On Fri, Jan 31, 2014 at 05:06:21PM +0100, Igor Mammedov wrote:
On Fri, 31 Jan 2014 13:17:53 -0200 Eduardo Habkost <ehabkost@redhat.com> wrote:
On Fri, Jan 31, 2014 at 03:50:23PM +0100, Paolo Bonzini wrote:
Il 31/01/2014 15:48, Igor Mammedov ha scritto:
that's abusing of object-add interface and due to recent changes, object-add won't accept arbitrary objects.
I hope that sooner or later device hotplug will be doable with object-add too. But yes, in the meanwhile device_add could work, and this patch series is in the right direction anyway.
In that case, what is holding us from setting cannot_instantiate_with_device_add_yet on TYPE_X86_CPU? I don't think we can recommend using "-device" for CPUs just yet, but we would need to allow it in case object-add doesn't work.
(But I liked the fact that object-add worked and (it looks like) it didn't run realize(). All libvirt needs is to be able to create the object and get instance_init() run, no need for realize() to run.)
I still need to read the reasoning behind the object-add changes. But is there some chance we could allow object-add to work for TYPE_X86_CPU subclasses, to avoid the device_add/cannot_instantiate_with_device_add_yet issues?
you can hack around by inheriting from UserCreatable interface, but question is what kind of information libvirt would expect from -object xxx-cpu
if it's going to read/interpret feature words then CPU.instance_init() is not sufficient, since properties (read as compat props) and realize() itself are changing feature words and CPU model guest is going to see is very different from what -object would create.
I am not sure yet, but maybe that's a good thing? I mean: libvirt has no concept of CPU models changing depending on machine-type yet, and this will be addressed later. In this case, not having the global properties set on the CPU object could be useful.
It looks like only -device would be able to create actual CPU models, but for -device to work we need as minimum this series and conversion of CPU features to properties in tree. Then I guess we can override cannot_instantiate_with_device_add_yet for x86 CPUs.
Setting cannot_instantiate_with_device_add_yet=false looks much simpler than implementing UserCreatable. My question is: may we do that, already (once this series gets included), or is there something else holding us from doing it? -- Eduardo