This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] syncing wall clock time from Dom0 to hypervisor

To: Jan Beulich <JBeulich@xxxxxxxxxx>
Subject: Re: [Xen-devel] syncing wall clock time from Dom0 to hypervisor
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Wed, 13 Jul 2011 09:52:35 -0400
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Wed, 13 Jul 2011 06:53:20 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <4E0C6911020000780004B45B@xxxxxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <4E0C6911020000780004B45B@xxxxxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.5.21 (2010-09-15)
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?

Xen-devel mailing list

<Prev in Thread] Current Thread [Next in Thread>