Ok, so I tried to play around with that a little bit. With memory remapping, /proc/mtrr looks like that: reg00: base=0x00000000 ( 0MB), size=4096MB: write-back, count=1 reg01: base=0x100000000 (4096MB), size= 512MB: write-back, count=1 reg02: base=0xe0000000 (3584MB), size= 512MB: uncachable, count=1 reg03: base=0xe0000000 (3584MB), size= 128MB: write-combining, count=1
This doesn't work. If your BIOS is doing this (as opposed to you mucking with the settings), I need to get the AMD BIOS developers to talk to your BIOS developers.
sorry for warming up such an old thread :-) I just tested the latest beta bios for the Asus A8V Deluxe (1015.002 from Oct 19th) to check if they had added sth. about discrete/continuous MTRRs. Unfortunately they still haven't. What's changed is the amount of memory available without remapping the memory hole: At least 3.8 of the 4GB are available, in contrats to 3.5 and 3.3 with earlier bios versions.
However, with "hardware memory hole" enabled in the bios, all the 4 GB are available for linux, but things like fglrx still can't load and the /proc/mtrr looks like this:
cantor:~ # cat /proc/mtrr reg00: base=0x00000000 ( 0MB), size=4096MB: write-back, count=1 reg01: base=0x100000000 (4096MB), size= 256MB: write-back, count=1 reg02: base=0xf0000000 (3840MB), size= 256MB: uncachable, count=1 reg03: base=0xf0000000 (3840MB), size= 128MB: write-combining, count=1
Do you see a chance to get the AMD bios guys make the ASUS people do *some* real work at last? ;-))
They do real work all the time. They just sometimes don't do it right. I will go have another discussion about why making the video aperture uncachable is not the same thing as leaving it unassigned. -Mark Langsdorf AMD, Inc.