Re: Setting MTRRs for K6

Alan Cox (alan@lxorguk.ukuu.org.uk)
Sun, 4 Jul 1999 22:21:52 +0100 (BST)


> 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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