Re: re: PAT support

[David Young <dyoung%pobox.com@localhost>]

On Wed, May 19, 2010 at 11:43:00AM +0200, Christoph Egger wrote:
> The following memory types exist:
> 
>    - Uncacheable
>    - Write-Combining
>    - Write-Protect
>    - Write-Through
>    - Writeback
>    - Uncacheable Minus

IIUC, the memory type set by PAT applies at VA -> PA mapping.  Can't one
physical page be mapped at two VAs with conflicting memory types?

On one physical range, can PAT and MTRR simultaneously set conflicting
memory types?  Can we detect/avoid the conflict?

Are some memory types more suitable for a DMA buffer than others?

Where PAT is not available, can't we fall back to using a facility such
as MTRR to set memory types?

Dave

-- 
David Young             OJC Technologies
dyoung%ojctech.com@localhost      Urbana, IL * (217) 278-3933