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Date: Thu, 8 Oct 2009 19:11:57 +0200
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [Qemu-devel] Re: [PATCH v2 3/9] provide in-kernel ioapic
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To: Avi Kivity <avi@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, Glauber Costa <glommer@redhat.com>, kvm-devel <kvm@vger.kernel.org>, qemu-devel@nongnu.org

On Thu, Oct 08, 2009 at 06:42:07PM +0200, Avi Kivity wrote:
> On 10/08/2009 06:34 PM, Gleb Natapov wrote:
> >So suppose I have simple watchdog device that required to be poked every
> >second, otherwise it resets a computer. On migration we have to migrate
> >time elapsed since last poke, but if device doesn't expose it to
> >software in any way you are saying we can recreate is some other way?
> 
> The time is exposed (you can measure it by poking the device and
The time yes, not its internal representation. What if one implementation 
stores how much time passed and another how much time left. One counts
in wall clack another only when guest runs. etc... and this is a device
with only one write only register.

> measuring the time till reset) and will be described in the spec
> (otherwise users will be surprised when their machine resets).
> 
> You don't have to migrate all exposed state, just exposed state that
> the guest may rely on.

--
			Gleb.