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SubjectRe: [PATCHv3 0/6] Crashdump Accepting Active IOMMU
On 04/08/2014 12:14 PM, David Woodhouse wrote:
> On Mon, 2014-04-07 at 16:43 -0400, Don Dutile wrote:
>>
>> Additionally, a tidbit of information like "some servers force NMI's
>> on DMAR faults,
>> and cause a system reset, thereby, preventing a kdump to occur"
>> should have been included as one reason to stop DMAR faults from
>> occurring on kexec-boot,
>> in addition to the fact that a flood of them can lock up a system.
>
> How about allocating a physical scratch page, and setting up a mapping
> for each device such that *every* virtual address (apart from those
> listed in RMRRs, perhaps) is mapped to that same scratch page?
>
> That way you avoid the faults, but you also avoid stray DMA to parts of
> the system that you don't want to get corrupted.
>
+1... more isolation as second kernel booting sounds good.



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