# MMXEXT / MMX2

## rhill

recently i noticed the mmx2 USE flag on the mplayer ebuild got changed to mmxext.  this started me thinking and i realized i had no idea what either one of them actually were.  so i did some searching.

i have a Katmai P3-450.  according to /proc/cpuinfo this processor supports only MMX and SSE.  

```
processor   : 0

vendor_id   : GenuineIntel

cpu family   : 6

model      : 7

model name   : Pentium III (Katmai)

stepping   : 3

cpu MHz      : 504.756

cache size   : 512 KB

fpu      : yes

fpu_exception   : yes

cpuid level   : 2

wp      : yes

flags      : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 mmx fxsr sse

bogomips   : 997.37
```

Mplayer on the other hand always complains when i don't compile in MMX2 support.  So i do, thinking maybe MPlayer is smokin the rock a bit too much but hey it makes it happy and it plays my movies so i don't care.

Now, looking into MMX2, i can find a lot of buzz during 98-99 about the Katmai's new instruction set (aka KNI).  I'm assuming this either got merged under the MMX umbrella or got renamed (SSE?), because Intel appears to be reusing the name now for their 64bit wireless stuff.

So what is MMXEXT then?  From what little I can find, it's an AMD thing, so i don't think i fall under that category.

so i guess my questions would be:  What is MPlayer referring to when it says MMX2?  If MMX2 got renamed to SSE, then why does MPlayer support both?  If MMX2 refers to the 64bit wireless version, why is it saying I can support it?  and finally, what is MMXEXT, and where does it fit into all this?

thanks for your time.

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## SubTexel

MMX2 was released back in the 98-99 timeframe to fix some short falls of the original MMX. So yes, your Processor has MMX2, I know my Coppermines on my SMP box do (note, it does not list it in the cpuinfo.. But, its there..) MMXExtended is for Athlon XP and above.. Just google Pentium 3 + MMX2 and you'll find a lot of old reviews that talk about it.

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