Re: [Qemu-devel] status of cpu hotplug work for x86_64?

[Vasilis Liaskovitis]

Hi,

On Mon, Apr 28, 2014 at 11:58:38AM -0600, Chris Friesen wrote:
> Hi,
> 
> I'm trying to figure out what the current status is for cpu hotplug
> and hot-remove on x86_64.
> 
> As far as I can tell, it seems like currently there is a QMP
> "cpu-add" command but no matching remove...is that correct?

correct. "cpu-add" is the way to hot-add CPUs.
There is no support for cpu hot-remove at this point. 

The latest patchset for cpu hot-remove that I know of is:
http://lists.gnu.org/archive/html/qemu-devel/2013-12/msg04266.html

If I understand correctly the biggest hurdle is supporting vcpu destruction
during the VM lifetime on the kvm host side. The corresponding kvm patches have
not been accepted:
http://comments.gmane.org/gmane.comp.emulators.kvm.devel/114347

So I have the same question as you: Is there any plan to support cpu hot-remove?

thanks,

- Vasilis