Re: [Qemu-devel] [RFC PATCH v4 00/11] sPAPR CPU hotplug

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

On Thu, Aug 06, 2015 at 04:42:05PM +0800, Zhu Guihua wrote:
> 
> On 08/06/2015 01:27 PM, Bharata B Rao wrote:
> >Hi,
> >
> >This is the next version of CPU hotplug support patchset for PowerPC
> >sPAPR guests. This is a split-out from the previous version (v3) that
> >was carrying CPU and memory hotplug together. This patchset applies on
> >spapr-next branch of David Gibson's tree.
> >
> >In the previous version, I was doing CPU addition at socket granularity.
> >One hotplug request would add one complete CPU socket with all the cores
> >and threads as per the boot time topology specification. Based on the
> >feedback for v3, I am switching back to earlier method wherein I don't
> >have the notion of socket device. In this version I don't create any
> >additional device abstraction over CPU device, but use the existing
> >CPU device and add full cores at once. One hotplug request will add
> >a complete core with all the underlying threads.
> 
> So the new generic infrastructure is generic socket or generic core?

In this implementation, it is neither, meaning it is not generic as you
can see from the device_add semantics at the end of this mail.

> 
> Cc: Andreas
> What about hot-adding a core device for x86 too?  Hot-plug per core seems to
> handle all cases.
> 
> thanks,
> Zhu
> 
> >I have enabled device_add based hotplug for POWER8 family for processors
> >and currently the semantics looks like this:
> >
> >(qemu) device_add POWER8-powerpc64-cpu,id=cpu8