Fix for Ubuntu 8.04 64bit 4gig ram and fglrx driver using mttr

I’ve seen I’m not the only one running a 64 bit Ubuntu Hardy and running into a problem starting Xorg with the fgrlx driver when using 3+ gig of ram.

My Xorg is running (without crashes so far) for a few days now, thanks to this fix at the ubuntu forum.

I’m using a script during startup that applies the patch and then starts kdm.

Here’s the fix (as seen in the ubuntu forum, link above):

#!/bin/sh
# Fixup /proc/mtrr
echo "disable=2" >| /proc/mtrr
echo "disable=1" >| /proc/mtrr
echo "disable=3" >| /proc/mtrr
echo "disable=4" >| /proc/mtrr
echo "disable=0" >| /proc/mtrr
echo "base=0x00000000 size=0x80000000 type=write-back" >| /proc/mtrr
echo "base=0x80000000 size=0x40000000 type=write-back" >| /proc/mtrr
echo "base=0xC0000000 size=0x10000000 type=write-back" >| /proc/mtrr
echo "base=0x100000000 size=0x20000000 type=write-back" >| /proc/mtrr
echo "base=0x120000000 size=0x10000000 type=write-back" >| /proc/mtrr

I’m using a ATI 3870, and a P35 chipset.