http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51181
--- Comment #2 from joseph at codesourcery dot com <joseph at codesourcery dot com> 2011-11-17 21:06:54 UTC --- FWIW, classic m68k has compare-and-swap, while ColdFire Linux uses kernel helpers (available in both vDSO and syscall forms; the syscall forms are probably rather easier to use from libgcc than the vDSO is).