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From: ebiederm@xmission.com (Eric W. Biederman)
To: Andi Kleen <ak@muc.de>
Cc: Markus Lidel <Markus.Lidel@shadowconnect.com>,
	linux-kernel@vger.kernel.org
Subject: Re: question about MTRR areas on x86_64
Date: 14 Oct 2004 04:49:16 -0600	[thread overview]
Message-ID: <m1acupefrn.fsf@ebiederm.dsl.xmission.com> (raw)
In-Reply-To: <m3vfdox14o.fsf@averell.firstfloor.org>

Andi Kleen <ak@muc.de> writes:

> Markus Lidel <Markus.Lidel@shadowconnect.com> 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.

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


That would be nice to see.

Eric

  reply	other threads:[~2004-10-14 10:52 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <2M5w2-y8-3@gated-at.bofh.it>
2004-10-05 22:15 ` question about MTRR areas on x86_64 Andi Kleen
2004-10-14 10:49   ` Eric W. Biederman [this message]
2004-10-14 14:04     ` Markus Lidel
2004-10-05 21:54 Markus Lidel

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