From: "Pavel Dovgaluk" <Pavel.Dovgaluk@ispras.ru>
References: <20140717110153.8352.80175.stgit@PASHA-ISP>	<20140717110255.8352.73575.stgit@PASHA-ISP>	<53D61AE3.6000700@redhat.com>
	<37740.9009532586$1406541296@news.gmane.org>
	<53D621F5.9050906@redhat.com>
In-Reply-To: <53D621F5.9050906@redhat.com>
Date: Wed, 30 Jul 2014 12:24:04 +0400
Message-ID: <000201cfabcf$a0568b40$e103a1c0$@Dovgaluk@ispras.ru>
MIME-Version: 1.0
Content-Type: text/plain;
	charset="utf-8"
Content-Transfer-Encoding: 7bit
Content-Language: ru
Subject: Re: [Qemu-devel] [RFC PATCH v2 10/49] rtl8139: adding new fields to
	vmstate
To: 'Paolo Bonzini' <pbonzini@redhat.com>, qemu-devel@nongnu.org
Cc: peter.maydell@linaro.org, peter.crosthwaite@xilinx.com, mark.burton@greensocs.com, real@ispras.ru, batuzovk@ispras.ru, fred.konrad@greensocs.com

> From: Paolo Bonzini [mailto:paolo.bonzini@gmail.com] On Behalf Of Paolo Bonzini
> Il 28/07/2014 11:54, Pavel Dovgaluk ha scritto:
> >>> > > +        VMSTATE_TIMER_V(timer, RTL8139State, 5),
> >> >
> >> > timer need not be migrated, because it is reinstated by rtl8139_post_load.
> >> >
> >   That's true for normal execution.
> >   In replay execution mode post_load can be called before cached virtual clock
> > values are loaded. This may cause invalid setting of the timer and raising
> > an IRQ which didn't happen in record mode.
> >   I will update this patch to fix post_load function and avoid this
> > non-deterministic behavior.
> 
> This is what worries me of this series.  These invariants are not
> documented anywhere, and people will break them unless you add
> assertions that also hold in normal mode.

Assertions is a good idea, we added such warning message to qemu_get_timedate function
to be sure, that it is used correctly with replay.

Another thing, that could help for making snapshots - find a way to load replay structures
before all other ones. Are there any priorities in migration states list?
Priorities could also solve some other issues, because sometimes post_load function
of one device uses other devices' functions. And the second ones could be not loaded yet.

Pavel Dovgalyuk