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Date: Wed, 20 Mar 2013 10:37:11 +0000
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Subject: Re: [Qemu-devel] [Xen-devel] [PATCHv3] QEMU(upstream): Disable
 xen's use of O_DIRECT by default as it results in crashes.
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To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>, Ian Jackson <Ian.Jackson@eu.citrix.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, xen-devel <xen-devel@lists.xen.org>, Alex Bligh <alex@alex.org.uk>, Anthony Liguori <anthony@codemonkey.ws>, Paolo Bonzini <pbonzini@redhat.com>

On 20/03/13 10:24, Stefano Stabellini wrote:
> That is true. My guess is that nobody really migrates HVM guests without
> PV drivers installed (it's not even possible on XenServer but xl let you
> do that if you want to). When the PV drivers initialize at boot time,
> the IDE disk is closed. Therefore we wouldn't have this problem.
>
> Maybe we should prevent HVM guest migration without PV drivers with xl
> too. Ian, what do you think?

We should be able to make it safe if we just make sure that qemu does a 
metadata sync / FS sync when we ask qemu to write the save file.

  -George