Re: [Qemu-devel] [Qemu-ppc] [PATCH: RFC] Adding BAR0 for e500 PCI controller

["Andreas Färber" <afaerber@suse.de>]

Am 07.09.2012 20:58, schrieb Scott Wood:
> On 09/07/2012 03:08 AM, Alexander Graf wrote:
>>
>> On 07.09.2012, at 01:15, Scott Wood <scottwood@freescale.com> wrote:
>>
>>> On 09/03/2012 01:44 AM, Bhushan Bharat-R65777 wrote:
>>>>
>>>> Can we somehow pass this via qdev/varargs from machine emulation code
>>>> (hw/ppc/e500.c) ?
>>>
>>> Possibly, though it may not be the best idea to express every single
>>> aspect of intercomponent integration via qdev -- maybe that's best left
>>> for things that are reasonably user-tweakable.  If CCSR size is user
>>> tweakable, it would be somewhere other than the PCI controller.
>>
>> It depends. Qdev properties are basically object constructor
>> parameters. So if you were weiting C++ code and would have a
>> constructor that gets the size as argument, it would end up being
>> modeled as qdev property.
>>
>> If however actual functionality differs, thus you would in OO speech
>> create a subclass / child class, then you are better off creating a
>> new device struct.
>>
>> In this case, I'm not sure. They are different devices really, but
>> are close enough that the differences could be expressed through qdev
>> properties.
> 
> I wasn't suggesting that they be different devices.  I was suggesting
> that this isn't a property of the PCI controller, but rather of some
> other entity to which the PCI controller connects.  So maybe a reference
> to the associated CCSR object would be a qdev parameter, but not the
> size of that CCSR.

For a reference to another object a QOM link<> property would be
preferred over a static qdev property.

Andreas

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