How to perform atomic operations on Linux that work on x86, arm, GCC and icc?

Projects are using this:

http://packages.debian.org/source/sid/libatomic-ops

If you want simple operations such as CAS, can't you just just use the arch-specific implementations out of the kernel, and do arch checks in user-space with autotools/cmake? As far as licensing goes, although the kernel is GPL, I think it's arguable that the inline assembly for these operations is provided by Intel/AMD, not that the kernel has a license on them. They just happen to be in an easily accessible form in the kernel source.

Recent standards (from 2011) of C & C++ now specify atomic operations:

• C11: stdatomic.h
• C++11: std::atomic

Regardless, your platform or compiler may not support these newer headers & features.