On Fri, 28 Jun 2013, David Vrabel wrote:
>
> Before:
>
> Xen wallclock set when time is stepped.
> Xen wallclock set every 11 minutes (by sync_cmos_clock()).
> Hardware RTC never set.
>
> After:
>
> Xen wallclock set when time is stepped.
> Xen wallclock set every 11 minutes (in pvclock gtod notifier).
Ah, you are emulating the sync_cmos_clock() behaviour for the xen
wallclock via the periodic pvclock_gtod notifier call.
> Hardware RTC set every 11 minutes (by sync_cmos_clock()).
>
> I'll update the changelog to be more descriptive:
>
> Adjustments to Xen's persistent clock via update_persistent_clock()
> don't actually persist, as the Xen wallclock is a software only clock
> and modifications to it do not modify the underlying CMOS RTC.
>
> The x86_platform.set_wallclock hook can be used to keep the hardware
> RTC synchronized (as on bare metal). If (in dom0) we make the Xen
> wallclock periodically synchronized by the pvclock_gtod notifier, the
> set_wallclock hook need not update the Xen wallclock and the native
> implementation can be used.
Yep. I'll pick that up.
Thanks,
tglx
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