standalone_musl

This repository implements a musl libc fork that provides enhanced glibc compatibility and facilitates the creation of "semi-static" binaries. This is currently based on musl v1.2.5 (@0784374d56).

Goals:

• Enable the creation of "semi-static" binaries, i.e. statically linked
  binaries that integrate the dynamic loader, allowing the use of
  dlopen(), dlsym(), etc. for use cases that require this.
  E.g. loading graphics drivers for Vulkan, CUDA, OpenXR, etc. support.
• Provide ABI and API compatibility with glibc, as far as necessary to
  support the first goal.
• Dynamic replacement of system library loads by statically linking our
  own libraries and providing their symbols.
  E.g. dynamically replacing the load of libgcc_s.so by integrating and
  providing LLVM's libunwind, libcxxabi and compiler-rt.

Non-Goals:

• Upstreaming: since all of these changes are very invasive and in many
  ways contrary to what musl is doing, upstreaming any of this is very
  much out of the question and generally pointless.
  Note that I will try to keep of with musl development and rebase on
  top of future release versions.

Limitations and other info:

• GNU indirect function support ("ifunc") is not fully supported. There
  is some very limited support, but this should generally be avoided.
  System libraries that make use of this can be replaced (see goal #3).
• Building dynamic binaries is currently broken.
• semi-static binaries must link these in the specified order:
  ldso_rcrt1.o crti.o crtn.o
• semi-static binaries must use the entry point _dlstart.
  Linker option: -e _dlstart
• semi-static binaries must link with -lc_ldso
• semi-static binaries must use --whole-archive linking for making
  integrated libraries and their symbols available to dynamically
  loaded libraries.
  Specifically, this needs whole archive linking for:
  -lc, -lc_ldso and the clang/compiler-rt libclang_rt.builtins.a
  Additionally, for C++: -lc++ -lc++abi -lunwind

Status:

• When integrating additional system libraries, this is currently able
  to load and actually make use of NVIDIA drivers for CUDA and Vulkan,
  AMD AMDVLK drivers for use with Vulkan, and Mesa RADV drivers for
  use with Vulkan.
  Other drivers may also work, but these are the ones I've currently
  tested. PRs to make other drivers work are welcome :)

On top of musl, this repository also integrates the following libraries to enhance and provide additional glibc compatibility:

• libgcompat (v1.1.0): https://git.adelielinux.org/adelie/gcompat
• libucontext (@be80075e95): https://github.com/kaniini/libucontext
• libbsd (v0.12.2): https://libbsd.freedesktop.org/wiki
  (arc4random support only)
  Please check the respective sub-folders for additional licensing terms.

NOTE: A full toolchain integrating this will be released soon(tm).

Original README

musl libc

musl, pronounced like the word "mussel", is an MIT-licensed implementation of the standard C library targetting the Linux syscall API, suitable for use in a wide range of deployment environments. musl offers efficient static and dynamic linking support, lightweight code and low runtime overhead, strong fail-safe guarantees under correct usage, and correctness in the sense of standards conformance and safety. musl is built on the principle that these goals are best achieved through simple code that is easy to understand and maintain.

The 1.1 release series for musl features coverage for all interfaces defined in ISO C99 and POSIX 2008 base, along with a number of non-standardized interfaces for compatibility with Linux, BSD, and glibc functionality.

For basic installation instructions, see the included INSTALL file. Information on full musl-targeted compiler toolchains, system bootstrapping, and Linux distributions built on musl can be found on the project website:

http://www.musl-libc.org/