Sorry for spreading misinformation about the K6 ;-)
I'll collect this with the Cyrix info I have and send a patch to Richard
Gooch for a new multi-vendor Documentation/mtrr.txt.
I think your comments below just about cover the AMD specifics. Anything
else that AMD users need to know about setting their mtrr?
Cheers,
-Rafael
On Sun, 4 Jul 1999, Alan Cox wrote:
> > On a AMD K6 you are given only two mtrr's, so one will go to main memory
> > and the other to video ram. I'm not sure how the non-power of two memory
>
> The main memory on a K6 is handled seperately to the MTRR's. So you have
> one for the video, and one to mask out the mmio space (or one for video
> and one for texture maps)
>
> > Finally, this is usually handled properly by the BIOS and if not by the
> > kernel for the main memory case (not so for video ram.) The fact that
> > on boot both registers are empty makes me suspicious that something is not
> > right in the kernel driver.
>
> The memory case is handled by the BIOS. Its seperate to the MTRR. If it is
> misconfigured by the bios (eg modern K6-2 in an older board) the kernel
> actually goes and sets it during boot too.
>
> Alan
>
-
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