Re: question about MTRR areas on x86_64

[Markus Lidel]

Hello,

Eric W. Biederman wrote:
> Andi Kleen <ak@xxxxxx> writes:
> > Markus Lidel <Markus.Lidel@xxxxxxxxxxxxxxxxx> writes:
> > > Could it be because the machine has too much memory, or is there a bug in the
> > I2O driver?
> >
> > The problem comes from the BIOS who set up reg00 to be overlapping
> > over other areas. The Linux MTRR driver cannot deal with overlapping
> > MTRRs, in fact it is sometimes impossible because it could run
> > out of registers or violate some of the MTRR restrictions.

Sorry, for not answering, but somehow i never received your e-mail. :-(

> And the BIOS is using overlapping MTRRs because otherwise it would run
> out.

Okay...

> > It's a long standing problem, eventual fix will be to get rid
> > of MTRRs completely and only use PAT. But it needs a bit more work.

I've seen there is already a patch around to add initial PAT support. So 
i think it's only a question of time until it is included :-D If there is 
something i could help with please let me know.

Thanks to both of you for helping.



Best regards,


Markus Lidel
------------------------------------------
Markus Lidel (Senior IT Consultant)

Shadow Connect GmbH
Carl-Reisch-Weg 12
D-86381 Krumbach
Germany

Phone:  +49 82 82/99 51-0
Fax:    +49 82 82/99 51-11

E-Mail: Markus.Lidel@xxxxxxxxxxxxxxxxx
URL:    http://www.shadowconnect.com
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