On 14/01/2010 08:38, "Cui, Dexuan" <dexuan.cui@xxxxxxxxx> wrote:
> Currently PERCPU_SIZE is 2 4K-pages and only 1 page is used actually.
>
> From xen 20209 on, the second unused page is freed and returned to domheap in
> debug=n build (MEMORY_GUARD is not defined):
> percpu_free_unused_areas() -> free_xen_data() -> init_xenheap_pages().
> Later the returned pages could be allocated to dom0 and dom0 could use them as
> DMA buffer.
>
> However, in iommu_set_dom0_mapping(), xen_in_range() is still True for the
> freed pages above, so devices in Dom0 can meet with DMA fault.
Should be fixed by c/s 20803.
 Thanks,
 Keir
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