Awesome
CMLFS - Clang Musl Linux From Scratch
CMLFS can either mean "Clang-built Musl Linux from Scratch" or "Clang MLFS". It started as a hobby to see if a Linux system can be built with clang as primary toolchain and GCC as secondary (for packages that cannot be built with clang). This is based on Linux From Scratch and my previous work MLFS. Big thanks to Chimera-Linux that had patches that fixed a lot of issues.
DISCLAIMER
Use at you own risk. This builds a Unix-like system that may not be stable enough as a 'daily driver' for most users. Security-hardening of the built system is beyound the scope of this project. This repo started as means to backup and archive my work.
Getting Started
The master branch may be unstable when I am working on upgrading CMLFS.
To build this project, pick a branch other than master OR choose a tag. Each branch & tag are based on the LLVM version. As of this writing, llvm-15.0.6 is stable. Older branches maybe incomplete or unstable (may not compile).
When I have time later, I will write a more thorough introduction for users new to CMLFS.
Specification
<ul> <li>C Runtime Library (system libc): Musl </li> <li>Default C Compiler: clang (LLVM)</li> <li>Default C++ compiler: clang++ (LLVM)</li> <li>Default linker: lld (LLVM)</li> <li>Default binary tools: elftoolchain</li> <li>Secondary C Compiler: GCC</li> <li>Secondary C++ compiler: GCC</li> <li>Secondary binary tools: GNU Binutils & LLVM</li> <li>Secondary linker(s): bfd, gold</li> <li>C++ standard library: libcxx (LLVM)</li> <li>C++ ABI library: libcxxabi (LLVM)</li> <li>Unwinding Library: libunwind (LLVM)</li> <li>Init system: skarnet's S6 & S6-rc</li> <li>Device manager: Udev </li> <li>TLS Implementaion: LibreSSL</li> <li>Secondary TLS Implementaion: OpenSSL</li> <li>System Shell: Bash </li> <li>System Gettext: gettext-tiny</li> <li>Curses Library: netbsd-curses </li> </ul>Supported Architectures
<ul> <li>AMD64/x86_64: Toolchains and final system build sucessfully (musl & glibc hosts) .</li> <li>i686: Pending</li> <li>AARCH64/ARM64: Pending</li> <li>ARMV7L: Pending</li> </ul>Goals
<ul> <li> [x] Build a toolchain (llvmtools) with LLVM+stage1_clang but without GCC</li> <li> [x] Build final root filesystem with LLVM</li> <li> [x] Set default linker as lld(LLVM)</li> <li> [x] Set default C++ standard library as libcxx(LLVM)</li> <li> [x] Set default C++ ABI library as libcxxabi(LLVM)</li> <li> [x] Set default stack unwinding library as libunwind(LLVM)</li> <li> [x] Eliminate dependacy on GCC's libgcc_s</li> <li> [x] Build GCC as a secondary systen compiler. </li> <li> [x] Build toolchain (llvmtools) with GCC as secondary compiler</li> <li> [x] Merge cross-tools build with cgnutools </li> <li> [x] Build successfully on a Glibc host </li> <li> [x] Build final system without GCC </li> <li> [x] Replace binutils with elftoolchain </li> <li> [ ] Reduce LLVM size & build time for cgnutools and llvmtools </li> <li> [ ] Create initramfs with busybox & mdev </li> <li> [ ] Build on aarch64</li> </ul>Host System Requirements
<ul> <li>CMake</li> <li>Ninja/Samurai</li> <li>wget/cURL</li> </ul>Required Base Development tools (may refer to LFS)
<ul> <li>bash 3.2 (/bin/sh should be a symbolic or hard link to bash) </li> <li>binutils 2.25 </li> <li>bison 2.7 (/usr/bin/yacc should be a link to bison or small script that executes bison) </li> <li>bzip2 1.0.4 </li> <li>coreutils 6.9 </li> <li>diffutils 2.8.1 </li> <li>findutils 4.2.31 </li> <li>gawk 4.0.1 (/usr/bin/awk should be a link to gawk) </li> <li>GCC 6.2 (including the C++ compiler, g++) </li> <li>Glibc 2.11 / Musl Libc 1.20 </li> <li>Grep 2.5.1a </li> <li>gzip 1.3.12 </li> <li>linux kernel 3.2 (not sure if it matters, as most distros are running 4.x/5.x kernels</li> <li>m4 1.4.10</li> <li>make 4.0 </li> <li>patch 2.5.4 </li> <li>Python 3.4 </li> <li>sed 4.1.5 </li> <li>tar 1.22 </li> <li>texinfo 4.7 </li> <li>xz 5.0.0 </li> </ul> * (if hostdistro is MLFS/LFS, then all development packages are installed)Current Method
Build 'cross-tools' with Mussel to cross-compile a stage0 LLVM+clang. This stage0 clang will still link to libgcc_s [in cgnutools] but will later be used to build a stage1 clang free of libbgcc_s. The goal is to build clang+friends with clang and not GCC.
- Some packages can be built once to be used by the toolchain [llvmtools] and the final system, but will be built twice to make it easy to implement a package managment system [which is outside the scope of this project].