Re: [Qemu-devel] [PATCH 12/12] target-i386: implement CPU hot-add

[Eduardo Habkost]

On Wed, Apr 03, 2013 at 07:58:00PM +0200, Igor Mammedov wrote:
<snip>
> > > +void do_cpu_hot_add(const int64_t id, Error **errp)
> > > +{
> > > +    pc_new_cpu(saved_cpu_model, id, errp);
> > > +}
> > > +
> > 
> > Missing x86_cpu_apic_id_from_index(id)?
> There was(is?) opposition to using cpu_index to identify x86 CPU.

Really? Do you have a pointer to the discussion?


> So, it is expected from management to provide APIC ID instead of cpu_index.
> It could be useful to make hotplug to a specific NUMA node/cpu to work in
> future.
> Though interface of possible APIC IDs discovery is not part of this series.

That's exactly the opposite of what I expect. The APIC ID is an internal
implementation detail, and external tools must _not_ be required to deal
with it and to calculate it.

Communication with the BIOS, on the other hand, is entirely based on the
APIC ID, and not CPU indexes. So QEMU needs to translate the CPU indexes
(used to communicate with the outside world) to APIC IDs when talking to
the BIOS.

-- 
Eduardo