On Mon, Feb 3, 2014 at 12:36 PM, Reinhard Tartler <siret...@gmail.com> wrote: > On Mon, Feb 3, 2014 at 9:02 AM, Fabian Greffrath <fab...@greffrath.com> wrote: >> Am Montag, den 03.02.2014, 10:41 -0300 schrieb Felipe Sateler: >>> I have some packages that also add (on amd64 and i386) -mtune=generic. >>> This causes the compiler to optimize for the most common cpus, but >>> still be compatible with older ones. >> >> Isn't GCC smart enough to know that it can use SSE optimizations on >> amd64? > > I strongly believe it is, if GCC was not, then it should be fixed.
Indeed, that should be the correct solution. > > Please be careful with adding those flags. They instruct gcc to emit > code that does not work on some machines. The admitedlyonly way to use > them correctly is to ensure that the emitted code is only used on > machines that actually supports that. The mtune flag instructs the compiler to optimize for a certain instruction set, but still provide a fallback for when the instrucions are not available. I don't know if this includes the use of SSE or other coprocessor. http://stackoverflow.com/questions/10559275/gcc-how-is-march-different-from-mtune > > We've been burned with that previously. In Libav, we're installing the > libraries into special "magic" paths that the dynamic linker only > includes if the hardware is capable. This works only on libraries, but > not for programs (and there are still open bugs for that, for instance > with mplayer/mplayer2 and possibly mpv, all for powerpc, admittedly). > > If you are unsure on those flags, better not enable them. I think sse is required by the amd64 spec, so no point in not using it (wikipedia agrees). -- Saludos, Felipe Sateler _______________________________________________ pkg-multimedia-maintainers mailing list pkg-multimedia-maintainers@lists.alioth.debian.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/pkg-multimedia-maintainers
