X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=INSTALL;h=2994630a403d6f41f6828d65db85b1ec2db639ec;hb=6119fa32698b6e1f79564c2a30d81b179f48c156;hp=f39d627413940dc9c8e71fc7d5361e34972caf32;hpb=a23563024fc75a85af955ca203e26c52f939b414;p=musl diff --git a/INSTALL b/INSTALL index f39d6274..2994630a 100644 --- a/INSTALL +++ b/INSTALL @@ -1,148 +1,177 @@ -==== Installing musl ==== +Quick Installation Guide for musl libc +====================================== -musl may be installed either as an alternate C library alongside the -existing libraries on a system, or as the primary C library for a new -or existing musl-based system. +There are many different ways to install musl depending on your usage +case. This document covers only the build and installation of musl by +itself, which is useful for upgrading an existing musl-based system or +compiler toolchain, or for using the provided musl-gcc wrapper with an +existing non-musl-based compiler. -First, some prerequisites: +Building complete native or cross-compiler toolchains is outside the +scope of this INSTALL file. More information can be found on the musl +website and community wiki. -- A C99 compiler with gcc-style inline assembly support, support for - weak aliases, and support for building stand-alone assembly files. - gcc 3.x and 4.x are known to work. pcc and LLVM/clang may work but - are untested, and pcc is known to have some bugs. -- GNU make +Build Prerequisites +------------------- -- Linux, preferably 2.6.22 or later. Older versions are known to have - serious bugs that will make some interfaces non-conformant, but if - you don't need threads or POSIX 2008 features, even 2.4 is probably - okay. +The only build-time prerequisites for musl are GNU Make and a +freestanding C99 compiler toolchain targeting the desired instruction +set architecture and ABI, with support for gcc-style inline assembly, +weak aliases, and stand-alone assembly source files. -- A supported CPU architecture (currently i386, x86_64, or arm). +The system used to build musl does not need to be Linux-based, nor do +the Linux kernel headers need to be available. -- If you want to use dynamic linking, it's recommended that you have - permissions to write to /lib and /etc. Otherwise your binaries will - have to use a nonstandard dynamic linker path. +If support for dynamic linking is desired, some further requirements +are placed on the compiler and linker. In particular, the linker must +support the -Bsymbolic-functions option. +At present, GCC 4.6 or later is the recommended compiler for building +musl. Any earlier version of GCC with full C99 support should also +work, but may be subject to minor floating point conformance issues on +i386 targets. Sufficiently recent versions of PCC and LLVM/clang are +also believed to work, but have not been tested as heavily; prior to +Fall 2012, both had known bugs that affected musl. Firm/cparser is +also believed to work but lacks support for producing shared +libraries. GCC 4.9.0 is known to have a serious bug (#61144) which +affects musl and is not supported. -== Option 1: Installing musl as an alternate C library == -In this setup, musl and any third-party libraries linked to musl will -reside under an alternate prefix such as /usr/local/musl or /opt/musl. -A wrapper script for gcc, called musl-gcc, can be used in place of gcc -to compile and link programs and libraries against musl. +Supported Targets +----------------- -To install musl as an alternate libc, follow these steps: +musl can be built for the following CPU instruction set architecture +and ABI combinations: -1. Configure musl's build with a command similar to: - ./configure --prefix=/usr/local/musl --exec-prefix=/usr/local - Refer to ./configure --help for details on other options. You may - change the install prefix if you like, but DO NOT set it to a - location that contains your existing libraries based on another - libc such as glibc or uClibc. If you do not intend to use dynamic - linking, you may disable it at this point via --disable-shared and - cut the build time in half. If you wish to use dynamic linking but - do not have permissions to write to /lib, you will need to set an - alternate dynamic linker location via --syslibdir. +* i386 + * Minimum CPU model is actually 80486 unless kernel emulation of + the `cmpxchg` instruction is added -2. Run "make". Parallel build is fully supported, so you can instead - use "make -j3" or so on SMP systems if you like. +* x86_64 -3. Run "make install" as a user sufficient privileges to write to the - destination. +* ARM + * EABI, standard or hard-float VFP variant + * Little-endian default; big-endian variants also supported + * Compiler toolchains only support armv4t and later -4. Create a file named /etc/ld-musl-$ARCH.path (where $ARCH is - replaced by i386, x86_64, etc. as appropriate) containing the - correct colon-delimited search path for where you intend to install - musl-linked shared library files. If this file is missing, musl - will search the standard path, and you will encounter problems when - it attempts to load libraries linked against your host libc. Note - that this step can be skipped if you disabled dynamic linking. +* MIPS + * ABI is o32 + * Big-endian default; little-endian variants also supported + * Default ABI variant uses FPU registers; alternate soft-float ABI + that does not use FPU registers or instructions is available + * MIPS2 or later, or kernel emulation of ll/sc (standard in Linux) + is required -After installing, you can use musl via the musl-gcc wrapper. For -example: +* PowerPC + * Only 32-bit is supported + * Compiler toolchain must provide 64-bit long double, not IBM + double-double or IEEE quad + * For dynamic linking, compiler toolchain must be configured for + "secure PLT" variant -cat > hello.c < -int main() -{ - printf("hello, world!\n"); - return 0; -} -EOF -musl-gcc hello.c -./a.out +* Microblaze + * Big-endian default; little-endian variants also supported + * Soft-float + * Requires support for lwx/swx instructions -To configure autoconf-based program to compile and link against musl, -you may wish to use: +The following additional targets are available for build, but may not +work correctly and may not yet have ABI stability: -CC="musl-gcc -D_GNU_SOURCE" ./configure ... +* SuperH (SH) + * Little-endian by default; big-engian variant also supported + * Full FPU ABI or soft-float ABI is supported, but the + single-precision-only FPU ABI is not supported (musl always + requires IEEE single and double to be supported) -Correctly-written build systems should not need -D_GNU_SOURCE as part -of $CC, but many programs do not use feature-test macros correctly and -simply assume the compiler will automatically give them the kitchen -sink, so the above command is an easy workaround. +* x32 (x86_64 ILP32 ABI) -You will probably also want to use --prefix when building libraries to -ensure that they are installed under the musl prefix and not in the -main host system library directories. -Finally, it's worth noting that musl's include and lib directories in -the build tree are setup to be usable without installation, if -necessary. Just modify the the paths in the spec file used by musl-gcc -(it's located at $prefix/lib/musl-gcc.specs) to point to the -source/build tree. +Build and Installation Procedure +-------------------------------- + +To build and install musl: + +1. Run the provided configure script from the top-level source + directory, passing on its command line any desired options. + +2. Run "make" to compile. + +3. Run "make install" with appropriate privileges to write to the + target locations. +The configure script attempts to determine automatically the correct +target architecture based on the compiler being used. For some +compilers, this may not be possible. If detection fails or selects the +wrong architecture, you can provide an explicit selection on the +configure command line. -== Option 2: Installing musl as the primary C library == +By default, configure installs to a prefix of "/usr/local/musl". This +differs from the behavior of most configure scripts, and is chosen +specifically to avoid clashing with libraries already present on the +system. DO NOT set the prefix to "/usr", "/usr/local", or "/" unless +you're upgrading libc on an existing musl-based system. Doing so will +break your existing system when you run "make install" and it may be +difficult to recover. -In this setup, you will need an existing compiler/toolchain. It -shouldnt matter whether it was configured for glibc, uClibc, musl, or -something else entirely, but sometimes gcc can be uncooperative, -especially if the system distributor has built gcc with strange -options. It probably makes the most sense to perform the following -steps inside a chroot setup or on a virtualized machine with the -filesystem containing just a minimal toolchain. -WARNING: DO NOT DO THIS ON AN EXISTING SYSTEM UNLESS YOU REALLY WANT -TO CONVERT IT TO BE A MUSL-BASED SYSTEM!! -1. If you are just upgrading an existing version of musl, you can skip - step 1 entirely. Otherwise, move the existing include and lib - directories on your system out of the way. Unless all the binaries - you will need are static-linked, you should edit /etc/ld.so.conf - (or equivalent) and put the new locations of your old libraries in - the search path before you move them, or your system will break - badly and you will not be able to continue. +Notes on Dynamic Linking +------------------------ -2. Configure musl's build with a command similar to: - ./configure --prefix=/usr --disable-gcc-wrapper - Refer to ./configure --help for details on other options. +If dynamic linking is enabled, one file needs to be installed outside +of the installation prefix: /lib/ld-musl-$ARCH.so.1. This is the +dynamic linker. Its pathname is hard-coded into all dynamic-linked +programs, so for the sake of being able to share binaries between +systems, a consistent location should be used everywhere. Note that +the same applies to glibc and its dynamic linker, which is named +/lib/ld-linux.so.2 on i386 systems. -3. Run "make" to compile musl. +If for some reason it is impossible to install the dynamic linker in +its standard location (for example, if you are installing without root +privileges), the --syslibdir option to configure can be used to +provide a different location -4. Run "make install" with appropriate privileges. +At runtime, the dynamic linker needs to know the paths to search for +shared libraries. You should create a text file named +/etc/ld-musl-$ARCH.path (where $ARCH matches the architecture name +used in the dynamic linker) containing a list of directories where you +want the dynamic linker to search for shared libraries, separated by +colons or newlines. If the dynamic linker has been installed in a +non-default location, the path file also needs to reside at that +location (../etc relative to the chosen syslibdir). -5. If you are using gcc and wish to use dynamic linking, find the gcc - directory containing libgcc.a (it should be something like - /usr/lib/gcc/i486-linux-gnu/4.3.5, with the arch and version - possibly different) and look for a specs file there. If none - exists, use "gcc -dumpspecs > specs" to generate a specs file. Find - the dynamic linker (/lib/ld-linux.so.2 or similar) and change it to - "/lib/ld-musl-$ARCH.so.1" (with $ARCH replaced by your CPU arch). +If you do not intend to use dynamic linking, you may disable it by +passing --disable-shared to configure; this also cuts the build time +in half. -At this point, musl should be the default libc. Compile a small test -program with gcc and verify (using readelf -a or objdump -x) that the -dynamic linker (program interpreter) is /lib/ld-musl-$ARCH.so.1. If -you're using static linking only, you might instead check the symbols -and look for anything suspicious that would indicate your old glibc or -uClibc was used. -When building programs against musl, you may still want to ensure the -appropriate feature test macros get defined, as in: -CC="gcc -D_GNU_SOURCE" ./configure ... +Checking for Successful Installation +------------------------------------ +After installing, you should be able to use musl via the musl-gcc +wrapper. For example: + +cat > hello.c < +int main() +{ + printf("hello, world!\n"); + return 0; +} +EOF +/usr/local/musl/bin/musl-gcc hello.c +./a.out + +To configure autoconf-based program to compile and link against musl, +set the CC variable to musl-gcc when running configure, as in: + +CC=musl-gcc ./configure ... + +You will probably also want to use --prefix when building libraries to +ensure that they are installed under the musl prefix and not in the +main host system library directories.