Re: [Qemu-devel] [PATCH v5 00/10] sPAPR CPU hotplug

[Christian Borntraeger]

On 11/23/2015 12:54 PM, Peter Krempa wrote:
> On Fri, Nov 20, 2015 at 18:24:29 +0530, Bharata B Rao wrote:
>> This patchset adds CPU hotplug support for sPAPR PowerPC guests using
>> device_add and device_del commands
>>
>> (qemu) device_add POWER8-powerpc64-cpu,id=cpu0
> 
> Is there a reason why this uses 'device_add' rather than the 'cpu_add'
> command? Libvirt uses two separate approaches already. Due to legacy
> reasons we support the HMP 'cpu_set' command, and lately we added
> support for QMP 'cpu-add'. Using device_add here will introduce a
> different approach and will require yet another compatibility layer in
> libvirt to support this.

s390 and powerpc both started with cpu_add patches. Andreas Faerber
suggested then to only implement device_add. This was apparently discussed
at the last KVM forum.

Christian