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SubjectRe: activating mttr on voodoo 3

>I putted the first address in /proc/mtrr (under 2.3.48), restarted X, and
>after 3 seconds up, I had a system freeze and had to do a hard ( button)
>reboot.

>Am I doing the procedure wrong, or is mtrr broken (It didn't compile
>in 2.3.47).

It's fixed now, and even in 2.3.47 it was just due to a typo. The MTRR
stuff works great, but in fact you are doing it wrong :)

The X server memory range thing shows both the non-prefetchable range and
the prefetchable range ; the second one is actually the range you want to
use. To be sure, cat /proc/pci which will explicitly tell you which is
which.

I have a V3 3000; assuming your memory ranges are like mine, you'd enter
the following:

echo "base=0xfc000000 size=0x1000000 type=write-combining" > /proc/mtrr

This will yield (in /proc/mtrr):

reg00: base=0x00000000 ( 0MB), size= 128MB: write-back, count=1
reg01: base=0xfc000000 (4032MB), size= 16MB: write-combining, count=1

There is a noticeable speedup in 2-D when you use this ; I don't think 3-D
is affected though.

Phil D.


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