Re: Intel's response Linux/MTRR/8GB Memory Support / Why doesn't the kernel realize the BIOS has problems and re-map appropriately?

From: Jesse Barnes
Date: Fri Jun 01 2007 - 17:42:24 EST


On Friday, June 1, 2007 2:19:43 Andi Kleen wrote:
> And normally the MTRRs win, don't they (if I remember the table correctly)
> So if the MTRR says UC and PAT disagrees it might not actually help

I just checked, yes the MTRRs win for UC types. But it sounds like the cases
we're talking about are actually situations where there's no MTRR coverage,
so the default type is used. The manual doesn't specifically call out how
memory using the default type interacts with PAT, but it may well be that it
stays uncached if the default type is uncached. Again that argues for fixing
the MTRR mapping problem in some way.

Thanks,
Jesse
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