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
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?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
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