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Re: [Xen-devel] S3 sleep in dom0 breaks dom0<->domU wallclock synchronization
On 07/05/10 21:18, Jeremy Fitzhardinge wrote: > On 07/01/2010 09:12 AM, Keir Fraser wrote: >> On 01/07/2010 16:18, "Joanna Rutkowska" <joanna@xxxxxxxxxxxxxxxxxxxxxx> >> wrote: >> >> >>> Actually we're running a pvops kernel in DomUs (in fact a fairly recent >>> pvops0, as we had some bad experience with regular Fedora kernels in DomU). >>> >>> Running an NTP in every VM is not a good solution. Some VMs might be >>> forbidden any access to the network (e.g. my "vault" VM, that I use for >>> storing passwords, and other very sensitive stuff, doesn't have any >>> networking), while some other might be allowed only very limited network >>> traffic, e.g. only HTTPS to specific, white-listed servers (e.g. >>> "banking" VM). >>> >> Well it would be good to confirm first that this is a pv_ops domU issue. If >> so, it can probably be solved with a command-line option or somesuch, even >> if the default policy will not change. >> > > So the problem is that dom0 does the S3 suspend/resume, and presumably > its wallclock time is updated properly via Linux's normal mechanisms. Yes. > But the S3 suspend/resume is unnoticed by all the domUs, so they don't > know that an enormous amount of time has passed in an instant? Correct. I don't think DomU are notified in any way about system suspend -- at least nothing is in the dmesg/messages logs. 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? > Does that affect all the guest clocks, or just wallclock? > Not sure if I understand your question -- what do you mean by "all guest clocks"? Like timers? They don't seem to be affected [*], as the apps run smoothly. joanna. [*] Except for when running on Core i5 -- see my other question in a different thread.
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