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SubjectRe: [PATCH] iommu: moving initialization earlier
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On Fri, Jan 11, 2013 at 7:50 AM, Joerg Roedel <joro@8bytes.org> wrote:
> On Thu, Jan 10, 2013 at 01:40:17PM -0700, Shuah Khan wrote:
>> I am currently debugging IO_PAGE_FAULTS on 3.6.11 (happens on all
>> pre-3.7 releases). I root-caused the reason 3.7 works is because in
>> 3.7 amd iommu driver moving up the early iommu initialization from
>> irq_remap_ops with the irq remapping feature.
>
> Have you investigated the reason for those IO_PAGE_FAULTS? I guess they
> come from the USB controlers and happen between the time the IOMMU is
> enabled and the USB controlers are taken over by the Linux kernel from
> the BIOS.
>
> But I don't see why this patch can have any impact on the IO_PAGE_FAULTS
> you are seeing.

USB is one of them and SATA is another. I know with my back-port to
split dma ops initialization and this patch Alexey sent, the problem
goes away on 3.6.11 and I don't see the problem on 3.7. Same system,
and two different boots. I will investigate do more investigation into
the nature of these faults I am seeing and get back to you.

Thanks,
-- Shuah


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