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From: Eric Blake <eblake@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>,
	Michal Privoznik <mprivozn@redhat.com>
Cc: libvir-list@redhat.com, qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [libvirt] [PATCHv2 libvirt] qemu: Issue rtc-reset-reinjection command after guest-set-time
Date: Tue, 19 Aug 2014 11:00:26 -0600	[thread overview]
Message-ID: <53F382AA.5020405@redhat.com> (raw)
In-Reply-To: <20140819165713.GA4488@amt.cnet>

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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)?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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  reply	other threads:[~2014-08-19 17:00 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <075846faf30f2244fbaaf2c9f47cbae58a9524db.1408004697.git.mprivozn@redhat.com>
     [not found] ` <53F21B82.4050006@redhat.com>
2014-08-18 16:29   ` [Qemu-devel] [libvirt] [PATCHv2 libvirt] qemu: Issue rtc-reset-reinjection command after guest-set-time Michal Privoznik
2014-08-19 16:57     ` Marcelo Tosatti
2014-08-19 17:00       ` Eric Blake [this message]
2014-08-19 17:23         ` Marcelo Tosatti
2014-08-20  8:11           ` Michal Privoznik

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