[virt-tools-list] small suggestion

Daniel P. Berrangé berrange at redhat.com
Wed Feb 6 16:32:15 UTC 2019

On Wed, Feb 06, 2019 at 04:57:17PM +0100, Pavel Hrdina wrote:
> On Wed, Feb 06, 2019 at 10:20:38AM -0500, Cole Robinson wrote:
> > On 2/5/19 6:19 PM, Hetz Ben Hamo wrote:
> > > Is it possible to add in the virt-manager the "host-passthrough" to the
> > > CPU models please?
> > > 
> > 
> > You can type 'host-passthrough' into the field and it will work. The reason
> > we don't advertise it is because it's considered to have some mild
> > supportability issues with libvirt. For the vast majority of use cases
> > though it's completely fine
> Maybe we can reconsider this decision, the only thing that would not
> work is live migration to destination with different CPU and we can
> have a warning/info about it in the UI.

NB, BIOS settings can affect migration safety too. In particular
the HT-enabled setting affects the number of performance counters
exposed to the guest.

> Possibly we could allow to set 'host-passthrough' as the default guest
> CPU in virt-manager config.
> Most workstation/desktop users of virt-manager probably doesn't care
> about live migration and it would copy the host CPU as closely as
> possible.  Since we allow to manually type in 'host-passthrough' I
> personally don't see any reason why it cannot be selectable.

I think we should allow it in virt-manager.  If we want protection
we should apply any check at time of live migration. 

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