Cross compile Linux for ARM using LLVM/clang on Arch Linux

The LLVMLinux team made quite some progress in enabling LLVM/clang to build the Linux kernel. There has also been a talk at the Collaboration Summit 2015 in Santa Rosa (slides). So I thought, give it a try and compile a kernel for my ARM based board of choice. The upstream kernel.org Linux kernel is not yet ready to be built using LLVM/clang, some patches are still required. Therefor I used the kernel from the LLVMLinux git server.

The nice thing about LLVM/clang is that it supports multiple targets. The binaries provided by the Arch repositories support several ARM targets:

$ pacman -S clang
...
$ llc --version
LLVM (http://llvm.org/):
 LLVM version 3.5.1
 Optimized build.
 Built Jan 14 2015 (03:18:15).
 Default target: x86_64-unknown-linux-gnu
 Host CPU: core-avx-i

 Registered Targets:
 aarch64 - AArch64 (little endian)
 aarch64_be - AArch64 (big endian)
 arm - ARM
 arm64 - AArch64 (little endian)
 arm64_be - AArch64 (big endian)
 armeb - ARM (big endian)
...

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