Re: [Qemu-devel] [PATCH V13 6/7] Introduce --enable-tpm-passthrough configure option

[Anthony Liguori]

On 12/13/2011 07:51 AM, Michael S. Tsirkin wrote:
> On Tue, Dec 13, 2011 at 07:51:17AM -0500, Stefan Berger wrote:
> > On 12/12/2011 11:51 PM, Paul Brook wrote:
> > > > > > +tpm_passthrough="no"
> > > > > Same as before, please probe for existence.
> > > > We would be probing for /dev/tpm0. Is that really what we want that this
> > > > driver only gets compiled if /dev/tpm0 is (currently) available?
> > > If what you say is true then this code should always be enabled.
> > Michael Tsirkin previously requested that there be an option for the
> > TPM passthrough driver to be selectively enabled since at least
> > using /dev/tpm0 may not be what everybody wants. The passthrough
> > driver at some point will also be able to use sockets to communicate
> > with a TPM when a file descriptor is passed to Qemu, so maybe that
> > changes then?
> >
> >
> >     Stefan
>
> The passthrough as it is, is pretty easy to misuse.
> This is a hardware problem, not software, and
> I don't think it's fixable.

Can you elaborate?  And can this be documented such that users are aware of 
this.

Regards,

Anthony Liguori

> So I do not think all downstreams will want to support this
> mode, making it easy to disable this is IMO important.