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

[Andi Kleen]

On Mon, Jun 04, 2007 at 05:59:59PM -0700, Yinghai Lu wrote:
> On 6/4/07, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
> >
> >Exactly, and given that this is a fairly easy thing to do, and that
> >occasionally we see systems where this happens (even if their BIOS is
> >later fixed).  It is likely worth it for someone to write up the patch
> >and that compare MTRRs with available memory, and to complain and
> >reserve all memory that MTRRs claim is not write-back.
> >
> that is good.
> Sometime BIOS can not even keep mtrr to the identical between
> different CPU in SMP system.

The MTRR code already fixes this case. Or at least mostly -- 
it doesn't do it for fixed size MTRRs.

> Or reset mtrr according to e820 table.

That would be likely dangerous.

-Andi
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