I have an MSI K8D-Master-F motherboard with two Opteron 244's. It recently got retasked as a desktop machine due to another system's failure...I thought the little ATI Rage built into the motherboard would make more than a sufficient 2d desktop type framebuffer, and as far as other stuff inside this box... this should be a pretty kick ass, high performance workstation.
But I can literally watch the screen redraw if I switch virtual desktops. Painfully slow. Thinking this was just some crippled built-in video bug, I threw in an old nVidia card we had lying around in one of the regular PCI slots. Slightly slower, if you can believe it.
I think this:
mtrr: type mismatch for e5000000,1000000 old: uncachable new: write-combining
And of course this:
$ 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.
3) How do I get the system to put the IOMMU somewhere in the range it stole under 4G (so Linux can use it)? Can Linux move this on its own accord?
Linux can move this on it's own accord, but until you fix the MTRRs (which Linux can't currently do), it isn't going to help. 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. -Mark Langsdorf AMD, Inc.