Comment 123 for bug 314928

ticket (tickettothemoon2004) wrote :

Although I understand this issue is fixed in karmic, I found that if I issue (under karmic)

  cat /proc/mtrr

I see the output shows that mtrr is not set up.
I can fix it for my gpu card by issuing a

sudo -s
echo "base=0xe0000000 size=0x10000000 type=write-combining" >| /proc/mtrr

If I put the echo command inside /etc/gdm/PostLogin/Default , it is ignored in karmic (wasn't in jaunty). I can make it stick by putting it in /etc/rc.local (but with the provisos noted by the posts above).

With mtrr correctly setup, their is a very slight improvement in flash performance, so it appears to be doing something. I am not using an intel gpu - I have an nVidia one.

My /boot/config-2.6.31-15-generic contains

CONFIG_MTRR=y
CONFIG_MTRR_SANITIZER=y
CONFIG_MTRR_SANITIZER_ENABLE_DEFAULT=0
CONFIG_MTRR_SANITIZER_SPARE_REG_NR_DEFAULT=1
CONFIG_X86_PAT=y

So does this mean I don't need to set up mtrr in karmic? And it is safe to ignore the wrong setup reported by cat /proc/mtrr ?