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Date: Tue, 9 Dec 2014 16:45:04 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 0/5] tpm: Extend the TPM TIS implementation
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To: Stefan Berger <stefanb@linux.vnet.ibm.com>
Cc: PeterHuewe@gmx.de, qemu-devel@nongnu.org

On Tue, Dec 09, 2014 at 09:40:28AM -0500, Stefan Berger wrote:
> On 12/09/2014 09:35 AM, Michael S. Tsirkin wrote:
> >On Tue, Dec 09, 2014 at 09:18:54AM -0500, Stefan Berger wrote:
> >>The following series of patches extends the TPM TIS implementation to
> >>version 1.3. This will lead to a TIS version that supports TPM 2.
> >>For this I would post relatively small patches afterwards.
> >>
> >>Regards,
> >>    Stefan
> >
> >Since this is guest visible, should this be limited
> >to new machine types, to avoid breaking migrating
> >guests across hypervisor versions?
> 
> Migration is not currently possible with TPM, since TPM (passthrough) is
> preventing it.
> 
>     Stefan

OK, for live migration, fair enough.

For off-line migration: will the following still work:
	- boot guest with tpm 1.3. use tpm in some way
	- halt, start guest on old qemu with tpm 1.2
?