Re: data corruption with nvidia chipsets and IDE/SATA drives (k8cpu errata needed?)

[Chip Coldwell]

On Thu, 18 Jan 2007, Andi Kleen wrote:
> The Northbridge guarantees coherency over the aperture, but
> only if the caching attributes match.

That's interesting.  Makes sense, I suppose.

> You would need to change_page_attr() every kernel address that is mapped into
> the  IOMMU to use an uncached aperture. AGP does this, but the frequency of
> mapping for the IOMMU  is much higher and it would be prohibitively costly
> unfortunately.

But it still might be a reasonable thing to do to test the theory that
the problem is cache coherency across the graphics aperture, even if
it isn't a long-term solution for the problem.

> In the past we saw corruptions from such conflicts, so this is more
> than just theory. I suspect you traded a more easy to trigger
> corruption with a more subtle one.

Yup.  That was the inspiration for the script.

Chip

--
Charles M. "Chip" Coldwell
Senior Software Engineer
Red Hat, Inc
978-392-2426

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