这个会导致nvidia的驱动不能加速2d，解决方案一般就是重写mtrr表。

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=0×00000000 size=0×80000000 type=write-back” >| /proc/mtrr
echo “base=0×80000000 size=0×40000000 type=write-back” >| /proc/mtrr
echo “base=0xC0000000 size=0×10000000 type=write-back” >| /proc/mtrr
echo “base=0×100000000 size=0×20000000 type=write-back” >| /proc/mtrr
echo “base=0×120000000 size=0×10000000 type=write-back” >| /proc/mtrr