Re: 36 bit MTRRs, Re: test10-pre1 problems on 4-way SuperServer8050

From: Tigran Aivazian (
Date: Thu Oct 12 2000 - 06:23:53 EST

On Thu, 12 Oct 2000, Boszormenyi Zoltan wrote:

> On Thu, 12 Oct 2000, Boszormenyi Zoltan wrote:
> > echo "base=0 size=0x100000000 type=write-back" >/proc/mtrr
> > echo "base=0x100000000 size=0x80000000 type=write-back" >/proc/mtrr
> > echo "base=0xfe000000 size=0x800000 type=write-combining" >/proc/mtrr
> > echo "base=0xfde00000 size=0x100000 type=uncached" >/proc/mtrr
> > echo "base=0xfe800000 size=0x100000 type=uncached" >/proc/mtrr
> > echo "base=0xfe9ed000 size=0x1000 type=uncached" >/proc/mtrr
> > echo "base=0xfe9ee000 size=0x2000 type=uncached" >/proc/mtrr
> > echo "base=0xfeafe000 size=0x2000 type=uncached" >/proc/mtrr
> Sorry, use 'uncachable' instead of 'uncached'. :-(

ok, doing it from the bottom up was fine (didn't lockup) but reaching the
last (first in your list) entry was refused by mtrr:

mtrr: 0x0,0x100000000 overlaps existing 0xfeafe000,0x2000

# cat /proc/mtrr
reg00: base=0xfeafe000 (4074MB), size= 0kB: uncachable, count=1
reg01: base=0xfe9ee000 (4073MB), size= 0kB: uncachable, count=1
reg02: base=0xfe9ed000 (4073MB), size= 0kB: uncachable, count=1
reg03: base=0xfe800000 (4072MB), size= 1MB: uncachable, count=1
reg04: base=0xfde00000 (4062MB), size= 1MB: uncachable, count=1
reg05: base=0xfe000000 (4064MB), size= 8MB: write-combining, count=1
reg06: base=0x00100000000 ( 4096MB), size= 2048MB: write-back,

and machine is still slow. So, what is the correct way to cover the 6G by
some mtrrs? I will now try to disable or change strategy of L2 caching in
BIOS and see if it makes things worse.


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