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    SubjectRe: [patch -mm 1/2] i386: add ptep_test_and_clear_{dirty,young}
    David Rientjes wrote:
    > On Sun, 25 Mar 2007, Zachary Amsden wrote:
    >> If you actually clear the bit, you need to:
    >> + pte_update_defer(vma->vm_mm, addr, ptep);
    >> The reason is, when updating PTEs, the hypervisor must be notified. Using
    >> atomic operations to do this is fine for all hypervisors I am aware of.
    >> However, for hypervisors which shadow page tables, if these PTE modifications
    >> are not trapped, you need a post-modification call to fulfill the update of
    >> the shadow page table.
    > Then why was ptep_test_and_clear_{dirty,young} ever removed in the first
    > place?? To gain the optimization of one fewer branch and introduce a hack
    > to advertise it's existance so the generic header file doesn't include its
    > own version?

    Yes, pretty much.

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      Last update: 2007-03-26 21:25    [W:0.038 / U:3.560 seconds]
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