[PATCH retry] intel-iommu:make identity_map default for crash dump

Dave Young dyoung at redhat.com
Tue Nov 1 05:52:28 EDT 2011

On 11/01/2011 05:34 PM, David Woodhouse wrote:

> On Tue, 2011-11-01 at 17:19 +0800, Dave Young wrote:
>> kdump kernel sometimes will get DMAR faults which
>> is caused by random in-flight dma from 1st kernel
>> Here make the identity_mapping as default for this case
> So you want to *allow* the random in-flight DMA? And with an identity
> mapping it's really going to random addresses, since it'll be
> untranslated and won't even go to the physical addresses which it was
> originally intended for?
> This seems entirely broken to me.
> If there is "random in-flight dma" from the first kernel, the correct
> thing to do is *block* it. Which is what we do.

This patch works for me for several cases. For kdump It can be seen a
workaround. But yes blocking the 1st kernel dma is ideal.

Glad to hear that you are working on this.


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