Am 02.05.2015 um 14:06 schrieb Nikos Chantziaras: > On 02/05/15 14:37, Volker Armin Hemmann wrote: >> Am 02.05.2015 um 13:25 schrieb Nikos Chantziaras: >>>>> >>>>> The kernel uses -O2 and several -march variants (e.g. -march=core2). >>>>> Several other options are used to prevent GCC from generating >>>>> unsuitable code. >>>>> >>>>> Specifying another -march variant does not affect the optimizer >>>>> though. It only affects the code generator. If you don't modify the >>>>> other CFLAGS and only change -march, you will not get FP instructions >>>>> unless you use FP in the code. >>>> >>>> http://www.agner.org/optimize/calling_conventions.pdf >>> >>> Not sure what you're trying to say. >>> >> >> that simd is not save in kernel if not carefully guarded. >> >> Really people, just don't fuck around with the cflags. > > I still fail to see the relevance. Unless you mean using a different > -O level. In that case, yes. You shouldn't. But I was talking about > -march. >
you said this > > (note that SIMD is not FP and is perfectly fine in the kernel.) and I have shown you that you are wrong.
