The local USE flag "mmxext" is documented as both "mmx2" and "MMXExt", neither of which is correct. As far as I can tell, there is no SIMD instruction set called "MMX2", only a new/forthcoming wireless streaming technology from Intel with that name, and OK, "MMXExt" is almost correct. I'm pretty sure this flag should be documented as "Extended MMX", which is a short-lived SIMD instruction set from Cyrix. See here for details: http://en.wikipedia.org/wiki/Extended_MMX I'm no expert on this matter, so I might be wrong, but either way, the descriptions are inconsistent and unclear. Cheers. Reproducible: Always Steps to Reproduce: 1. euse -i mmxext Actual Results: global use flags (searching: mmxext) ************************************************************ no matching entries found local use flags (searching: mmxext) ************************************************************ [- ] mmxext (media-plugins/vdr-softdevice): enables MMXExt support [- ] mmxext (media-video/ffmpeg): Enables mmx2 support [- ] mmxext (media-video/mplayer): Enables mmx2 support Expected Results: global use flags (searching: mmxext) ************************************************************ no matching entries found local use flags (searching: mmxext) ************************************************************ [- ] mmxext (media-plugins/vdr-softdevice): enables Extended MMX support [- ] mmxext (media-video/ffmpeg): Enables Extended MMX support [- ] mmxext (media-video/mplayer): Enables Extended MMX support
For reference, I just go with whatever upstream calls it. mplayer: --enable-mmxext enable MMX2 (Pentium III, Athlon) [autodetect] ffmpeg: --disable-mmx2 disable MMX2 usage Besides, mmxext fits because that's the the CPU procflag is. flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow rep_good pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy 3dnowprefetch Either way, I'm indifferent to updating the description, but I really doubt anyone would be confused.
Fair enough, I agree that it's pretty trivial. I just wanted to point it out. :)
(In reply to comment #1) > Either way, I'm indifferent to updating the description, but I really doubt > anyone would be confused. Well, I was confused. ffmpeg update here added 3dnowext and mmxext useflags. So, I went to check out what do they mean... $ euse -i 3dnowext mmxext There was only one description that was really helpful: [- ] 3dnowext (media-video/ffmpeg): Enable manually-optimised routines using the AMD 3DNow!Ex SIMD instruction set, present in modern AMD CPUs. (Check for 3dnowext in /proc/cpuinfo to know whehter you support it). I wish mmxext description was as helpful as that. (by the way, there is a typo at that description)
