fusl/INSTALL - Issue 1574103002: Remove cruft from fusl

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Issue 1574103002: Remove cruft from fusl (Closed) Base URL: https://github.com/domokit/mojo.git@master

Patch Set: Created 4 years, 11 months ago

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1

2 Quick Installation Guide for musl libc

3 ======================================

4

5 There are many different ways to install musl depending on your usage

6 case. This document covers only the build and installation of musl by

7 itself, which is useful for upgrading an existing musl-based system or

8 compiler toolchain, or for using the provided musl-gcc wrapper with an

9 existing non-musl-based compiler.

10

11 Building complete native or cross-compiler toolchains is outside the

12 scope of this INSTALL file. More information can be found on the musl

13 website and community wiki.

14

15

16 Build Prerequisites

17 -------------------

18

19 The only build-time prerequisites for musl are GNU Make and a

20 freestanding C99 compiler toolchain targeting the desired instruction

21 set architecture and ABI, with support for gcc-style inline assembly,

22 weak aliases, and stand-alone assembly source files.

23

24 The system used to build musl does not need to be Linux-based, nor do

25 the Linux kernel headers need to be available.

26

27 If support for dynamic linking is desired, some further requirements

28 are placed on the compiler and linker. In particular, the linker must

29 support the -Bsymbolic-functions option.

30

31 At present, GCC 4.6 or later is the recommended compiler for building

32 musl. Any earlier version of GCC with full C99 support should also

33 work, but may be subject to minor floating point conformance issues on

34 i386 targets. Sufficiently recent versions of PCC and LLVM/clang are

35 also believed to work, but have not been tested as heavily; prior to

36 Fall 2012, both had known bugs that affected musl. Firm/cparser is

37 also believed to work but lacks support for producing shared

38 libraries. GCC 4.9.0 and 4.9.1 are known to have a serious bug

39 (#61144) which affects musl. Beginning with version 1.1.4 musl

40 attempts to work around the bug, but these compiler versions are still

41 considered unstable and unsupported.

42

43

44

45 Supported Targets

46 -----------------

47

48 musl can be built for the following CPU instruction set architecture

49 and ABI combinations:

50

51 * i386

52 * Minimum CPU model is actually 80486 unless kernel emulation of

53 the `cmpxchg` instruction is added

54

55 * x86_64

56

57 * ARM

58 * EABI, standard or hard-float VFP variant

59 * Little-endian default; big-endian variants also supported

60 * Compiler toolchains only support armv4t and later

61

62 * MIPS

63 * ABI is o32

64 * Big-endian default; little-endian variants also supported

65 * Default ABI variant uses FPU registers; alternate soft-float ABI

66 that does not use FPU registers or instructions is available

67 * MIPS2 or later, or kernel emulation of ll/sc (standard in Linux)

68 is required

69

70 * PowerPC

71 * Only 32-bit is supported

72 * Compiler toolchain must provide 64-bit long double, not IBM

73 double-double or IEEE quad

74 * For dynamic linking, compiler toolchain must be configured for

75 "secure PLT" variant

76

77 * Microblaze

78 * Big-endian default; little-endian variants also supported

79 * Soft-float

80 * Requires support for lwx/swx instructions

81

82 The following additional targets are available for build, but may not

83 work correctly and may not yet have ABI stability:

84

85 * SuperH (SH)

86 * Little-endian by default; big-engian variant also supported

87 * Full FPU ABI or soft-float ABI is supported, but the

88 single-precision-only FPU ABI is not supported (musl always

89 requires IEEE single and double to be supported)

90

91 * x32 (x86_64 ILP32 ABI)

92

93

94

95 Build and Installation Procedure

96 --------------------------------

97

98 To build and install musl:

99

100 1. Run the provided configure script from the top-level source

101 directory, passing on its command line any desired options.

102

103 2. Run "make" to compile.

104

105 3. Run "make install" with appropriate privileges to write to the

106 target locations.

107

108 The configure script attempts to determine automatically the correct

109 target architecture based on the compiler being used. For some

110 compilers, this may not be possible. If detection fails or selects the

111 wrong architecture, you can provide an explicit selection on the

112 configure command line.

113

114 By default, configure installs to a prefix of "/usr/local/musl". This

115 differs from the behavior of most configure scripts, and is chosen

116 specifically to avoid clashing with libraries already present on the

117 system. DO NOT set the prefix to "/usr", "/usr/local", or "/" unless

118 you're upgrading libc on an existing musl-based system. Doing so will

119 break your existing system when you run "make install" and it may be

120 difficult to recover.

121

122

123

124 Notes on Dynamic Linking

125 ------------------------

126

127 If dynamic linking is enabled, one file needs to be installed outside

128 of the installation prefix: /lib/ld-musl-$ARCH.so.1. This is the

129 dynamic linker. Its pathname is hard-coded into all dynamic-linked

130 programs, so for the sake of being able to share binaries between

131 systems, a consistent location should be used everywhere. Note that

132 the same applies to glibc and its dynamic linker, which is named

133 /lib/ld-linux.so.2 on i386 systems.

134

135 If for some reason it is impossible to install the dynamic linker in

136 its standard location (for example, if you are installing without root

137 privileges), the --syslibdir option to configure can be used to

138 provide a different location

139

140 At runtime, the dynamic linker needs to know the paths to search for

141 shared libraries. You should create a text file named

142 /etc/ld-musl-$ARCH.path (where $ARCH matches the architecture name

143 used in the dynamic linker) containing a list of directories where you

144 want the dynamic linker to search for shared libraries, separated by

145 colons or newlines. If the dynamic linker has been installed in a

146 non-default location, the path file also needs to reside at that

147 location (../etc relative to the chosen syslibdir).

148

149 If you do not intend to use dynamic linking, you may disable it by

150 passing --disable-shared to configure; this also cuts the build time

151 in half.

152

153

154

155 Checking for Successful Installation

156 ------------------------------------

157

158 After installing, you should be able to use musl via the musl-gcc

159 wrapper. For example:

160

161 cat > hello.c <<EOF

162 #include <stdio.h>

163 int main()

164 {

165 printf("hello, world!\n");

166 return 0;

167 }

168 EOF

169 /usr/local/musl/bin/musl-gcc hello.c

170 ./a.out

171

172 To configure autoconf-based program to compile and link against musl,

173 set the CC variable to musl-gcc when running configure, as in:

174

175 CC=musl-gcc ./configure ...

176

177 You will probably also want to use --prefix when building libraries to

178 ensure that they are installed under the musl prefix and not in the

179 main host system library directories.

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