F22 System Wide Change: Harden all packages with position-independent code

[drago01]

On Mon, Jan 19, 2015 at 3:42 PM, Reindl Harald <h.reindl at thelounge.net> 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:

1) mmx is basically obsolete
2) sse2 is the default fp ABI on x86_64 anyway and thus supported by
*all* x86_64 cpus
3) Requiring sse4.2 or even 4.1 would exclude a lot of hardware
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) .. most applications where it really matters do
detection at runtime (even glibc does that)