Re: [patch -mm 1/2] i386: add ptep_test_and_clear_{dirty,young}

[Hugh Dickins <hugh@veritas.com>]

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.

Thanks for the very rapid response.

So, David just needs to move the pte_update_defer out of
ptep_clear_flush_* and into ptep_test_and_clear_*?

That leaves me wondering why you deleted ptep_test_and_clear_*
(while leaving their __HAVE_ARCHes) in the first place?

Hugh