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xen-devel
Re: [Xen-devel] RE: Crashdump and IOMMU problems
At 23:11 +0100 on 11 May (1305155493), Kay, Allen M wrote:
> I believe Jan was involved with adding kexec support in iommu code.
>
> As for systematic way to disable active DMA, isn't this similar to OS
> shutdown case when all the drivers are unloaded? Does kexec unload all of
> the device drivers? Once all the drivers are unloaded, there shouldn't be
> any DMA transactions going on.
>
> I don't know much about kexec flow but it sound like the high level flow is:
> 1) dom0 kernel shutdown all of the device dirver and then 2) call
> iommu_ops->suspend() or crash_shutdown() to disable all of the iommu hardware.
>
In Xen we might have to kexec on crash without knowing even which VM is
driving the devices, so we can't do a clean unload. It might be
worthwhile just walking the PCI busses disabling everything, though.
Tim.
--
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd. (Company #02937203, SL9 0BG)
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