[libvirt] exposing host-passthrough in virt-manager ui? (was: Re: [virt-tools-list] small suggestion)
On 2/6/19 10:57 AM, 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.
Possibly we could allow to set 'host-passthrough' as the default guest
CPU in virt-manager config.
Nowadays with host-model being much smarter, is there much functional
difference between host-model and host-passthrough? I don't really know
the answer.
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.
The problem I see is that host-passthrough sets the libvirt 'taint' flag
on the VM. While it doesn't have any real impact on end users generally
I took that to mean 'you are doing something that is unsupported'.
I don't personally don't have strong feelings against it but I've just
followed the advice I've been given here. Things have changed quite a
bit in the cpu config space in the past few years so maybe things are
different. changing subject and ccing libvir-list for wider audience
Thanks,
Cole