On Mon, Jan 19, 2015 at 9:41 PM, Reindl Harald <h.reindl@xxxxxxxxxxxxx> wrote: > > > Am 19.01.2015 um 21:34 schrieb drago01: >> >> On Mon, Jan 19, 2015 at 3:42 PM, Reindl Harald <h.reindl@xxxxxxxxxxxxx> >> wrote: >>> >>> >>> Am 19.01.2015 um 15:28 schrieb Gerd Hoffmann: >>>>>> >>>>>> >>>>>> Would that make it impossible to run fedora on sse-only i686 CPUs? >>>>> >>>>> >>>>> >>>>> Yes, but test coverage for those CPUs is already rather poor, so I >>>>> don't >>>>> expect them to work anymore. >>>> >>>> >>>> >>>> See other replies, people are running such machines. >>>> >>>> Given x86_64 exists for many years and even embedded (see aarch64) is >>>> moving to 64bit these days i386 clearly is for old legacy hardware. If >>>> you need performance you don't run a i386 machine. >>>> >>>> So, why bother raising the bar for i386 by requiring more cpu features? >>>> It doesn't help anyone. >>> >>> >>> >>> "rpmrc" has optflags: for different architectures >>> >>> so why not optimize only "optflags: x86_64" for more recent hardware? >>> since i686 is a complete different build anyways it won't matter >>> >>> on my private builders it's "-mmmx -msse2 -msse3 -msse4.1 -msse4.2 -maes >>> -mfpmath=sse" >> >> >> Because that doesn't make sense for multiple reasons: > > > you show none below because it said "keep i686 flags unchanged" > >> 1) mmx is basically obsolete > > > in theory And in practice. Why would you want to use mmx if you have sse2+ available? (you don't). >> 2) sse2 is the default fp ABI on x86_64 anyway and thus supported by >> *all* x86_64 cpus > > > so be it > >> 3) Requiring sse4.2 or even 4.1 would exclude a lot of hardware > > > did i propose that? It wasn't clear from your mail what your proposal actually is. > i said "private builders" to show that keep supporting > 10 years old > hardware is just silly because you waste HW capabilities - noweher did i > propose *that* falgs > >> 4) You don't just throw in some compiler flags and assume it will gain >> you anything (you'd probably have to either turn on O3 or >> vectorization as well) > > > -O3 is the default for my builds starting with 2006 > >> .. most applications where it really matters do >> detection at runtime (even glibc does that) > > > the topic is still: hwta can be changed in the x86_64 flags *without* break > old 32bit crap some people rely for several reasons OK .. well there is no reason why the flags have to be shared between x86_64 and the "32bit crap" ... if you stop carring about 32bit *hardware* we could use sse2 just fine for i686 (people using 32bit applications on top of x86_64 would benefit from it). -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
