Re: [Qemu-devel] [PATCH qom-next 4/6] pc: move apic_mapped initialization into common apic init code

[Andreas Färber]

Am 24.05.2012 15:10, schrieb Igor Mammedov:
> On 05/23/2012 11:26 PM, Peter Maydell wrote:
>> On 23 May 2012 22:09, Igor Mammedov<address@hidden>  wrote:
>>> For cpu-hotplug it was suggested to use device_add/del
>>> interface for it. To do so in a generalized way hot-plugged cpu
>>> should follow general QOM object creation sequence, i.e.
>>>   - create new cpu instance
>>>   - set properties
>>>   - realize instance
>>> without creating precedent of special case for cpus in device_add/del
>>> if possible. So goal is to have a self-sufficient cpu object that
>>> doesn't require external hooks to create/initialize it. It looks
>>> possible do so for target-i386 at least.
>>
>> I think your self-sufficient CPU object should probably be a
>> container QOM object which contains the CPU core itself and
>> the APIC device. Then the container object's initialisation
>> can map the APIC device.
> 
> For x86 it would be artificial thing without a real hardware to
> model after, that would needlessly complicate code and interface.
> I'd rather avoid this.
> 
> Meanwhile I've found only two devices that do mapping inside
> device's initfn :(
> 
> hw/lm32_sys.c
> hw/bonito.c
> 
> and lm32_sys has comment:
>     /* Note: This device is not created in the board initialization,
>      * instead it has to be added with the -device parameter. Therefore,
>      * the device maps itself. */
> 
> So for some devices it's possible to do so.

Simply put: Doing the mmio_map after qdev init is historical and no
reason to keep doing so. It breaks the desired late-realize model.

I believe Anthony's controversial series on GitHub with the
"boilerplate" accessors that Peter so disliked tried to fix this?

Andreas

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg