Re: question about MTRR areas on x86_64

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

Hello,

Eric W. Biederman wrote:
> 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.

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
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E-Mail: Markus.Lidel@shadowconnect.com
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