Re: [PATCH 5 of 6] hotplug-memory: add section_ops

[Jeremy Fitzhardinge]

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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