Messages in this thread | | | Date | Thu, 18 Sep 2008 15:18:26 -0700 | From | Jeremy Fitzhardinge <> | Subject | Re: Populating multiple ptes at fault time |
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Avi Kivity wrote: >> Do you need to set the A bit synchronously? > > Yes, of course (if no guest cooperation).
Is the A bit architecturally guaranteed to be synchronously set? Can speculative accesses set it? SDM vol 3 is a bit vague about it.
> I'll fail my own unit tests. > > If we add an async mode for guests that can cope, maybe this is > workable. I guess this is what you're suggesting. >
Yes. At worst Linux would underestimate the process RSS a bit (depending on how many unsynchronized ptes you leave lying around). I bet there's an appropriate pvop hook you could use to force synchronization just before the kernel actually inspects the bits (leaving lazy mode sounds good).
J
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