Re: [Qemu-devel] [PATCH 1/2] pc-dimm: No numa option shouldn't break hotplug memory feature

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 22 Sep 2014 14:17:28 +0300
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Fri, Sep 19, 2014 at 02:37:46PM +0200, Igor Mammedov wrote:
> > On Tue, 16 Sep 2014 18:39:15 +0800
> > zhanghailiang <zhang.zhanghailiang@huawei.com> wrote:
> > 
> > > If we do not configure numa option, memory hotplug should work as well.
> > > It should not depend on numa option.
> > > 
> > > Steps to reproduce:
> > > (1) Start VM: qemu-kvm -m 1024,slots=4,maxmem=8G
> > > (2) Hotplug memory
> > > It will fail and reports:
> > > "'DIMM property node has value 0' which exceeds the number of numa nodes: 0"
> > > 
> > > Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> > > ---
> > >  hw/mem/pc-dimm.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
> > > index 5bfc5b7..a800ea7 100644
> > > --- a/hw/mem/pc-dimm.c
> > > +++ b/hw/mem/pc-dimm.c
> > > @@ -252,7 +252,7 @@ static void pc_dimm_realize(DeviceState *dev, Error **errp)
> > >          error_setg(errp, "'" PC_DIMM_MEMDEV_PROP "' property is not set");
> > >          return;
> > >      }
> > > -    if (dimm->node >= nb_numa_nodes) {
> > > +    if ((nb_numa_nodes > 0) && (dimm->node >= nb_numa_nodes)) {
> > >          error_setg(errp, "'DIMM property " PC_DIMM_NODE_PROP " has value %"
> > >                     PRIu32 "' which exceeds the number of numa nodes: %d",
> > >                     dimm->node, nb_numa_nodes);
> > 
> > Reviewed-By: Igor Mammedov <imammedo@redhat.com>
> 
> 
> I read:
> > Hmm, I have just tested this, and Yes, it didn't work for Windows guest.
> > Thanks for your kind reminder.;)
> 
> So should I expect v2 which works with windows?
Hotplug wouldn't work with Windows without -numa (it's Windows limitation)
and more importantly pc-dimm shouldn't be limited only to NUMA configs
which this patch fixes.
This patch is fine and should go to stable as well.

On top of this we could add automatic NUMA node creation when
memory hotplug is enabled if this Windows workaround is acceptable.