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SubjectRe: [PATCH 5 of 6] hotplug-memory: add section_ops
Christoph Lameter wrote:
> Note that you could use 4k page size chunks for the memmap if its
> virtualized (CONFIG_SPARSEMEM_VMEMMAP). Instead of a single PMD
> pointing to a 2MB block you would have the PMD point to a block of
> ptes that would in turn point to the discontiguous series of 4k pages.
>
> The memory is virtually contiguous so all the logic stays the same. What
> would be needed is some enhancements to the way the memmap is populated.

In Xen I think that would be accommodated by the existing
pseudo-physical to machine mapping. We don't support PSE anyway, so all
the pages would be individual 4k pages; the fact that they're
machine-discontigious is hidden because of the pseudo-phys to machine
mapping when ptes are constructed.

J


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