Re: [Qemu-devel] [RFC PATCH v2 0/9] Core based CPU hotplug for PowerPC sPAPR

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

On Mon, Mar 14, 2016 at 10:47:28AM +0100, Igor Mammedov wrote:
> On Fri, 11 Mar 2016 10:24:29 +0530
> Bharata B Rao <bharata@linux.vnet.ibm.com> wrote:
> 
> > Hi,
> > 
> > This is the next version of "Core based CPU hotplug for PowerPC sPAPR" that
> > was posted at
> > https://lists.gnu.org/archive/html/qemu-ppc/2016-03/msg00081.html
> > 
> > device_add semantics
> > --------------------
> > For -smp 16,sockets=1,cores=2,threads=8,maxcpus=32
> > (qemu) device_add spapr-cpu-core,id=core2,core=16,cpu_model=host[,threads=8]
> do you plan to allow user to hotplug different cpu_models?
> If not it would be better to hide cpu_model from user
> and set it from machine pre_plug handler.

In my earlier implementations I derived cpu model from -cpu and threads from
-smp,threads= commandline options and never exposed them to device_add
command.

Though we don't support heterogenous systems (different cpu models and/or
threads) now, it was felt that it should be easy enough to support such
systems if required in future, that's how cpu_model and threads became
options for device_add.

One of the things that David felt was missing from my earlier QMP query
command (and which is true in your QMP query implementation also) is that
we aren't exporting cpu_model at all, at least for not-yet-plugged cores.
So should we include that or let management figure that out since it
would already know about the CPU model.

Regards,
Bharata.