Official Discord server: https://discord.gg/7WB6Ur3

AUR package (provides mlibc-gcc): https://aur.archlinux.org/packages/mlibc

Ports to new OSes are welcome. To port mlibc to another OS, the following changes need to be made:

1. Add new sysdeps/ subdirectory sysdeps/some-new-os/ and a meson.build to compile it. Integreate sysdeps/some-new-os/meson.build into the toplevel meson.build.
2. Create ABI headers in abis/some-new-os/. Add symlinks in sysdeps/some-new-os/include/abi-bits to your ABI headers. Look at existing ports to figure out the ABI headers required for the options enabled by sysdeps/some-new-os/meson.build.
3. In sysdeps/some-new-os/, add code to implement (a subset of) the functions from options/internal/include/mlibc/internal-sysdeps.hpp. Which subset you need depends on the options that sysdeps/some-new-os/meson.build enables.

We recommend that new ports do not build from master as we occasionally make internal changes that cause out-of-tree sysdeps to break. Instead we recommend you pin a specific release (or commit), or to upstream your changes to this repository so that we can build them on our CI and thus any breakages will be fixed by us in-tree.

The following custom meson options are accepted, in addition to the built-in options. The options below are booleans which default to false (see meson_options.txt).

• headers_only: Only install headers; don't build libc.so or ld.so.
• mlibc_no_headers: Don't install headers; only build libc.so and ld.so.
• build_tests: Build the test suite (see below).
• disable_x_option: Disable x component of mlibc functionality. See meson_options.txt for a full list of possible values for x. This may be used to e.g disable POSIX and glibc extensions.
• linux_kernel_headers: Allows for directing mlibc to installed linux headers. These can be obtained easily, placed in a directory and this option set to the corresponding path. This is required if the linux option is enabled, i.e. when the linux option is not disabled.

The type of library to be built (static, shared, or both) is controlled by meson's default_library option. Passing -Ddefault_library=static effectively disables the dynamic linker.

We also support building with -Db_sanitize=undefined to use UBSan inside mlibc. Note that this does not enable UBSan for external applications which link against libc.so, but it can be useful during development to detect internal bugs (e.g when adding new sysdeps).

The mlibc test suite can be run under a Linux host. To do this, first install a set of kernel headers (as described here), then run from the project root:

meson setup -Dbuild_tests=true -Dlinux_kernel_headers=/path/to/kernel/headers/include build

This will create a build directory. Then, cd build and run the tests (showing output) with:

meson test -v