Re: [Qemu-devel] [PATCH 1/7] Introduce a new bus "ICC" to connect APIC

[Anthony Liguori]

On 02/16/2012 05:25 AM, Jan Kiszka wrote:
> On 2012-02-16 00:16, Igor Mammedov wrote:
> > Introduce a new structure CPUS as the controller of ICC (INTERRUPT
> > CONTROLLER COMMUNICATIONS), and new bus "ICC" to hold APIC,instead
> > of sysbus. So we can support APIC hot-plug feature.
> >
> > This is repost of original patch for qemu-kvm rebased on current qemu:
> > http://lists.nongnu.org/archive/html/qemu-devel/2011-11/msg01478.html
> > All credits to Liu Ping Fan for writing it.
> >
> > V2 changes:
> >    - cpusockets_init: cpu_sockets is not yet initialized, use cpus that
> >      we got as input param instead for qbus_create, this makes cpus
> >      apics visible in "info qtree" monitor command
> >    - fix format error spotted by Jan and missed by checkpatch
> >    - cpu_has_apic_feature: return bool instead of int
>
> This patch surely no longer applies. And the ICC requires QOM conversion.

Also, post-QOM, I don't think having an ICC bus makes a whole lot of sense.

The LAPIC can be made a child of the CPU device with a bidirectional link.

I would simply create a fixed set of CPU links<> hung off of /devices somewhere 
and use that as the hotplug mechanism.  This matches well the way we model this 
to the guest (we expose a fixed number of pluggable sockets).

Regards,

Anthony Liguori

> Jan