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

[R Hill]

Michael Marineau wrote:
  > Chris White wrote:
>>Michael Marineau wrote:
>>
>>>What's the point of a use flag if you purposfully use the sse useflag to
>>>do something different?  this sort of thing would make more sense:
>>>
>>>sse = sse's integer logic
>>>sse = sse's floating point stuff
>>>mmx2 = mmx2
>>
>>
>>Problem mmx2 = sse (on intel)
>>mmx2 = I don't know what (on amd)
>>mmx2 != mmxext
>
> Weird, so where does this mmx2 name come from then if it's just sse?

Hey.  I'm the complaining users. ;]

This has been bugging me so I've been doing some digging, trying to put 
together some kind of idea of how everything fits.  I hope it helps make 
some sense.  Basically, you can see what i came up with in this post.

http://forums.gentoo.org/viewtopic-t-310794.html

I'm a little hazy about the AMD side of it, as I've no experience with 
them.  What I do know for sure is that back in '99, Intel was hyping the 
new KNI (Katmai New Instructions) instruction set, aka Pentium III.  You 
can see references to it in articles around that time (see forum post). 
  Up until the the actual release of the Katmai these articles often use 
KNI and MMX2 interchangably.  The best source I can find that I trust 
not to be PR fluff is http://www.tbcnet.com/~clive/katmai.html - where 
it's stated "The official name for Katmai is Pentium III, what the new 
opcodes are called is still in the air, is it MMX2, KNI or perhaps 
XMM?".  The name that Intel did finally settle on was Streaming SIMD 
Extensions - SSE.  So, for all intents and purposes MMX2 = SSE.

Now AMD had the 3DNow! instruction set which they introduced with the 
K6-2 in '98, as a SIMD extension to MMX.  SSE/MMX2 was brought in after 
that by Intel.  So MMX2 != AMD and never did.  AMD did later integrate 
SSE into the 3DNow Pro though.  So what the hell is MMXExt?  I think 
it's an old name for the original integer instructions extensions the 
3DNow made to MMX.  That's a very sketchy conclusion though and I 
wouldn't be surprised to be proven wrong.  I can say for certain that it 
is AMD specific.  If you want proof: 
http://forums.gentoo.org/viewtopic-t-103757.html ;]

As to how to apply all this to MPlayer..

o.O


obl refs-
http://en.wikipedia.org/wiki/Streaming_SIMD_Extensions
http://en.wikipedia.org/wiki/3DNow%21
http://www.tommesani.com/3DNow.html
http://www.intel.com/pressroom/archive/releases/dp022699.htm
http://developer.intel.com/design/pentiumii/manuals/245127.htm


r.

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