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Date: Tue, 19 Aug 2014 14:23:24 -0300
From: Marcelo Tosatti <mtosatti@redhat.com>
Message-ID: <20140819172324.GA5717@amt.cnet>
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Subject: Re: [Qemu-devel] [libvirt] [PATCHv2 libvirt] qemu: Issue
 rtc-reset-reinjection command after guest-set-time
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To: Eric Blake <eblake@redhat.com>
Cc: libvir-list@redhat.com, Michal Privoznik <mprivozn@redhat.com>, qemu-devel <qemu-devel@nongnu.org>

On Tue, Aug 19, 2014 at 11:00:26AM -0600, Eric Blake wrote:
> On 08/19/2014 10:57 AM, Marcelo Tosatti wrote:
> > 
> > rtc-reset-reinjection has been introduced because certain Windows
> > versions will advance the guest system time (via rtc interrupt
> > reinjection).
> > 
> > So if libvirt adjusts the guest system time via guest-set-time, 
> > allowing rtc interrupt reinjection to compensate for lost time, 
> > as well, will cause an incorrect guest system time.
> > 
> > So you should always use the 
> > 
> >     guest-set-time
> >     rtc-reset-reinjection
> > 
> > pair.
> 
> But is that true both for the 'guest-set-time' no-arg case (which tells
> the guest to read the current RTC and update in-memory time
> accordingly), as well as the 'guest-set-time with time argument' case
> (which tells the guest to forcefully set in-memory time, then write that
> time back to the RTC)?

Yes.