$ cat /proc/mtrr reg00: base=0xc0000000 (3072MB), size=1024MB: uncachable, count=1 reg01: base=0x00000000 ( 0MB), size=4096MB: write-back, count=1
Yes, that's set up wrong. The IOMMU and AGP spaces can't be uncachable, since uncachable overrides all other cache settings.
You should look for a memory settings option which specifies "discrete" or "continuous", and change the value. Hopefully, that will return some of your memory to you.
You should also look to see if there are any memory hoisting options available.
Nothing like that in the BIOS menu.
It's been three years since AMD required those options; I don't believe your motherboard have been EOL'd at that point.
The best I seem to be able to do is adjust interleaving.
That won't help, as I'm sure you've noticed.
If you're feeling adventurous, you check to see if there are any patches available to enable PAT. I know Andi was/is working on them, but I'm not sure how far along he is.
Got a URL? All I'm finding from google are the odd linux-kernel post. There's an initial patch, but it looks highly theoretical (I don't see any /proc support I might reasonably use).
Again, I know Andi is working on it, but I'm not sure of the status. You may want to check with him, or ping me again in October. -Mark Langsdorf AMD, Inc.