On 6 May 2011 16:06, Ken Werner <ken.wer...@linaro.org> wrote: > > Currently the GCC ARM backend doesn't provide a pattern to inline 64bit > __sync_* functions but the compiler emits __sync_*_8 function calls [1]. The > libgcc does not provide these symbols via the usual thin wrapper around the > kernel helper [2] because the ARM Linux __kernel_cmpxchg supports 32bit only. > My understanding is that for ARMv7 the GCC backend could be enhanced to inline > the __sync_* functions by using the LDREXD and STREXD instructions. But for > ARMv5 we would still rely on a new kernel helper.
It's a bit tricky with when you want to use the kernel helper for v5t, so we've got to find a way of turning this on only with special knobs and not by default and that's a bit tricky. Think new user space and old kernel and a jump into never-never land. For v7-a you could inline the function using ldrexd / strexd. cheers Ramana > > _______________________________________________ > linaro-dev mailing list > linaro-dev@lists.linaro.org > http://lists.linaro.org/mailman/listinfo/linaro-dev > _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
