Re: [Qemu-devel] [RFC/PATCH 0/1] cpu hotplug for s390

[Jens Freimann <jfrei@linux.vnet.ibm.com>]

On Wed, Apr 17, 2013 at 08:06:37PM +0200, Andreas Färber wrote:
> Hi Jens,
> 
> Am 03.04.2013 08:42, schrieb Jens Freimann:
> > this is what our approach to CPU hotplug looks like.
> > With respect to Igor's CPU hotplug series, how should we proceed? 
> > Should we change the interface to 
> > qemu_system_cpu_add_notifier/qemu_system_cpu_hotplug_request/cpu-add etc?
> 
> I am wondering if my recent qdev/device_add fixes would allow to
> implement CPU hot-add via device_add for s390x?

>From what I've seen so far it could be possible, but...
 
> Background is that for x86 we currently have a flat CPU core/thread
> namespace but would need to deal with sockets, cores and threads to get
> topologies right. I assume there are no such issues on s390x, so that
> the vCPU to CPUState mapping could stay 1:1?

s390 hardware today already has a topology and CPU features.  We are not 
modelling it in QEMU right now, but want to go there in the future so that 
there would be no simple 1:1 mapping anymore.
 
> > Feedback regarding the non-API part is also highly welcome!
> 
> I did spot some QOM'ish nitpicks in the qdev_create() but I am wondering
> if you and Alex see an urgent need to get this into 1.5 during the Soft
> Freeze or whether we can just align it to x86 work for now and deal with
> it after the release?

We'll try to have it ready as soon as possible but I think it's unlikely
for 1.5. Getting started with Igor's review feedback right now and looking
at qdev_create() as well. 


Regards,
Jens
 
> Regards,
> Andreas
> 
> > Thang Pham (1):
> >   s390: implement CPU hotplug
> > 
> >  hmp-commands.hx           |  14 +++++
> >  hw/s390x/Makefile.objs    |   2 +-
> >  hw/s390x/event-facility.c |   9 ++++
> >  hw/s390x/event-facility.h |   3 ++
> >  hw/s390x/s390-virtio.c    |  34 +++++++++---
> >  hw/s390x/sclp.c           | 134 +++++++++++++++++++++++++++++++++++++++++++++-
> >  hw/s390x/sclp.h           |  47 +++++++++++++++-
> >  include/sysemu/sysemu.h   |   1 +
> >  monitor.c                 |  31 +++++++++++
> >  target-s390x/cpu.c        |  59 ++++++++++++++++++++
> >  target-s390x/cpu.h        |   7 +++
> >  target-s390x/helper.c     |  43 +++++++++++++++
> >  vl.c                      |   6 +++
> >  13 files changed, 379 insertions(+), 11 deletions(-)
> > 
> 
> 
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