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xen-devel
RE: [Xen-devel] [PATCH] Fix hvm time issue.
> >Do RTC and HPET need to be included as periodic timers? They are
never
> used
> >by Linux for ticks (it always uses PIT for jiffy updates) and I think
> >Windows is more robust against (or at least doesn't noticeably
complain
> >about) time jumps.
> >
>
> For RTC, yes! As we know some version of Windows uses RTC as main time
> resource for timekeeping.
I suspect that it only does this because during boot it decides that it
doesn't like the look of our pm_timer (I don't blame it!)
It would be good to invest some effort understanding why it selects RTC
-- I'm sure that it's a fall back.
Ian
We noticed if it's not added as periodic
> timer, Windows time may go slow in SMP environment.
> In case of HPET, the answer may be no, as OS can read the
monotonically
> increased counter to see time jumps.
>
> And as periodic timer list is per vcpu, it's also helpful to sync one
> vcpu's lapic time with its TSC, which is needed when guest calibrates
> lapic at least.
>
> Thanks,
> Xiaowei
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
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