64-bit ARM Kernel Gets Closer To Building Under LLVM With Linux 3.18

The 64-bit ARM (AArch64) is closer to building under the LLVM/Clang kernel as an alternative to GCC with the upcoming Linux 3.18 release.

The ARM64 changes for the Linux 3.18 merge window were sent in and include an eBPF JIT compiler for ARM64, a CPU suspend back-end for the PSCI firmware interface, EFI stub improvements, and a code clean-up to allow partially building the kernel with LLVM.

Via the LLVMLinux initiative has been work to build the Linux kernel with Clang for its faster build times, lower memory usage, static analysis capabilities, and for making the kernel's code more portable across compilers. The Clang compiler for x86 and ARM is generally in good shape for being able to build the Linux kernel but there's still patches that haven't yet been mainlined for the kernel side. For more information you can read Building The Linux Kernel With LLVM's Clang Yields Comparable Performance. The good news is that for Linux 3.18 the 64-bit ARM code is closer to being Clang-compatible from mainline.

With the ARM64 pull request are a number of changes by Behan Webster for making the code more Clang-friendly. See the ARM64 patches for more details on all of the 64-bit ARM changes queued up for this next kernel cycle.