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Date: Thu, 09 Jul 2009 08:45:19 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] [PATCH 2/3] move vm stop/start to migrate_set_state
References: <1247140059-5034-1-git-send-email-pbonzini@redhat.com>
	<1247140059-5034-3-git-send-email-pbonzini@redhat.com>
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org

Paolo Bonzini wrote:
> With this patch, the state machine grows a new state, COMPLETING.
> This new state corresponds to the VM being stopped while migration
> is finalized.  Stopping and starting the machine is driven
> exclusively by the state machine mechanisms.
>
> Two rare bugs are fixed.  The first is a race; the VM used to remain
> stopped if a migration was canceled exactly in what corresponds
> to the new COMPLETING state.

You cannot cancel during the stopped state.  When you enter into the 
final stage, you no longer process monitor input.

>   A bit worse is that if an error occurred
> exactly during the final stage (for example due to disk full)
> the VM was unconditionally restarted, even if it was paused before
> the beginning of the migration.
>   

How does the disk become full during the final stage?  The guest isn't 
running.

Regards,

Anthony Liguori