track once the branch is created. For
|
| -instance, configuration problems that stop @value{GDBN} from even
|
| -building. If you can't get the problem fixed, document it in the
|
| -@file{gdb/PROBLEMS} file.
|
| -
|
| -@subheading Prompt for @file{gdb/NEWS}
|
| -
|
| -People always forget. Send a post reminding them but also if you know
|
| -something interesting happened add it yourself. The @code{schedule}
|
| -script will mention this in its e-mail.
|
| -
|
| -@subheading Review @file{gdb/README}
|
| -
|
| -Grab one of the nightly snapshots and then walk through the
|
| -@file{gdb/README} looking for anything that can be improved. The
|
| -@code{schedule} script will mention this in its e-mail.
|
| -
|
| -@subheading Refresh any imported files.
|
| -
|
| -A number of files are taken from external repositories. They include:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -@file{texinfo/texinfo.tex}
|
| -@item
|
| -@file{config.guess} et.@: al.@: (see the top-level @file{MAINTAINERS}
|
| -file)
|
| -@item
|
| -@file{etc/standards.texi}, @file{etc/make-stds.texi}
|
| -@end itemize
|
| -
|
| -@subheading Check the ARI
|
| -
|
| -@uref{http://sourceware.org/gdb/ari,,A.R.I.} is an @code{awk} script
|
| -(Awk Regression Index ;-) that checks for a number of errors and coding
|
| -conventions. The checks include things like using @code{malloc} instead
|
| -of @code{xmalloc} and file naming problems. There shouldn't be any
|
| -regressions.
|
| -
|
| -@subsection Review the bug data base
|
| -
|
| -Close anything obviously fixed.
|
| -
|
| -@subsection Check all cross targets build
|
| -
|
| -The targets are listed in @file{gdb/MAINTAINERS}.
|
| -
|
| -
|
| -@section Cut the Branch
|
| -
|
| -@subheading Create the branch
|
| -
|
| -@smallexample
|
| -$ u=5.1
|
| -$ v=5.2
|
| -$ V=`echo $v | sed 's/\./_/g'`
|
| -$ D=`date -u +%Y-%m-%d`
|
| -$ echo $u $V $D
|
| -5.1 5_2 2002-03-03
|
| -$ echo cvs -f -d :ext:sourceware.org:/cvs/src rtag \
|
| --D $D-gmt gdb_$V-$D-branchpoint insight
|
| -cvs -f -d :ext:sourceware.org:/cvs/src rtag
|
| --D 2002-03-03-gmt gdb_5_2-2002-03-03-branchpoint insight
|
| -$ ^echo ^^
|
| -...
|
| -$ echo cvs -f -d :ext:sourceware.org:/cvs/src rtag \
|
| --b -r gdb_$V-$D-branchpoint gdb_$V-branch insight
|
| -cvs -f -d :ext:sourceware.org:/cvs/src rtag \
|
| --b -r gdb_5_2-2002-03-03-branchpoint gdb_5_2-branch insight
|
| -$ ^echo ^^
|
| -...
|
| -$
|
| -@end smallexample
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -By using @kbd{-D YYYY-MM-DD-gmt}, the branch is forced to an exact
|
| -date/time.
|
| -@item
|
| -The trunk is first tagged so that the branch point can easily be found.
|
| -@item
|
| -Insight, which includes @value{GDBN}, is tagged at the same time.
|
| -@item
|
| -@file{version.in} gets bumped to avoid version number conflicts.
|
| -@item
|
| -The reading of @file{.cvsrc} is disabled using @file{-f}.
|
| -@end itemize
|
| -
|
| -@subheading Update @file{version.in}
|
| -
|
| -@smallexample
|
| -$ u=5.1
|
| -$ v=5.2
|
| -$ V=`echo $v | sed 's/\./_/g'`
|
| -$ echo $u $v$V
|
| -5.1 5_2
|
| -$ cd /tmp
|
| -$ echo cvs -f -d :ext:sourceware.org:/cvs/src co \
|
| --r gdb_$V-branch src/gdb/version.in
|
| -cvs -f -d :ext:sourceware.org:/cvs/src co
|
| - -r gdb_5_2-branch src/gdb/version.in
|
| -$ ^echo ^^
|
| -U src/gdb/version.in
|
| -$ cd src/gdb
|
| -$ echo $u.90-0000-00-00-cvs > version.in
|
| -$ cat version.in
|
| -5.1.90-0000-00-00-cvs
|
| -$ cvs -f commit version.in
|
| -@end smallexample
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -@file{0000-00-00} is used as a date to pump prime the version.in update
|
| -mechanism.
|
| -@item
|
| -@file{.90} and the previous branch version are used as fairly arbitrary
|
| -initial branch version number.
|
| -@end itemize
|
| -
|
| -
|
| -@subheading Update the web and news pages
|
| -
|
| -Something?
|
| -
|
| -@subheading Tweak cron to track the new branch
|
| -
|
| -The file @file{gdbadmin/cron/crontab} contains gdbadmin's cron table.
|
| -This file needs to be updated so that:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -A daily timestamp is added to the file @file{version.in}.
|
| -@item
|
| -The new branch is included in the snapshot process.
|
| -@end itemize
|
| -
|
| -@noindent
|
| -See the file @file{gdbadmin/cron/README} for how to install the updated
|
| -cron table.
|
| -
|
| -The file @file{gdbadmin/ss/README} should also be reviewed to reflect
|
| -any changes. That file is copied to both the branch/ and current/
|
| -snapshot directories.
|
| -
|
| -
|
| -@subheading Update the NEWS and README files
|
| -
|
| -The @file{NEWS} file needs to be updated so that on the branch it refers
|
| -to @emph{changes in the current release} while on the trunk it also
|
| -refers to @emph{changes since the current release}.
|
| -
|
| -The @file{README} file needs to be updated so that it refers to the
|
| -current release.
|
| -
|
| -@subheading Post the branch info
|
| -
|
| -Send an announcement to the mailing lists:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -@email{gdb-announce@@sourceware.org, GDB Announcement mailing list}
|
| -@item
|
| -@email{gdb@@sourceware.org, GDB Discussion mailing list} and
|
| -@email{gdb-testers@@sourceware.org, GDB Testers mailing list}
|
| -@end itemize
|
| -
|
| -@emph{Pragmatics: The branch creation is sent to the announce list to
|
| -ensure that people people not subscribed to the higher volume discussion
|
| -list are alerted.}
|
| -
|
| -The announcement should include:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -The branch tag.
|
| -@item
|
| -How to check out the branch using CVS.
|
| -@item
|
| -The date/number of weeks until the release.
|
| -@item
|
| -The branch commit policy still holds.
|
| -@end itemize
|
| -
|
| -@section Stabilize the branch
|
| -
|
| -Something goes here.
|
| -
|
| -@section Create a Release
|
| -
|
| -The process of creating and then making available a release is broken
|
| -down into a number of stages. The first part addresses the technical
|
| -process of creating a releasable tar ball. The later stages address the
|
| -process of releasing that tar ball.
|
| -
|
| -When making a release candidate just the first section is needed.
|
| -
|
| -@subsection Create a release candidate
|
| -
|
| -The objective at this stage is to create a set of tar balls that can be
|
| -made available as a formal release (or as a less formal release
|
| -candidate).
|
| -
|
| -@subsubheading Freeze the branch
|
| -
|
| -Send out an e-mail notifying everyone that the branch is frozen to
|
| -@email{gdb-patches@@sourceware.org}.
|
| -
|
| -@subsubheading Establish a few defaults.
|
| -
|
| -@smallexample
|
| -$ b=gdb_5_2-branch
|
| -$ v=5.2
|
| -$ t=/sourceware/snapshot-tmp/gdbadmin-tmp
|
| -$ echo $t/$b/$v
|
| -/sourceware/snapshot-tmp/gdbadmin-tmp/gdb_5_2-branch/5.2
|
| -$ mkdir -p $t/$b/$v
|
| -$ cd $t/$b/$v
|
| -$ pwd
|
| -/sourceware/snapshot-tmp/gdbadmin-tmp/gdb_5_2-branch/5.2
|
| -$ which autoconf
|
| -/home/gdbadmin/bin/autoconf
|
| -$
|
| -@end smallexample
|
| -
|
| -@noindent
|
| -Notes:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -Check the @code{autoconf} version carefully. You want to be using the
|
| -version documented in the toplevel @file{README-maintainer-mode} file.
|
| -It is very unlikely that the version of @code{autoconf} installed in
|
| -system directories (e.g., @file{/usr/bin/autoconf}) is correct.
|
| -@end itemize
|
| -
|
| -@subsubheading Check out the relevant modules:
|
| -
|
| -@smallexample
|
| -$ for m in gdb insight
|
| -do
|
| -( mkdir -p $m && cd $m && cvs -q -f -d /cvs/src co -P -r $b $m )
|
| -done
|
| -$
|
| -@end smallexample
|
| -
|
| -@noindent
|
| -Note:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -The reading of @file{.cvsrc} is disabled (@file{-f}) so that there isn't
|
| -any confusion between what is written here and what your local
|
| -@code{cvs} really does.
|
| -@end itemize
|
| -
|
| -@subsubheading Update relevant files.
|
| -
|
| -@table @file
|
| -
|
| -@item gdb/NEWS
|
| -
|
| -Major releases get their comments added as part of the mainline. Minor
|
| -releases should probably mention any significant bugs that were fixed.
|
| -
|
| -Don't forget to include the @file{ChangeLog} entry.
|
| -
|
| -@smallexample
|
| -$ emacs gdb/src/gdb/NEWS
|
| -...
|
| -c-x 4 a
|
| -...
|
| -c-x c-s c-x c-c
|
| -$ cp gdb/src/gdb/NEWS insight/src/gdb/NEWS
|
| -$ cp gdb/src/gdb/ChangeLog insight/src/gdb/ChangeLog
|
| -@end smallexample
|
| -
|
| -@item gdb/README
|
| -
|
| -You'll need to update:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -The version.
|
| -@item
|
| -The update date.
|
| -@item
|
| -Who did it.
|
| -@end itemize
|
| -
|
| -@smallexample
|
| -$ emacs gdb/src/gdb/README
|
| -...
|
| -c-x 4 a
|
| -...
|
| -c-x c-s c-x c-c
|
| -$ cp gdb/src/gdb/README insight/src/gdb/README
|
| -$ cp gdb/src/gdb/ChangeLog insight/src/gdb/ChangeLog
|
| -@end smallexample
|
| -
|
| -@emph{Maintainer note: Hopefully the @file{README} file was reviewed
|
| -before the initial branch was cut so just a simple substitute is needed
|
| -to get it updated.}
|
| -
|
| -@emph{Maintainer note: Other projects generate @file{README} and
|
| -@file{INSTALL} from the core documentation. This might be worth
|
| -pursuing.}
|
| -
|
| -@item gdb/version.in
|
| -
|
| -@smallexample
|
| -$ echo $v > gdb/src/gdb/version.in
|
| -$ cat gdb/src/gdb/version.in
|
| -5.2
|
| -$ emacs gdb/src/gdb/version.in
|
| -...
|
| -c-x 4 a
|
| -... Bump to version ...
|
| -c-x c-s c-x c-c
|
| -$ cp gdb/src/gdb/version.in insight/src/gdb/version.in
|
| -$ cp gdb/src/gdb/ChangeLog insight/src/gdb/ChangeLog
|
| -@end smallexample
|
| -
|
| -@end table
|
| -
|
| -@subsubheading Do the dirty work
|
| -
|
| -This is identical to the process used to create the daily snapshot.
|
| -
|
| -@smallexample
|
| -$ for m in gdb insight
|
| -do
|
| -( cd $m/src && gmake -f src-release $m.tar )
|
| -done
|
| -@end smallexample
|
| -
|
| -If the top level source directory does not have @file{src-release}
|
| -(@value{GDBN} version 5.3.1 or earlier), try these commands instead:
|
| -
|
| -@smallexample
|
| -$ for m in gdb insight
|
| -do
|
| -( cd $m/src && gmake -f Makefile.in $m.tar )
|
| -done
|
| -@end smallexample
|
| -
|
| -@subsubheading Check the source files
|
| -
|
| -You're looking for files that have mysteriously disappeared.
|
| -@kbd{distclean} has the habit of deleting files it shouldn't. Watch out
|
| -for the @file{version.in} update @kbd{cronjob}.
|
| -
|
| -@smallexample
|
| -$ ( cd gdb/src && cvs -f -q -n update )
|
| -M djunpack.bat
|
| -? gdb-5.1.91.tar
|
| -? proto-toplev
|
| -@dots{} lots of generated files @dots{}
|
| -M gdb/ChangeLog
|
| -M gdb/NEWS
|
| -M gdb/README
|
| -M gdb/version.in
|
| -@dots{} lots of generated files @dots{}
|
| -$
|
| -@end smallexample
|
| -
|
| -@noindent
|
| -@emph{Don't worry about the @file{gdb.info-??} or
|
| -@file{gdb/p-exp.tab.c}. They were generated (and yes @file{gdb.info-1}
|
| -was also generated only something strange with CVS means that they
|
| -didn't get suppressed). Fixing it would be nice though.}
|
| -
|
| -@subsubheading Create compressed versions of the release
|
| -
|
| -@smallexample
|
| -$ cp */src/*.tar .
|
| -$ cp */src/*.bz2 .
|
| -$ ls -F
|
| -gdb/ gdb-5.2.tar insight/ insight-5.2.tar
|
| -$ for m in gdb insight
|
| -do
|
| -bzip2 -v -9 -c $m-$v.tar > $m-$v.tar.bz2
|
| -gzip -v -9 -c $m-$v.tar > $m-$v.tar.gz
|
| -done
|
| -$
|
| -@end smallexample
|
| -
|
| -@noindent
|
| -Note:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -A pipe such as @kbd{bunzip2 < xxx.bz2 | gzip -9 > xxx.gz} is not since,
|
| -in that mode, @code{gzip} does not know the name of the file and, hence,
|
| -can not include it in the compressed file. This is also why the release
|
| -process runs @code{tar} and @code{bzip2} as separate passes.
|
| -@end itemize
|
| -
|
| -@subsection Sanity check the tar ball
|
| -
|
| -Pick a popular machine (Solaris/PPC?) and try the build on that.
|
| -
|
| -@smallexample
|
| -$ bunzip2 < gdb-5.2.tar.bz2 | tar xpf -
|
| -$ cd gdb-5.2
|
| -$ ./configure
|
| -$ make
|
| -@dots{}
|
| -$ ./gdb/gdb ./gdb/gdb
|
| -GNU gdb 5.2
|
| -@dots{}
|
| -(gdb) b main
|
| -Breakpoint 1 at 0x80732bc: file main.c, line 734.
|
| -(gdb) run
|
| -Starting program: /tmp/gdb-5.2/gdb/gdb
|
| -
|
| -Breakpoint 1, main (argc=1, argv=0xbffff8b4) at main.c:734
|
| -734 catch_errors (captured_main, &args, "", RETURN_MASK_ALL);
|
| -(gdb) print args
|
| -$1 = @{argc = 136426532, argv = 0x821b7f0@}
|
| -(gdb)
|
| -@end smallexample
|
| -
|
| -@subsection Make a release candidate available
|
| -
|
| -If this is a release candidate then the only remaining steps are:
|
| -
|
| -@enumerate
|
| -@item
|
| -Commit @file{version.in} and @file{ChangeLog}
|
| -@item
|
| -Tweak @file{version.in} (and @file{ChangeLog} to read
|
| -@var{L}.@var{M}.@var{N}-0000-00-00-cvs so that the version update
|
| -process can restart.
|
| -@item
|
| -Make the release candidate available in
|
| -@uref{ftp://sourceware.org/pub/gdb/snapshots/branch}
|
| -@item
|
| -Notify the relevant mailing lists ( @email{gdb@@sourceware.org} and
|
| -@email{gdb-testers@@sourceware.org} that the candidate is available.
|
| -@end enumerate
|
| -
|
| -@subsection Make a formal release available
|
| -
|
| -(And you thought all that was required was to post an e-mail.)
|
| -
|
| -@subsubheading Install on sware
|
| -
|
| -Copy the new files to both the release and the old release directory:
|
| -
|
| -@smallexample
|
| -$ cp *.bz2 *.gz ~ftp/pub/gdb/old-releases/
|
| -$ cp *.bz2 *.gz ~ftp/pub/gdb/releases
|
| -@end smallexample
|
| -
|
| -@noindent
|
| -Clean up the releases directory so that only the most recent releases
|
| -are available (e.g.@: keep 5.2 and 5.2.1 but remove 5.1):
|
| -
|
| -@smallexample
|
| -$ cd ~ftp/pub/gdb/releases
|
| -$ rm @dots{}
|
| -@end smallexample
|
| -
|
| -@noindent
|
| -Update the file @file{README} and @file{.message} in the releases
|
| -directory:
|
| -
|
| -@smallexample
|
| -$ vi README
|
| -@dots{}
|
| -$ rm -f .message
|
| -$ ln README .message
|
| -@end smallexample
|
| -
|
| -@subsubheading Update the web pages.
|
| -
|
| -@table @file
|
| -
|
| -@item htdocs/download/ANNOUNCEMENT
|
| -This file, which is posted as the official announcement, includes:
|
| -@itemize @bullet
|
| -@item
|
| -General announcement.
|
| -@item
|
| -News. If making an @var{M}.@var{N}.1 release, retain the news from
|
| -earlier @var{M}.@var{N} release.
|
| -@item
|
| -Errata.
|
| -@end itemize
|
| -
|
| -@item htdocs/index.html
|
| -@itemx htdocs/news/index.html
|
| -@itemx htdocs/download/index.html
|
| -These files include:
|
| -@itemize @bullet
|
| -@item
|
| -Announcement of the most recent release.
|
| -@item
|
| -News entry (remember to update both the top level and the news directory).
|
| -@end itemize
|
| -These pages also need to be regenerate using @code{index.sh}.
|
| -
|
| -@item download/onlinedocs/
|
| -You need to find the magic command that is used to generate the online
|
| -docs from the @file{.tar.bz2}. The best way is to look in the output
|
| -from one of the nightly @code{cron} jobs and then just edit accordingly.
|
| -Something like:
|
| -
|
| -@smallexample
|
| -$ ~/ss/update-web-docs \
|
| - ~ftp/pub/gdb/releases/gdb-5.2.tar.bz2 \
|
| - $PWD/www \
|
| - /www/sourceware/htdocs/gdb/download/onlinedocs \
|
| - gdb
|
| -@end smallexample
|
| -
|
| -@item download/ari/
|
| -Just like the online documentation. Something like:
|
| -
|
| -@smallexample
|
| -$ /bin/sh ~/ss/update-web-ari \
|
| - ~ftp/pub/gdb/releases/gdb-5.2.tar.bz2 \
|
| - $PWD/www \
|
| - /www/sourceware/htdocs/gdb/download/ari \
|
| - gdb
|
| -@end smallexample
|
| -
|
| -@end table
|
| -
|
| -@subsubheading Shadow the pages onto gnu
|
| -
|
| -Something goes here.
|
| -
|
| -
|
| -@subsubheading Install the @value{GDBN} tar ball on GNU
|
| -
|
| -At the time of writing, the GNU machine was @kbd{gnudist.gnu.org} in
|
| -@file{~ftp/gnu/gdb}.
|
| -
|
| -@subsubheading Make the @file{ANNOUNCEMENT}
|
| -
|
| -Post the @file{ANNOUNCEMENT} file you created above to:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -@email{gdb-announce@@sourceware.org, GDB Announcement mailing list}
|
| -@item
|
| -@email{info-gnu@@gnu.org, General GNU Announcement list} (but delay it a
|
| -day or so to let things get out)
|
| -@item
|
| -@email{bug-gdb@@gnu.org, GDB Bug Report mailing list}
|
| -@end itemize
|
| -
|
| -@subsection Cleanup
|
| -
|
| -The release is out but you're still not finished.
|
| -
|
| -@subsubheading Commit outstanding changes
|
| -
|
| -In particular you'll need to commit any changes to:
|
| -
|
| -@itemize @bullet
|
| -@item
|
| -@file{gdb/ChangeLog}
|
| -@item
|
| -@file{gdb/version.in}
|
| -@item
|
| -@file{gdb/NEWS}
|
| -@item
|
| -@file{gdb/README}
|
| -@end itemize
|
| -
|
| -@subsubheading Tag the release
|
| -
|
| -Something like:
|
| -
|
| -@smallexample
|
| -$ d=`date -u +%Y-%m-%d`
|
| -$ echo $d
|
| -2002-01-24
|
| -$ ( cd insight/src/gdb && cvs -f -q update )
|
| -$ ( cd insight/src && cvs -f -q tag gdb_5_2-$d-release )
|
| -@end smallexample
|
| -
|
| -Insight is used since that contains more of the release than
|
| -@value{GDBN}.
|
| -
|
| -@subsubheading Mention the release on the trunk
|
| -
|
| -Just put something in the @file{ChangeLog} so that the trunk also
|
| -indicates when the release was made.
|
| -
|
| -@subsubheading Restart @file{gdb/version.in}
|
| -
|
| -If @file{gdb/version.in} does not contain an ISO date such as
|
| -@kbd{2002-01-24} then the daily @code{cronjob} won't update it. Having
|
| -committed all the release changes it can be set to
|
| -@file{5.2.0_0000-00-00-cvs} which will restart things (yes the @kbd{_}
|
| -is important - it affects the snapshot process).
|
| -
|
| -Don't forget the @file{ChangeLog}.
|
| -
|
| -@subsubheading Merge into trunk
|
| -
|
| -The files committed to the branch may also need changes merged into the
|
| -trunk.
|
| -
|
| -@subsubheading Revise the release schedule
|
| -
|
| -Post a revised release schedule to @email{gdb@@sourceware.org, GDB
|
| -Discussion List} with an updated announcement. The schedule can be
|
| -generated by running:
|
| -
|
| -@smallexample
|
| -$ ~/ss/schedule `date +%s` schedule
|
| -@end smallexample
|
| -
|
| -@noindent
|
| -The first parameter is approximate date/time in seconds (from the epoch)
|
| -of the most recent release.
|
| -
|
| -Also update the schedule @code{cronjob}.
|
| -
|
| -@section Post release
|
| -
|
| -Remove any @code{OBSOLETE} code.
|
| -
|
| -@node Testsuite
|
| -
|
| -@chapter Testsuite
|
| -@cindex test suite
|
| -
|
| -The testsuite is an important component of the @value{GDBN} package.
|
| -While it is always worthwhile to encourage user testing, in practice
|
| -this is rarely sufficient; users typically use only a small subset of
|
| -the available commands, and it has proven all too common for a change
|
| -to cause a significant regression that went unnoticed for some time.
|
| -
|
| -The @value{GDBN} testsuite uses the DejaGNU testing framework. The
|
| -tests themselves are calls to various @code{Tcl} procs; the framework
|
| -runs all the procs and summarizes the passes and fails.
|
| -
|
| -@section Using the Testsuite
|
| -
|
| -@cindex running the test suite
|
| -To run the testsuite, simply go to the @value{GDBN} object directory (or to the
|
| -testsuite's objdir) and type @code{make check}. This just sets up some
|
| -environment variables and invokes DejaGNU's @code{runtest} script. While
|
| -the testsuite is running, you'll get mentions of which test file is in use,
|
| -and a mention of any unexpected passes or fails. When the testsuite is
|
| -finished, you'll get a summary that looks like this:
|
| -
|
| -@smallexample
|
| - === gdb Summary ===
|
| -
|
| -# of expected passes 6016
|
| -# of unexpected failures 58
|
| -# of unexpected successes 5
|
| -# of expected failures 183
|
| -# of unresolved testcases 3
|
| -# of untested testcases 5
|
| -@end smallexample
|
| -
|
| -To run a specific test script, type:
|
| -@example
|
| -make check RUNTESTFLAGS='@var{tests}'
|
| -@end example
|
| -where @var{tests} is a list of test script file names, separated by
|
| -spaces.
|
| -
|
| -If you use GNU make, you can use its @option{-j} option to run the
|
| -testsuite in parallel. This can greatly reduce the amount of time it
|
| -takes for the testsuite to run. In this case, if you set
|
| -@code{RUNTESTFLAGS} then, by default, the tests will be run serially
|
| -even under @option{-j}. You can override this and force a parallel run
|
| -by setting the @code{make} variable @code{FORCE_PARALLEL} to any
|
| -non-empty value. Note that the parallel @kbd{make check} assumes
|
| -that you want to run the entire testsuite, so it is not compatible
|
| -with some dejagnu options, like @option{--directory}.
|
| -
|
| -The ideal test run consists of expected passes only; however, reality
|
| -conspires to keep us from this ideal. Unexpected failures indicate
|
| -real problems, whether in @value{GDBN} or in the testsuite. Expected
|
| -failures are still failures, but ones which have been decided are too
|
| -hard to deal with at the time; for instance, a test case might work
|
| -everywhere except on AIX, and there is no prospect of the AIX case
|
| -being fixed in the near future. Expected failures should not be added
|
| -lightly, since you may be masking serious bugs in @value{GDBN}.
|
| -Unexpected successes are expected fails that are passing for some
|
| -reason, while unresolved and untested cases often indicate some minor
|
| -catastrophe, such as the compiler being unable to deal with a test
|
| -program.
|
| -
|
| -When making any significant change to @value{GDBN}, you should run the
|
| -testsuite before and after the change, to confirm that there are no
|
| -regressions. Note that truly complete testing would require that you
|
| -run the testsuite with all supported configurations and a variety of
|
| -compilers; however this is more than really necessary. In many cases
|
| -testing with a single configuration is sufficient. Other useful
|
| -options are to test one big-endian (Sparc) and one little-endian (x86)
|
| -host, a cross config with a builtin simulator (powerpc-eabi,
|
| -mips-elf), or a 64-bit host (Alpha).
|
| -
|
| -If you add new functionality to @value{GDBN}, please consider adding
|
| -tests for it as well; this way future @value{GDBN} hackers can detect
|
| -and fix their changes that break the functionality you added.
|
| -Similarly, if you fix a bug that was not previously reported as a test
|
| -failure, please add a test case for it. Some cases are extremely
|
| -difficult to test, such as code that handles host OS failures or bugs
|
| -in particular versions of compilers, and it's OK not to try to write
|
| -tests for all of those.
|
| -
|
| -DejaGNU supports separate build, host, and target machines. However,
|
| -some @value{GDBN} test scripts do not work if the build machine and
|
| -the host machine are not the same. In such an environment, these scripts
|
| -will give a result of ``UNRESOLVED'', like this:
|
| -
|
| -@smallexample
|
| -UNRESOLVED: gdb.base/example.exp: This test script does not work on a remote host.
|
| -@end smallexample
|
| -
|
| -@section Testsuite Parameters
|
| -
|
| -Several variables exist to modify the behavior of the testsuite.
|
| -
|
| -@itemize @bullet
|
| -
|
| -@item @code{TRANSCRIPT}
|
| -
|
| -Sometimes it is convenient to get a transcript of the commands which
|
| -the testsuite sends to @value{GDBN}. For example, if @value{GDBN}
|
| -crashes during testing, a transcript can be used to more easily
|
| -reconstruct the failure when running @value{GDBN} under @value{GDBN}.
|
| -
|
| -You can instruct the @value{GDBN} testsuite to write transcripts by
|
| -setting the DejaGNU variable @code{TRANSCRIPT} (to any value)
|
| -before invoking @code{runtest} or @kbd{make check}. The transcripts
|
| -will be written into DejaGNU's output directory. One transcript will
|
| -be made for each invocation of @value{GDBN}; they will be named
|
| -@file{transcript.@var{n}}, where @var{n} is an integer. The first
|
| -line of the transcript file will show how @value{GDBN} was invoked;
|
| -each subsequent line is a command sent as input to @value{GDBN}.
|
| -
|
| -@smallexample
|
| -make check RUNTESTFLAGS=TRANSCRIPT=y
|
| -@end smallexample
|
| -
|
| -Note that the transcript is not always complete. In particular, tests
|
| -of completion can yield partial command lines.
|
| -
|
| -@item @code{GDB}
|
| -
|
| -Sometimes one wishes to test a different @value{GDBN} than the one in the build
|
| -directory. For example, one may wish to run the testsuite on
|
| -@file{/usr/bin/gdb}.
|
| -
|
| -@smallexample
|
| -make check RUNTESTFLAGS=GDB=/usr/bin/gdb
|
| -@end smallexample
|
| -
|
| -@item @code{GDBSERVER}
|
| -
|
| -When testing a different @value{GDBN}, it is often useful to also test a
|
| -different gdbserver.
|
| -
|
| -@smallexample
|
| -make check RUNTESTFLAGS="GDB=/usr/bin/gdb GDBSERVER=/usr/bin/gdbserver"
|
| -@end smallexample
|
| -
|
| -@item @code{INTERNAL_GDBFLAGS}
|
| -
|
| -When running the testsuite normally one doesn't want whatever is in
|
| -@file{~/.gdbinit} to interfere with the tests, therefore the test harness
|
| -passes @option{-nx} to @value{GDBN}. One also doesn't want any windowed
|
| -version of @value{GDBN}, e.g., @samp{gdb -tui}, to run.
|
| -This is achieved via @code{INTERNAL_GDBFLAGS}.
|
| -
|
| -@smallexample
|
| -set INTERNAL_GDBFLAGS "-nw -nx"
|
| -@end smallexample
|
| -
|
| -This is all well and good, except when testing an installed @value{GDBN}
|
| -that has been configured with @option{--with-system-gdbinit}. Here one
|
| -does not want @file{~/.gdbinit} loaded but one may want the system
|
| -@file{.gdbinit} file loaded. This can be achieved by pointing @code{$HOME}
|
| -at a directory without a @file{.gdbinit} and by overriding
|
| -@code{INTERNAL_GDBFLAGS} and removing @option{-nx}.
|
| -
|
| -@smallexample
|
| -cd testsuite
|
| -HOME=`pwd` runtest \
|
| - GDB=/usr/bin/gdb \
|
| - GDBSERVER=/usr/bin/gdbserver \
|
| - INTERNAL_GDBFLAGS=-nw
|
| -@end smallexample
|
| -
|
| -@end itemize
|
| -
|
| -There are two ways to run the testsuite and pass additional parameters
|
| -to DejaGnu. The first is with @kbd{make check} and specifying the
|
| -makefile variable @samp{RUNTESTFLAGS}.
|
| -
|
| -@smallexample
|
| -make check RUNTESTFLAGS=TRANSCRIPT=y
|
| -@end smallexample
|
| -
|
| -The second is to cd to the @file{testsuite} directory and invoke the DejaGnu
|
| -@command{runtest} command directly.
|
| -
|
| -@smallexample
|
| -cd testsuite
|
| -make site.exp
|
| -runtest TRANSCRIPT=y
|
| -@end smallexample
|
| -
|
| -@section Testsuite Configuration
|
| -@cindex Testsuite Configuration
|
| -
|
| -It is possible to adjust the behavior of the testsuite by defining
|
| -the global variables listed below, either in a @file{site.exp} file,
|
| -or in a board file.
|
| -
|
| -@itemize @bullet
|
| -
|
| -@item @code{gdb_test_timeout}
|
| -
|
| -Defining this variable changes the default timeout duration used during
|
| -communication with @value{GDBN}. More specifically, the global variable
|
| -used during testing is @code{timeout}, but this variable gets reset to
|
| -@code{gdb_test_timeout} at the beginning of each testcase, making sure
|
| -that any local change to @code{timeout} in a testcase does not affect
|
| -subsequent testcases.
|
| -
|
| -This global variable comes in handy when the debugger is slower than
|
| -normal due to the testing environment, triggering unexpected @code{TIMEOUT}
|
| -test failures. Examples include when testing on a remote machine, or
|
| -against a system where communications are slow.
|
| -
|
| -If not specifically defined, this variable gets automatically defined
|
| -to the same value as @code{timeout} during the testsuite initialization.
|
| -The default value of the timeout is defined in the file
|
| -@file{gdb/testsuite/config/unix.exp} that is part of the @value{GDBN}
|
| -test suite@footnote{If you are using a board file, it could override
|
| -the test-suite default; search the board file for "timeout".}.
|
| -
|
| -@end itemize
|
| -
|
| -@section Testsuite Organization
|
| -
|
| -@cindex test suite organization
|
| -The testsuite is entirely contained in @file{gdb/testsuite}. While the
|
| -testsuite includes some makefiles and configury, these are very minimal,
|
| -and used for little besides cleaning up, since the tests themselves
|
| -handle the compilation of the programs that @value{GDBN} will run. The file
|
| -@file{testsuite/lib/gdb.exp} contains common utility procs useful for
|
| -all @value{GDBN} tests, while the directory @file{testsuite/config} contains
|
| -configuration-specific files, typically used for special-purpose
|
| -definitions of procs like @code{gdb_load} and @code{gdb_start}.
|
| -
|
| -The tests themselves are to be found in @file{testsuite/gdb.*} and
|
| -subdirectories of those. The names of the test files must always end
|
| -with @file{.exp}. DejaGNU collects the test files by wildcarding
|
| -in the test directories, so both subdirectories and individual files
|
| -get chosen and run in alphabetical order.
|
| -
|
| -The following table lists the main types of subdirectories and what they
|
| -are for. Since DejaGNU finds test files no matter where they are
|
| -located, and since each test file sets up its own compilation and
|
| -execution environment, this organization is simply for convenience and
|
| -intelligibility.
|
| -
|
| -@table @file
|
| -@item gdb.base
|
| -This is the base testsuite. The tests in it should apply to all
|
| -configurations of @value{GDBN} (but generic native-only tests may live here).
|
| -The test programs should be in the subset of C that is valid K&R,
|
| -ANSI/ISO, and C@t{++} (@code{#ifdef}s are allowed if necessary, for instance
|
| -for prototypes).
|
| -
|
| -@item gdb.@var{lang}
|
| -Language-specific tests for any language @var{lang} besides C. Examples are
|
| -@file{gdb.cp} and @file{gdb.java}.
|
| -
|
| -@item gdb.@var{platform}
|
| -Non-portable tests. The tests are specific to a specific configuration
|
| -(host or target), such as HP-UX or eCos. Example is @file{gdb.hp}, for
|
| -HP-UX.
|
| -
|
| -@item gdb.@var{compiler}
|
| -Tests specific to a particular compiler. As of this writing (June
|
| -1999), there aren't currently any groups of tests in this category that
|
| -couldn't just as sensibly be made platform-specific, but one could
|
| -imagine a @file{gdb.gcc}, for tests of @value{GDBN}'s handling of GCC
|
| -extensions.
|
| -
|
| -@item gdb.@var{subsystem}
|
| -Tests that exercise a specific @value{GDBN} subsystem in more depth. For
|
| -instance, @file{gdb.disasm} exercises various disassemblers, while
|
| -@file{gdb.stabs} tests pathways through the stabs symbol reader.
|
| -@end table
|
| -
|
| -@section Writing Tests
|
| -@cindex writing tests
|
| -
|
| -In many areas, the @value{GDBN} tests are already quite comprehensive; you
|
| -should be able to copy existing tests to handle new cases.
|
| -
|
| -You should try to use @code{gdb_test} whenever possible, since it
|
| -includes cases to handle all the unexpected errors that might happen.
|
| -However, it doesn't cost anything to add new test procedures; for
|
| -instance, @file{gdb.base/exprs.exp} defines a @code{test_expr} that
|
| -calls @code{gdb_test} multiple times.
|
| -
|
| -Only use @code{send_gdb} and @code{gdb_expect} when absolutely
|
| -necessary. Even if @value{GDBN} has several valid responses to
|
| -a command, you can use @code{gdb_test_multiple}. Like @code{gdb_test},
|
| -@code{gdb_test_multiple} recognizes internal errors and unexpected
|
| -prompts.
|
| -
|
| -Do not write tests which expect a literal tab character from @value{GDBN}.
|
| -On some operating systems (e.g.@: OpenBSD) the TTY layer expands tabs to
|
| -spaces, so by the time @value{GDBN}'s output reaches expect the tab is gone.
|
| -
|
| -The source language programs do @emph{not} need to be in a consistent
|
| -style. Since @value{GDBN} is used to debug programs written in many different
|
| -styles, it's worth having a mix of styles in the testsuite; for
|
| -instance, some @value{GDBN} bugs involving the display of source lines would
|
| -never manifest themselves if the programs used GNU coding style
|
| -uniformly.
|
| -
|
| -Some testcase results need more detailed explanation:
|
| -
|
| -@table @code
|
| -@item KFAIL
|
| -Known problem of @value{GDBN} itself. You must specify the @value{GDBN} bug
|
| -report number like in these sample tests:
|
| -@smallexample
|
| -kfail "gdb/13392" "continue to marker 2"
|
| -@end smallexample
|
| -or
|
| -@smallexample
|
| -setup_kfail gdb/13392 "*-*-*"
|
| -kfail "continue to marker 2"
|
| -@end smallexample
|
| -
|
| -@item XFAIL
|
| -Known problem of environment. This typically includes @value{NGCC} but it
|
| -includes also many other system components which cannot be fixed in the
|
| -@value{GDBN} project. Sample test with sanity check not knowing the specific
|
| -cause of the problem:
|
| -@smallexample
|
| -# On x86_64 it is commonly about 4MB.
|
| -if @{$stub_size > 25000000@} @{
|
| - xfail "stub size $stub_size is too large"
|
| - return
|
| -@}
|
| -@end smallexample
|
| -
|
| -You should provide bug report number for the failing component of the
|
| -environment, if such bug report is available:
|
| -@smallexample
|
| -if @{[test_compiler_info @{gcc-[0-3]-*@}]
|
| - || [test_compiler_info @{gcc-4-[0-5]-*@}]@} @{
|
| - setup_xfail "gcc/46955" *-*-*
|
| -@}
|
| -gdb_test "python print ttype.template_argument(2)" "&C::c"
|
| -@end smallexample
|
| -@end table
|
| -
|
| -@section Board settings
|
| -In @value{GDBN} testsuite, the tests can be configured or customized in the board
|
| -file by means of @dfn{Board Settings}. Each setting should be consulted by
|
| -test cases that depend on the corresponding feature.
|
| -
|
| -Here are the supported board settings:
|
| -
|
| -@table @code
|
| -
|
| -@item gdb,cannot_call_functions
|
| -The board does not support inferior call, that is, invoking inferior functions
|
| -in @value{GDBN}.
|
| -@item gdb,can_reverse
|
| -The board supports reverse execution.
|
| -@item gdb,no_hardware_watchpoints
|
| -The board does not support hardware watchpoints.
|
| -@item gdb,nofileio
|
| -@value{GDBN} is unable to intercept target file operations in remote and perform
|
| -them on the host.
|
| -@item gdb,noinferiorio
|
| -The board is unable to provide I/O capability to the inferior.
|
| -@c @item gdb,noresults
|
| -@c NEED DOCUMENT.
|
| -@item gdb,nosignals
|
| -The board does not support signals.
|
| -@item gdb,skip_huge_test
|
| -Skip time-consuming tests on the board with slow connection.
|
| -@item gdb,skip_float_tests
|
| -Skip tests related to float points on target board.
|
| -@item gdb,use_precord
|
| -The board supports process record.
|
| -@item gdb_server_prog
|
| -The location of GDBserver. If GDBserver somewhere other than its default
|
| -location is used in test, specify the location of GDBserver in this variable.
|
| -The location is a file name of GDBserver that can be either absolute or
|
| -relative to testsuite subdirectory in build directory.
|
| -@item in_proc_agent
|
| -The location of in-process agent. If in-process agent other than its default
|
| -location is used in test, specify the location of in-process agent in
|
| -this variable. The location is a file name of in-process agent that can be
|
| -either absolute or relative to testsuite subdirectory in build directory.
|
| -@item noargs
|
| -@value{GDBN} does not support argument passing for inferior.
|
| -@item no_long_long
|
| -The board does not support type @code{long long}.
|
| -@c @item use_cygmon
|
| -@c NEED DOCUMENT.
|
| -@item use_gdb_stub
|
| -The tests are running with gdb stub.
|
| -@end table
|
| -
|
| -@node Hints
|
| -
|
| -@chapter Hints
|
| -
|
| -Check the @file{README} file, it often has useful information that does not
|
| -appear anywhere else in the directory.
|
| -
|
| -@menu
|
| -* Getting Started:: Getting started working on @value{GDBN}
|
| -* Debugging GDB:: Debugging @value{GDBN} with itself
|
| -@end menu
|
| -
|
| -@node Getting Started
|
| -
|
| -@section Getting Started
|
| -
|
| -@value{GDBN} is a large and complicated program, and if you first starting to
|
| -work on it, it can be hard to know where to start. Fortunately, if you
|
| -know how to go about it, there are ways to figure out what is going on.
|
| -
|
| -This manual, the @value{GDBN} Internals manual, has information which applies
|
| -generally to many parts of @value{GDBN}.
|
| -
|
| -Information about particular functions or data structures are located in
|
| -comments with those functions or data structures. If you run across a
|
| -function or a global variable which does not have a comment correctly
|
| -explaining what is does, this can be thought of as a bug in @value{GDBN}; feel
|
| -free to submit a bug report, with a suggested comment if you can figure
|
| -out what the comment should say. If you find a comment which is
|
| -actually wrong, be especially sure to report that.
|
| -
|
| -Comments explaining the function of macros defined in host, target, or
|
| -native dependent files can be in several places. Sometimes they are
|
| -repeated every place the macro is defined. Sometimes they are where the
|
| -macro is used. Sometimes there is a header file which supplies a
|
| -default definition of the macro, and the comment is there. This manual
|
| -also documents all the available macros.
|
| -@c (@pxref{Host Conditionals}, @pxref{Target
|
| -@c Conditionals}, @pxref{Native Conditionals}, and @pxref{Obsolete
|
| -@c Conditionals})
|
| -
|
| -Start with the header files. Once you have some idea of how
|
| -@value{GDBN}'s internal symbol tables are stored (see @file{symtab.h},
|
| -@file{gdbtypes.h}), you will find it much easier to understand the
|
| -code which uses and creates those symbol tables.
|
| -
|
| -You may wish to process the information you are getting somehow, to
|
| -enhance your understanding of it. Summarize it, translate it to another
|
| -language, add some (perhaps trivial or non-useful) feature to @value{GDBN}, use
|
| -the code to predict what a test case would do and write the test case
|
| -and verify your prediction, etc. If you are reading code and your eyes
|
| -are starting to glaze over, this is a sign you need to use a more active
|
| -approach.
|
| -
|
| -Once you have a part of @value{GDBN} to start with, you can find more
|
| -specifically the part you are looking for by stepping through each
|
| -function with the @code{next} command. Do not use @code{step} or you
|
| -will quickly get distracted; when the function you are stepping through
|
| -calls another function try only to get a big-picture understanding
|
| -(perhaps using the comment at the beginning of the function being
|
| -called) of what it does. This way you can identify which of the
|
| -functions being called by the function you are stepping through is the
|
| -one which you are interested in. You may need to examine the data
|
| -structures generated at each stage, with reference to the comments in
|
| -the header files explaining what the data structures are supposed to
|
| -look like.
|
| -
|
| -Of course, this same technique can be used if you are just reading the
|
| -code, rather than actually stepping through it. The same general
|
| -principle applies---when the code you are looking at calls something
|
| -else, just try to understand generally what the code being called does,
|
| -rather than worrying about all its details.
|
| -
|
| -@cindex command implementation
|
| -A good place to start when tracking down some particular area is with
|
| -a command which invokes that feature. Suppose you want to know how
|
| -single-stepping works. As a @value{GDBN} user, you know that the
|
| -@code{step} command invokes single-stepping. The command is invoked
|
| -via command tables (see @file{command.h}); by convention the function
|
| -which actually performs the command is formed by taking the name of
|
| -the command and adding @samp{_command}, or in the case of an
|
| -@code{info} subcommand, @samp{_info}. For example, the @code{step}
|
| -command invokes the @code{step_command} function and the @code{info
|
| -display} command invokes @code{display_info}. When this convention is
|
| -not followed, you might have to use @code{grep} or @kbd{M-x
|
| -tags-search} in emacs, or run @value{GDBN} on itself and set a
|
| -breakpoint in @code{execute_command}.
|
| -
|
| -@cindex @code{bug-gdb} mailing list
|
| -If all of the above fail, it may be appropriate to ask for information
|
| -on @code{bug-gdb}. But @emph{never} post a generic question like ``I was
|
| -wondering if anyone could give me some tips about understanding
|
| -@value{GDBN}''---if we had some magic secret we would put it in this manual.
|
| -Suggestions for improving the manual are always welcome, of course.
|
| -
|
| -@node Debugging GDB
|
| -
|
| -@section Debugging @value{GDBN} with itself
|
| -@cindex debugging @value{GDBN}
|
| -
|
| -If @value{GDBN} is limping on your machine, this is the preferred way to get it
|
| -fully functional. Be warned that in some ancient Unix systems, like
|
| -Ultrix 4.2, a program can't be running in one process while it is being
|
| -debugged in another. Rather than typing the command @kbd{@w{./gdb
|
| -./gdb}}, which works on Suns and such, you can copy @file{gdb} to
|
| -@file{gdb2} and then type @kbd{@w{./gdb ./gdb2}}.
|
| -
|
| -When you run @value{GDBN} in the @value{GDBN} source directory, it will read
|
| -@file{gdb-gdb.gdb} file (plus possibly @file{gdb-gdb.py} file) that sets up
|
| -some simple things to make debugging gdb easier. The @code{info} command, when
|
| -executed without a subcommand in a @value{GDBN} being debugged by gdb, will pop
|
| -you back up to the top level gdb. See @file{gdb-gdb.gdb} for details.
|
| -
|
| -If you use emacs, you will probably want to do a @code{make TAGS} after
|
| -you configure your distribution; this will put the machine dependent
|
| -routines for your local machine where they will be accessed first by
|
| -@kbd{M-.}
|
| -
|
| -Also, make sure that you've either compiled @value{GDBN} with your local cc, or
|
| -have run @code{fixincludes} if you are compiling with gcc.
|
| -
|
| -@section Submitting Patches
|
| -
|
| -@cindex submitting patches
|
| -Thanks for thinking of offering your changes back to the community of
|
| -@value{GDBN} users. In general we like to get well designed enhancements.
|
| -Thanks also for checking in advance about the best way to transfer the
|
| -changes.
|
| -
|
| -The @value{GDBN} maintainers will only install ``cleanly designed'' patches.
|
| -This manual summarizes what we believe to be clean design for @value{GDBN}.
|
| -
|
| -If the maintainers don't have time to put the patch in when it arrives,
|
| -or if there is any question about a patch, it goes into a large queue
|
| -with everyone else's patches and bug reports.
|
| -
|
| -@cindex legal papers for code contributions
|
| -The legal issue is that to incorporate substantial changes requires a
|
| -copyright assignment from you and/or your employer, granting ownership
|
| -of the changes to the Free Software Foundation. You can get the
|
| -standard documents for doing this by sending mail to @code{gnu@@gnu.org}
|
| -and asking for it. We recommend that people write in "All programs
|
| -owned by the Free Software Foundation" as "NAME OF PROGRAM", so that
|
| -changes in many programs (not just @value{GDBN}, but GAS, Emacs, GCC,
|
| -etc) can be
|
| -contributed with only one piece of legalese pushed through the
|
| -bureaucracy and filed with the FSF. We can't start merging changes until
|
| -this paperwork is received by the FSF (their rules, which we follow
|
| -since we maintain it for them).
|
| -
|
| -Technically, the easiest way to receive changes is to receive each
|
| -feature as a small context diff or unidiff, suitable for @code{patch}.
|
| -Each message sent to me should include the changes to C code and
|
| -header files for a single feature, plus @file{ChangeLog} entries for
|
| -each directory where files were modified, and diffs for any changes
|
| -needed to the manuals (@file{gdb/doc/gdb.texinfo} or
|
| -@file{gdb/doc/gdbint.texinfo}). If there are a lot of changes for a
|
| -single feature, they can be split down into multiple messages.
|
| -
|
| -In this way, if we read and like the feature, we can add it to the
|
| -sources with a single patch command, do some testing, and check it in.
|
| -If you leave out the @file{ChangeLog}, we have to write one. If you leave
|
| -out the doc, we have to puzzle out what needs documenting. Etc., etc.
|
| -
|
| -The reason to send each change in a separate message is that we will not
|
| -install some of the changes. They'll be returned to you with questions
|
| -or comments. If we're doing our job correctly, the message back to you
|
| -will say what you have to fix in order to make the change acceptable.
|
| -The reason to have separate messages for separate features is so that
|
| -the acceptable changes can be installed while one or more changes are
|
| -being reworked. If multiple features are sent in a single message, we
|
| -tend to not put in the effort to sort out the acceptable changes from
|
| -the unacceptable, so none of the features get installed until all are
|
| -acceptable.
|
| -
|
| -If this sounds painful or authoritarian, well, it is. But we get a lot
|
| -of bug reports and a lot of patches, and many of them don't get
|
| -installed because we don't have the time to finish the job that the bug
|
| -reporter or the contributor could have done. Patches that arrive
|
| -complete, working, and well designed, tend to get installed on the day
|
| -they arrive. The others go into a queue and get installed as time
|
| -permits, which, since the maintainers have many demands to meet, may not
|
| -be for quite some time.
|
| -
|
| -Please send patches directly to
|
| -@email{gdb-patches@@sourceware.org, the @value{GDBN} maintainers}.
|
| -
|
| -@section Build Script
|
| -
|
| -@cindex build script
|
| -
|
| -The script @file{gdb_buildall.sh} builds @value{GDBN} with flag
|
| -@option{--enable-targets=all} set. This builds @value{GDBN} with all supported
|
| -targets activated. This helps testing @value{GDBN} when doing changes that
|
| -affect more than one architecture and is much faster than using
|
| -@file{gdb_mbuild.sh}.
|
| -
|
| -After building @value{GDBN} the script checks which architectures are
|
| -supported and then switches the current architecture to each of those to get
|
| -information about the architecture. The test results are stored in log files
|
| -in the directory the script was called from.
|
| -
|
| -@include observer.texi
|
| -
|
| -@node GNU Free Documentation License
|
| -@appendix GNU Free Documentation License
|
| -@include fdl.texi
|
| -
|
| -@node Concept Index
|
| -@unnumbered Concept Index
|
| -
|
| -@printindex cp
|
| -
|
| -@node Function and Variable Index
|
| -@unnumbered Function and Variable Index
|
| -
|
| -@printindex fn
|
| -
|
| -@bye
|
|
|
Chromium Code Reviews
Issue 124383005:
GDB 7.6.50 (Closed)
Base URL: http://git.chromium.org/native_client/nacl-gdb.git@upstream