Re: [Qemu-devel] [PATCH 07/12] target-i386: Add ICC_BUS and attach apic, kvmvapic and cpu to it

["Andreas Färber" <afaerber@suse.de>]

Am 28.03.2013 11:55, schrieb Igor Mammedov:
> On Wed, 27 Mar 2013 11:57:53 +0100
> Paolo Bonzini <pbonzini@redhat.com> wrote:
> 
>> Il 21/03/2013 15:28, Igor Mammedov ha scritto:  
>>> +static BusState *icc_bus;
>>> +
>>> +BusState *get_icc_bus(void)
>>> +{
>>> +    if (icc_bus == NULL) {
>>> +        icc_bus = g_malloc0(icc_bus_info.instance_size);
>>> +        qbus_create_inplace(icc_bus, TYPE_ICC_BUS, NULL, "icc-bus");
>>> +        icc_bus->allow_hotplug = 1;
>>> +        OBJECT(icc_bus)->free = g_free;  
>>
>> You can just use qbus_create.
>>   
>>> +        object_property_add_child(container_get(qdev_get_machine(),
>>> +                                                "/unattached"),  
>>
>> Please put it straight under /machine, not /unattached.  
> 
> sure
> 
>>
>> But actually, you lack a device that instantiates the bus.  That device
>> would be a simple container device similar hw/a15mpcore.c, and would  
> 
> About a year ago something like that device was proposed "cpu_sockets", but
> there was suggestion to drop it:
> http://lists.gnu.org/archive/html/qemu-devel/2012-02/msg02157.html
> So I've opted in favor of parent-less bus, but I could create it
> explicitly at board level as you suggest.
> 
> However having parent sysbus device for icc-bus will allow to see it via
> monitor info qtree

As I said on IRC, info qtree should not influence our design decisions.
All that's missing is a convenient script that pretty-prints the output
from the QOM graph using qom-list and qom-get in a non-interactive way.
Whether CPUs or busses are shown in info qtree is totally irrelevant IMO
by now.

> and reset on SysBus could be propagated through it as well,
> it may be good to add it later.

What exactly is this ICC bus needed for? Is it just a workaround for
qdev_init() or something making assumptions about busses and falling
back to SysBus otherwise? Or about avoiding SysBus?

And where would it sit if be hosted you think of something like Qseven
modules - on the board or on the module? I don't see pc.c being touched
here at all...

Andreas

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