Re: [Qemu-devel] [PATCH 8/8] [PATCH RFC v2] s390-qemu: cpu hotplug - Treat S390 cpus as devices

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 29 Jul 2013 15:41:57 -0400
"Jason J. Herne" <jjherne@linux.vnet.ibm.com> wrote:

> On 06/08/2013 09:11 PM, Andreas Färber wrote:
> >>   if (tcg_enabled() && !inited) {
> >> >          inited = true;
> >> >          s390x_translate_init();
> >> >      }
> >> >+
> >> >+    smp_cpus += 1;
> > Won't we need some form of locking?
> >
> > If we fiddle with a global CPU counter, we should do so in qom/cpu.c,
> > not just in s390x code.
> >
> 
> I've redesigned a lot of this to make it simpler and less intrusive. 
> I'm almost ready to post the next revision but I'm hung up on this one 
> thing.
> 
> I moved the smp_cpu increment to qom/cpu.c : cpu_common_realizefn. 
> However this seems to break the user mode target because smp_cpus does 
> not exist.  I tried wrapping the increment in a #ifndef CONFIG_USER_ONLY 
> statement but it seems to have no effect.  I think the reason for that 
> is because CONFIG_USER_ONLY is added to config-target.h which is not 
> actually generated until after we compile qom/cpu.c.
> 
> ...
>    CC    qom/object.o
>    CC    qom/container.o
>    CC    qom/qom-qobject.o
>    CC    qom/cpu.o
>    CC    hw/core/qdev.o
>    CC    hw/core/qdev-properties.o
>    CC    hw/core/irq.o
>    GEN   s390x-linux-user/config-target.h
>    CC    s390x-linux-user/exec.o
> ...
> 
> Is there another place I should put the increment?

Could you just use current number of cpus instead of smp_cpus increment?