Re: [Qemu-devel] change x86 default machine type to Q35?

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Daniel P. Berrange (berrange@redhat.com) wrote:
> On Thu, Jul 06, 2017 at 01:00:53PM +0200, Thomas Huth wrote:
> > On 06.07.2017 12:49, Daniel P. Berrange wrote:
> > [...]
> > > This avoids the user having problems with guest ABI silently changing
> > > behind their back, or migration suddenly failing to load vm state,
> > 
> > For proper migration, you've got to specify the right versioned machine
> > type anyway, so that should not be an issue here.
> 
> That's only true if you have mis-matched QEMU releases on each host.
> If you know you have the same QEMU release everywhere, there's no
> need for versioned machine types. Though obviously we'd still recommend
> people us versioned machine type, its not unreasonable that some people
> will not

We have got protection against machine type screwups; e.g going from -M
pc to -M q35 we get:

qemu-system-x86_64: Machine type received is 'pc-i440fx-2.9' and local is 'pc-q35-2.9'

Dave

> Regards,
> Daniel
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Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK