mtrr failure, 3.1-rc1

From: Anders Eriksson
Date: Thu Aug 25 2011 - 03:30:15 EST




My old P-II has 640MB ram, but the bios only sets up WC for the first 512, so i
add this early in the boot process:
echo "base=0x20000000 size=0x8000000 type=write-back" > /proc/mtrr

For reasons I have forgot I also have to add 'disable_mtrr_check' to the
command line. Works great.

As of merge dc43d9fa73d82083656fb9c02f4823bcdcfb9f91 This no longer works.
Adding that line to /proc/mtrr no longer has any effect (cat /proc/mtrr shows
only the reg00 entry).

Reverting that merge on top of rc3 brings things back to normal and /proc/mtrr
shows:
reg00: base=0x000000000 ( 0MB), size= 512MB, count=1: write-back
reg01: base=0x048000000 ( 1152MB), size= 128MB, count=1: write-combining
reg02: base=0x020000000 ( 512MB), size= 128MB, count=2: write-back

Any ideas how to track this down futher? Would be good to get it fixed for 3.1

-Anders


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