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@@ -21,3 +21,106 @@ bootstrapping, and Linux distributions built on musl can be found on the project website: http://www.musl-libc.org/ + +Quick Installation Guide for musl libc +====================================== + +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. + +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. + + +Build Prerequisites +------------------- + +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 a minimal subset of "GNU C" +extensions consisting mainly of gcc-style inline assembly, weak +aliases, hidden visibility, and stand-alone assembly source files. + +GCC, LLVM/clang, Firm/cparser, and PCC have all successfully built +musl, but GCC is the most widely used/tested. Recent compiler (and +binutils) versions should be used if possible since some older +versions have bugs which affect musl. + +The system used to build musl does not need to be Linux-based, nor do +the Linux kernel headers need to be available. + + + +Supported Targets +----------------- + +musl can be built for the following CPU instruction set architecture +and ABI combinations: + +* i386 + * Minimum CPU model is actually 80486 unless kernel emulation of + the `cmpxchg` instruction is added + +* x86_64 + * ILP32 ABI (x32) is available as a separate arch but is still + experimental + +* ARM + * EABI, standard or hard-float VFP variant + * Little-endian default; big-endian variants also supported + * Compiler toolchains only support armv4t and later + +* AArch64 + * Little-endian default; big-endian variants also supported + +* MIPS + * ABI is o32, fp32/fpxx (except on r6 which is fp64) + * 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 + * MIPS32r6, an incompatible ISA, is supported as a variant "mipsr6" + +* MIPS64 + * ABI is n64 (LP64) or n32 (ILP32) + * 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 + +* PowerPC + * 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 + +* PowerPC64 + * Both little and big endian variants are supported + * Compiler toolchain must provide 64-bit long double, not IBM + double-double or IEEE quad + * Compiler toolchain must use the new (ELFv2) ABI regardless of + whether it is for little or big endian + +* S390X (64-bit S390) + +* SuperH (SH) + * Standard ELF ABI or FDPIC ABI (shared-text without MMU) + * Little-endian by default; big-endian variant also supported + * Full FPU ABI or soft-float ABI is supported, but the + single-precision-only FPU ABI is not + +* Microblaze + * Big-endian default; little-endian variants also supported + * Soft-float + * Requires support for lwx/swx instructions + +* OpenRISC 1000 (or1k) + +* RISC-V 64 + * Little endian + * Hard, soft, and hard-single/soft-double floating point ABIs + * Standard ELF; no shared-text NOMMU support |