Re: syncing wall clock time from Dom0 to hypervisor

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Jun 30, 2011 at 11:16:17AM +0100, Jan Beulich wrote:
> While in the upstream kernel I'm unable to find any use of XENPF_settime
> (and the DOM0_SETTIME alias of it) at all, in the 2.6.18 tree (and the
> forward ports of it) the function gets used only when ntp_synced()
> returns true (and - that's minor - when independent_wallclock is not
> set).
> 
> It would however seem to me that this doesn't cover the case where
> the host clock gets adjusted by the Dom0 admin. Is there perhaps
> someone who remembers whether this was implemented the way it
> is intentionally?

<groan> I think we just forgot.

Looking at xen_set_wallclock it just looks as we need to make it do
a similar hypercall as the sync_xen_wallclock to update it?

> 
> There's no such restriction in Jeremy's tree, but that tree also doesn't
> seem to be doing updates at regular intervals (for NTP), nor does it
> look like the CMOS clock would get updated here at all (i.e. I can't
> really take this as a proper reference either).

I think the 'sync_cmos_clock' looks to be doing that. And the hook
to the Xen is via 'update_persistent_clock' call?