Toolchain/Linux - Build a Linux sysroot (Linux headers + libc)

[ziuziakowska]

For building executables to run on Linux, a toolchain on its own does not suffice. The program will need a system C library (libc) to link against, which in turn requires headers from Linux itself (for types and structures, syscall numbers, etc). This is known as a "sysroot".

[ziuziakowska]

A cheribuild command that performs all these steps is
./cheribuild.py busybox-linux-riscv64-purecap -d --cheri-std093-sdk-root <path to toolchain build> -j$(nproc), without -purecap this performs the same build but for Integer mode. We would probably want both.

[engdoreis]

I have a nix derivation to build muslc, now I need to combine it with the derivation that builds llvm.

[engdoreis]

I've created a stdenv to combine muslc and clang, later I fund that the linux headers from the linux repository is also needed.

[engdoreis]

Linux headers included in the toolchain, however busybox fails to link.
It needs compiler-rt libs.

[engdoreis]

Trying to build compiler-rt with llvm by adding (cmakeFeature "LLVM_ENABLE_RUNTIMES" "compiler-rt"), as opposed to cheribuild that build both separately.