Re: [PATCH] x86: mtrr cleanup for converting continuous to discrete layout v2

From: Arjan van de Ven
Date: Tue Apr 29 2008 - 09:00:50 EST


On Mon, 28 Apr 2008 17:28:21 +0200
Mika Fischer <mika.fischer@xxxxxxxxxx> wrote:

> Arjan van de Ven schrieb:
> > yep one should not touch existing MTRRs. If you run out, tough luck.
> > Thats what we have PAT for.
> > Changing them anyway is a deathtrap with various things,
> > suspend/resume being only one of the nasty cases.
>
> Hm. I currently have to remove the offending (i.e. overlapping my
> video memory) MTRRs and split them so that they have a hole where my
> video memory is.

I'm not arguing that it sometimes works. It's just a big trap to default enable ;(


>
> Ah, so the new X will be able to use the video memory in
> write-combining mode even if I have an MTRR saying this area is
> uncachable or write-back?

yes.
When it gets released...
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