Update chrome/nacl.gypi to fix chromeos build

chrome/nacl.gypi

 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'target_defaults': {
     'variables': {
       'nacl_target': 0,
     },
     'target_conditions': [
@@ skipping 218 matching lines @@
           # would be if gyp were to really build properly for the host.
           # TODO(bradnelson): Clean up with proper cross support.
           'conditions': [
             ['host_arch=="x64"', {
               'cflags/': [['exclude', '-m.*']],
               'ldflags/': [['exclude', '-m.*']],
             }],
           ],
         },
         {
-          'target_name': 'nacl_helper_bootstrap_raw',
-          'type': 'executable',
+          'target_name': 'nacl_helper_bootstrap_lib',

[Roland McGrath, 2011/09/07 17:21:17]

This is a library not actually being used for anything.
I guess you have it here just as the way to get the source file compiled, and I
have no idea what 'hard_dependency' does.  This needs some comments.

If this is indeed the best or only way to get the source file compiled, then it
would be cleaner to actually use the singleton library in the link.  For that,
you'd use the library as the inputs list for the linking rule, and use the
--whole-archive option before the inputs and --no-whole-archive after the inputs
list.

[Brad Chen, 2011/09/07 19:05:40]

Done.

+          'type': 'static_library',
+          'hard_depencency': 1,
           'include_dirs': [
             '..',
           ],
           'sources': [
             'nacl/nacl_helper_bootstrap_linux.c',

[Roland McGrath, 2011/09/07 17:21:17]

Putting the linker script here was on the recommendation of Brad Nelson.  I
think you should consult with him before removing it.

[Brad Chen, 2011/09/07 19:05:40]

The linker script is now an input dependency of the executable (not the
library), which seems like the right place for it.
On 2011/09/07 17:21:17, Roland McGrath wrote:

-            # We list the linker script here for documentation purposes.
-            # But even this doesn't make gyp treat it as a dependency,
-            # so incremental builds won't relink when the script changes.
-            # TODO(bradnelson): Fix the dependency handling.
-            'nacl/nacl_helper_bootstrap_linux.x',
           ],
           'cflags': [
             # The tiny standalone bootstrap program is incompatible with
             # -fstack-protector, which might be on by default.  That switch
             # requires using the standard libc startup code, which we do not.
             '-fno-stack-protector',
             # We don't want to compile it PIC (or its cousin PIE), because
             # it goes at an absolute address anyway, and because any kind
             # of PIC complicates life for the x86-32 assembly code.  We
             # append -fno-* flags here instead of using a 'cflags!' stanza
             # to remove -f* flags, just in case some system's compiler
             # defaults to using PIC for everything.
             '-fno-pic', '-fno-PIC',
             '-fno-pie', '-fno-PIE',
           ],
-          'link_settings': {
-            'ldflags': [
-              # TODO(bradchen): Delete the -B argument when Gold is verified
-              # to produce good results with our custom linker script.
-              # Until then use ld.bfd.
-              '-B', '<(PRODUCT_DIR)/../../tools/ld_bfd',
-              # This programs is (almost) entirely standalone.  It has
-              # its own startup code, so no crt1.o for it.  It is
-              # statically linked, and on x86 it actually does not use
-              # libc at all.  However, on ARM it needs a few (safe)
-              # things from libc, so we don't use '-nostdlib' here.
-              '-static', '-nostartfiles',
-              # Link with our custom linker script to get out special layout.
-              '-Wl,--script=<(PRODUCT_DIR)/../../chrome/nacl/nacl_helper_bootstrap_linux.x',
-              # On x86-64, the default page size with some
-              # linkers is 2M rather than the real Linux page
-              # size of 4K.  A larger page size is incompatible
-              # with our custom linker script's special layout.
-              '-Wl,-z,max-page-size=0x1000',
-            ],
-          },
+        },
+        {
+          'target_name': 'nacl_helper_bootstrap_raw',
+          'type': 'none',
+          'dependencies': [
+            'nacl_helper_bootstrap_lib',
+          ],
+          'actions': [
+            {
+              'action_name': 'link_with_ld_bfd',
+              'variables': {
+                # We list the linker script here for documentation purposes.
+                # But even this doesn't make gyp treat it as a dependency,
+                # so incremental builds won't relink when the script changes.
+                # TODO(bradnelson): Fix the dependency handling.

[Roland McGrath, 2011/09/07 17:21:17]

This comment doesn't make any sense here.

[Brad Chen, 2011/09/07 19:05:40]

Removed
On 2011/09/07 17:21:17, Roland McGrath wrote:

+                'nacl_bootstrap_linker_script': './nacl/nacl_helper_bootstrap_linux.x',
+              },
+              'inputs': [
+                '<(PRODUCT_DIR)/obj.target/nacl_helper_bootstrap_lib/chrome/nacl/nacl_helper_bootstrap_linux.o',

[Evan Martin, 2011/09/07 17:14:00]

This is hardcoding a private build path.  It may work in some build
configuration but it may not work for all (like in cross-compile) situations. 
(Certainly not on ninja, where the paths are completely different.)

Taking a step back, I think all of this code would likely be easier if you just
made a shell script that does all the work you need.  gyp is designed such that
it is intentionally stupid, making the common case easy but the slightly
uncommon case (like this) very hard to express in gyp rules.

[Brad Chen, 2011/09/07 19:05:40]

With help from Brad Nelson I think I figured out how to avoid referring to
obj.target. PTAL.

On 2011/09/07 17:14:00, Evan Martin wrote:

+              ],
+              'outputs': [
+                '<(PRODUCT_DIR)/nacl_helper_bootstrap_raw',
+              ],
+              'message': 'Linking nacl_helper_bootstrap_raw',
+              'conditions': [
+                ['target_arch=="x64"', {
+                  'variables': {
+                    'linker_emulation': 'elf_x86_64',
+                  }
+                }],
+                ['target_arch=="ia32"', {
+                  'variables': {
+                    'linker_emulation': 'elf_i386',
+                  }
+                }],
+                ['target_arch=="arm"', {
+                  'variables': {
+                    'linker_emulation': 'arm',

[Roland McGrath, 2011/09/07 17:21:17]

This should be 'armelf_linux_eabi'.

[Brad Chen, 2011/09/07 19:05:40]

Done.

+                  }
+                }],
+              ],
+              'action': ['../tools/ld_bfd/ld',
+                         '-m', '<(linker_emulation)',
+                         # This program is (almost) entirely standalone.  It
+                         # has its own startup code, so no crt1.o for it.  It is
+                         # statically linked, and on x86 it does not use
+                         # libc at all.  However, on ARM it needs a few (safe)

[Roland McGrath, 2011/09/07 17:21:17]

This comment doesn't make sense here.  There is no -stdlib option to the linker,
nor any implicit startfiles or libraries we are avoiding (we're just not adding
any).

[Brad Chen, 2011/09/07 19:05:40]

I've revised it, removing the -nostdlib', so that it makes more sense.
On 2011/09/07 17:21:17, Roland McGrath wrote:

+                         # things from libc, so we don't use '-nostdlib' here.
+                         '-static',
+                         '-o', '<@(_outputs)',
+                         # Link with custom linker script for special layout.
+                         '--script=<(nacl_bootstrap_linker_script)',
+                         # On x86-64, the default page size with some
+                         # linkers is 2M rather than the real Linux page
+                         # size of 4K.  A larger page size is incompatible
+                         # with our custom linker script's special layout.
+                         '-z', 'max-page-size=0x1000',
+                         '<@(_inputs)',

[Roland McGrath, 2011/09/07 17:21:17]

For ARM it's necessary to add a '-lc' argument after the inputs.  That argument
is harmless for x86, though unnecessary.

[Brad Chen, 2011/09/07 19:05:40]

Done.

+                       ],
+            }
+          ],
         },
         {
           'target_name': 'nacl_helper_bootstrap',
           'dependencies': [
             'nacl_helper_bootstrap_raw',
             'nacl_helper_bootstrap_munge_phdr#host',
           ],
           'type': 'none',
           'actions': [{
               'action_name': 'munge_phdr',
               'inputs': ['nacl/nacl_helper_bootstrap_munge_phdr.py',
                          '<(PRODUCT_DIR)/nacl_helper_bootstrap_munge_phdr',
                          '<(PRODUCT_DIR)/nacl_helper_bootstrap_raw'],
               'outputs': ['<(PRODUCT_DIR)/nacl_helper_bootstrap'],
               'message': 'Munging ELF program header',
               'action': ['python', '<@(_inputs)', '<@(_outputs)']
             }],
-          }
+          },
       ],
     }],
   ],
 }