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Date: Wed, 20 Aug 2014 10:11:18 +0200
From: Michal Privoznik <mprivozn@redhat.com>
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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: Marcelo Tosatti <mtosatti@redhat.com>, Eric Blake <eblake@redhat.com>
Cc: libvir-list@redhat.com, qemu-devel <qemu-devel@nongnu.org>

On 19.08.2014 19:23, Marcelo Tosatti wrote:
> 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.
>

Okay then. I'm posting v3 here [1] which unconditionally calls the 
monitor command right after the guest agent command.

Michal

1: https://www.redhat.com/archives/libvir-list/2014-August/msg00867.html