Ubuntu
xserver-xorg-video-intel package

  1. Bug #370552
  2. Comment #2

Comment 2 for bug 370552

Revision history for this message
Robert Hooker (sarvatt) wrote :

Aspire ones have buggy MTRR's by default, you have to boot with enable_mtrr_cleanup mtrr_spare_reg_nr=1 added to your grub default options to fix it.

[ 0.000000] MTRR default type: uncachable
[ 0.000000] MTRR fixed ranges enabled:
[ 0.000000] 00000-9FFFF write-back
[ 0.000000] A0000-BFFFF uncachable
[ 0.000000] C0000-C7FFF write-protect
[ 0.000000] C8000-EFFFF uncachable
[ 0.000000] F0000-FFFFF write-protect
[ 0.000000] MTRR variable ranges enabled:
[ 0.000000] 0 base 0FFFE0000 mask 0FFFE0000 write-protect
[ 0.000000] 1 base 0FFFC0000 mask 0FFFE0000 uncachable
[ 0.000000] 2 base 000000000 mask 0C0000000 write-back
[ 0.000000] 3 base 040000000 mask 0E0000000 write-back
[ 0.000000] 4 base 05F800000 mask 0FF800000 uncachable
[ 0.000000] 5 base 05F600000 mask 0FFE00000 uncachable
[ 0.000000] 6 base 05F500000 mask 0FFF00000 uncachable
[ 0.000000] 7 base 000000000 mask 0FFFE0000 uncachable
[ 0.000000] original variable MTRRs
[ 0.000000] reg 0, base: 4194176KB, range: 128KB, type WP
[ 0.000000] reg 1, base: 4194048KB, range: 128KB, type UC
[ 0.000000] reg 2, base: 0GB, range: 1GB, type WB
[ 0.000000] reg 3, base: 1GB, range: 512MB, type WB
[ 0.000000] reg 4, base: 1528MB, range: 8MB, type UC
[ 0.000000] reg 5, base: 1526MB, range: 2MB, type UC
[ 0.000000] reg 6, base: 1525MB, range: 1MB, type UC
[ 0.000000] reg 7, base: 0GB, range: 128KB, type UC
[ 0.000000] WARNING: BIOS bug: VAR MTRR 7 contains strange UC entry under 1M, check with your system vendor!

with mtrr cleanup and 1 spare reg you get

reg00: base=0x000000000 ( 0MB), size= 1024MB, count=1: write-back
reg01: base=0x040000000 ( 1024MB), size= 512MB, count=1: write-back
reg02: base=0x05f500000 ( 1525MB), size= 1MB, count=1: uncachable
reg03: base=0x05f600000 ( 1526MB), size= 2MB, count=1: uncachable
reg04: base=0x05f800000 ( 1528MB), size= 8MB, count=1: uncachable
reg05: base=0x060000000 ( 1536MB), size= 256MB, count=1: write-combining

so you actually get write combining for your video ram. Just edit your /boot/grub/menu.lst and add enable_mtrr_cleanup mtrr_spare_reg_nr=1 to your defoptions line and sudo update-grub afterwards.