Re: [gentoo-dev] MPlayer cpu USE flags zaniness

[Drake Wyrm]

At 2005-03-27T06:46:16+0200, Markus Nigbur <pYrania@g.o> wrote:
> On Sun, 2005-03-27 at 12:48 +0900, Chris White wrote:
> >     Ok, so I had some users complain about mmx2 being showed as enabled
> > in mplayer despite the lack of mmxext in /proc/cpuinfo.  Therefore I
> > decided to get upstream help.  Here's what we got...:
> >
> > mmx2 = sse
> > sse = mmx2
> >
> > but in mplayer's configure script:
> >
> > mmx2 = sse's integer logic
> > sse = sse's floating point stuff
> >
> > so mmx2 is NOT a flag for mmx2 support.. it's a flag for integer portion
> > of sse...
> >
> > ok, so at this point I'm confused as to how to approach this.  What
> > about AMD?  Do they use mmxext for stuff like that.. or sse2 extensions
> > (as someone mentioned).  My plan is to have sse USE flag enable mmx2
> > only (since it's "the best") and disable sse (since it's the same thing
> > but "worse").  However, that only takes care of intel.. what about AMD
> > processors though?  They deal with all this stuff differently.
> That sounds very brain dead by upstream. IMHO they really shouldn't use
> keywords for things which don't do what everybody else would expect them
> to do. Did you already propose them to change this behavior and
> introduce either another keyword for the floating point stuff or merge
> those two, enabling it by default when sse is enabled.

There was a li'l thread about this recently. The terms "mmxext" and
"mmx2" both refer to the "AMD Extensions to the MMX Instruction Set",
introduced by AMD right at the end of the K6-3 line and beginning of the
Athlon line. Intel included these instructions in their "Streaming SIMD
Extensions" (SSE).

Take a look in mplayer's ./configure script to see how the mplayer devs
autodetect for "--enable-mmx2".

     650     mmxext)       _mmx2=yes                ;;
     652     xmm|sse|kni)  _sse=yes    _mmx2=yes    ;;

Looks like you've got it right in the ebuilds currently in portage.

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