Re: [Xen-devel] Assigning contiguous memory to a driver domain

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

 On 09/20/2010 12:48 PM, Konrad Rzeszutek Wilk wrote:
> Let me expand this. During bootup Xen-SWIOTLB  (which for DomU you have
> to enable via the 'iommu=soft'), allocated 32 2MB chunks of contingous
> memory under the 4GB limit. Those chunks stay in DomU and are used
> during the the runtime of the DomU. They don't go back to Xen unless the
> domain has been terminated. Any of the DMA operations that any driver
> does go through the SWIOTLB bufer if the physical (mfn) for the DMA is
> outside the driver capabilities (say, your ping buffer is allocated above
> the 4GB, and your r8169 can only do 32-bit, then SWIOTLB would be utilized
> to "bounce" the memory).

BTW, are there any hooks to make sure these pages are still contiguous
after migration/restore?

    J

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