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. You can not overlap *anything* with uncacheable and get anything but uncacheable back. Uncacheable trumps all other MTRR settings. See p 229 of http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/ 24593.pdf You may want to check if your BIOS has an option for "Discrete" or "continuous" usage of MTRRs. Experiment with both settings - I believe "discrete" should work better in a memory hoisting environmnet. -Mark Langsdorf AMD, Inc.