[coreboot] Crazy Intel graphics mtrr

[joe at settoplinux.org]

Hello,
I am noticing some X problems (slow, crashes once and a while) on the RCA RM4100. I think this is related to the crazy way coreboot setup the mtrr. For some reason when the Intel onboard graphics are enabled, coreboot sets up this crazy looking mtrr. I don't think they should all be write-back? Isn't write-combining faster for graphics? Does it need to have a uncachable area?

coreboot onboard graphics disabled
[root at localhost ~]# cat /proc/mtrr
reg00: base=0x00000000 (   0MB), size= 128MB: write-back, count=1

coreboot onboard graphics enabled
[root at localhost ~]# cat /proc/mtrr
reg00: base=0x00000000 (   0MB), size=  64MB: write-back, count=1
reg01: base=0x04000000 (  64MB), size=  32MB: write-back, count=1
reg02: base=0x06000000 (  96MB), size=  16MB: write-back, count=1
reg03: base=0x07000000 ( 112MB), size=   8MB: write-back, count=1

factory bios onboard graphics enabled
[root at localhost ~]# cat /proc/mtrr
reg00: base=0x07800000 ( 120MB), size=   8MB: uncachable, count=1
reg01: base=0x00000000 (   0MB), size= 128MB: write-back, count=1
reg02: base=0xf0000000 (3840MB), size= 128MB: write-combining, count=3


-- 
Thanks,
Joseph Smith
Set-Top-Linux
www.settoplinux.org