Messages in this thread | | | Date | Wed, 21 Aug 2013 18:12:23 +0400 | From | Cyrill Gorcunov <> | Subject | Re: Regression: x86/mm: new _PTE_SWP_SOFT_DIRTY bit conflicts with existing use |
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On Wed, Aug 21, 2013 at 02:48:20PM +0100, David Vrabel wrote: > All, > > 179ef71c (mm: save soft-dirty bits on swapped pages) introduces a new > PTE bit on x86 _PTE_SWP_SOFT_DIRTY which has the same value as _PTE_PSE > and _PTE_PAT. > > With a Xen PV guest, the use of the _PTE_PAT will result in the page > having unexpected cachability which will introduce a range of subtle > performance and correctness issues. Xen programs the entry 4 in the PAT > table with WC so a page that was previously WB will end up as WC. >
David, could you please explain, Xen keeps and analyze _PTE_PAT bit for ptes which are not present?
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