From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: Re: S3 sleep in dom0 breaks dom0<->domU wallclock synchronization Date: Tue, 06 Jul 2010 11:02:40 +0100 Message-ID: <4C331B600200007800009B4F@vpn.id2.novell.com> References: <4C32F320.3060103@invisiblethingslab.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <4C32F320.3060103@invisiblethingslab.com> Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser , Joanna Rutkowska Cc: Jeremy Fitzhardinge , Jeremy Fitzhardinge , "xen-devel@lists.xensource.com" , Rafal Wojtczuk , Konrad Rzeszutek Wilk List-Id: xen-devel@lists.xenproject.org >>> On 06.07.10 at 11:10, Joanna Rutkowska = wrote: > On 07/06/10 05:52, Keir Fraser wrote: >> On 05/07/2010 23:50, "Jeremy Fitzhardinge" wrote: >>=20 >>>> BTW: wouldn't it be good to actually notify them? Consider e.g. DomU >>>> that has some device assigned to it (say a NIC) -- if we emulated S3 >>>> suspend/resume for this DomU, there is a hope it would properly >>>> suspend/reinitialize the NIC, wouldn't it? >>>> =20 >>> >>> I guess? That implies some kind of PV S3 suspend and resume event to >>> feed into the dom U's device model. What does 2.6.18-xen do? >>=20 >> I don't think our S3 support is very compatible with PV device = passthrough. >> We support HVM virtual S3, and can S3-sleep HVM guests across real host = S3, >> but we don't have similar for PV guests. >>=20 >=20 > How about implementing something very simple, like a notification via > xenstore (say, Dom0 would be setting some key)? Interested DomUs could > then register a watch, and get notified when the system was resumed from > S3. This would let them e.g. to call whatever hypercall is used normally > on DomU boot to sync DomU wallclock, or reinitialize/reconnect the NIC. Wouldn't it be much simpler to not introduce any new logic at all and just let Dom0 tools/scripts take care of properly suspending (checkpointing) all (minimally all pv, but I would really think treating different kinds of guests differently here is unnecessary) guests before doing a host suspend, as Jeremy had suggested in an earlier reply? Jan