musl-cross-make/README.md

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musl-cross-make

This is a quick and simple makefile-based alternative for producing musl-based cross compilers. The current focus is on SH2/J2 Core targets and NOMMU (where PIE or FDPIC is mandatory) since these are not adequately supported by other musl cross-compiler toolchain build systems, but all musl-supported targets are intended to work.

In addition to the build system, musl-cross-make provides a number of patches, including:

  • Updated versions of the musl target patches going into upstream GCC
  • Static-PIE support and optionally defaulting to PIE
  • Fixes for SH-specific bugs and bitrot in GCC
  • Support for J2 Core CPU target in GCC & binutils
  • SH/FDPIC ABI support

Most of these patches are integrated in gcc trunk/binutils master. They should also be usable with Gregor's original musl-cross or other build systems, if desired.

Some functionality (SH/FDPIC, and support for J2 specific features) is presently only available with gcc 5.2.0 and binutils 2.25.1.

Usage

The build system make be configured by providing a config.mak file in the top-level directory. The only mandatory variable is TARGET, which should contain a gcc target tuple (such as sh2eb-linux-musl), but many more options are available. The top-level config.mak.dist file shows examples, and several full configurations are available in presets/*.

For recent gcc versions that need gmp/mpfr/mpc, suitable versions need to be installed in the default library path, or the appropriate --with configure options need to be added to GCC_CONFIG in config.mak so that the gcc configure process can find them.

After setting up config.mak, simply run make. Parallel builds are supported.

The resulting toolchain will be placed ./output by default, or the OUTPUT directory specified in config.mak. It is sysrooted and can be freely moved to a different location.