Re: SIMD vs no SIMD on i686 (was: [Bug 3975] executable stack flag prevents use of libx264.so.148 with selinux in enforcing mode)

On Ter, 2016-07-19 at 09:35 +0200, Nicolas Chauvet wrote: > 2016-07-19 2:55 GMT+02:00 <dominik(a)greysector.net&gt;: > > > > Hello, Sérgio. > > > > On Tuesday, 19 July 2016 at 02:35, RPM Fusion Bugzilla wrote: > > > > > > https://bugzilla.rpmfusion.org/show_bug.cgi?id=3975 > > > > > > --- Comment #4 from Sérgio Basto <sergio(a)serjux.com&gt; 2016-07-19 > > > 02:35:19 CEST --- > > > (In reply to comment #3) > > > > > > > > I'll take a look at this. Could you try running execstack -c on > > > > the installed > > > > library in the meantime? > > > Be my guest , in meantime I read your thread on packaging > > > Mailing list about > > > sse3 , I'd like understand if we need 2 builds for i686 ... one > > > with sse2 other > > > without it, can you give us your opinion ? > > The only real concern here are applications linked against libx264, > > which someone might want to run on low-end hardware, because I > > don't > > think anyone would want to encode anything to H.264 on non-SSE2 > > capable > > CPU (i.e. Pentium 3 or Athlon XP and older). Considering last non- > > SSE2 > > CPUs went out of production about 8 years ago, I think it's fairly > > safe > > to assume that the impact of doing SSE2-only builds would be > > negligible, > > if any. > I'm okay to have a SSE2 only build for single binaries such as pcsx2 > for the following reasons: > - pcsx2 requires more CPU resources than barely capable sse2 CPU > anyway. > - Using sse2 will allow older but sse2 capable CPU to run. > - Runtime test has to be made to avoid crash and notify user if the > CPU don't have sse2. > > But for libraries it's not possible to assume a given usage and > ensure > users notification. > I expect you can have webcam app to encode to h264 low profile just > fine using x264 even on non-sse2 capable cpu. > It's expected not to crash here. As I state before, I think, even in this case, x264 asm code, have a fall back when don't have sse2 instructions and don't crash, that is my point, but just testing to be sure. I don't see any hardware here to test it, even though it is a big challenge try install Fedora 24 in a non-sse2 capable cpu .