Re: [PATCH] X86: MM: Add PAT Type write-through in combination withmtrr

From: Borislav Petkov
Date: Mon Oct 28 2013 - 06:57:38 EST

On Mon, Oct 28, 2013 at 11:34:28AM +0100, Andreas Werner wrote:
> Yes the reads are only for packet data, the commands or configuration
> registers are mapped non cachable.
> IÂve tried WB, but on PCIe Tracer i could not see any burst access.
> Thats the reason why i have created this patch.
> Is there a chance to get this patch into the kernel? Or
> is this solution so special?

Ok, but your patch returns WB pat type for WT MTRR type, AFAICT.

You want to do:

PAT=Write-Back + MTRR=Write-Through = Effective Memory of Write-Through

but you end up doing

PAT=Write-Back + MTRR=Write-Through = Effective Memory of Write-Back

What am I missing or misunderstanding?

AFAICT, you want to return _PAGE_PWT for MTRR_TYPE_WRTHROUGH, no?


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