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Date: Thu, 15 Sep 2011 10:28:52 -0500
From: Anthony Liguori <aliguori@us.ibm.com>
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Subject: Re: [Qemu-devel] [RFC] Plan for moving forward with QOM
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To: Gleb Natapov <gleb@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, Jan Kiszka <jan.kiszka@siemens.com>, qemu-devel <qemu-devel@nongnu.org>, Markus Armbruster <armbru@redhat.com>, Gerd Hoffmann <kraxel@redhat.com>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, Paolo Bonzini <pbonzini@redhat.com>

On 09/15/2011 09:25 AM, Gleb Natapov wrote:
> On Thu, Sep 15, 2011 at 04:14:45PM +0200, Paolo Bonzini wrote:
>> On 09/15/2011 03:57 PM, Anthony Liguori wrote:
>>>
>>> void generate_tree(Device *node)
>>> {
>>>     if (IS_PCI_BUS(node)) {
>>>        for (i = 0; i<  32; i++) {
>>>           generate_tree(lookup_device(get_property(node, "slot[%d]", i)));
>>>        }
>>>     } else if (IS_ISA_BUS(node)) {
>>>        ....
>>>     } else {
>>>        // leaf node, generate path segment
>>>     }
>>> }
>>>
>>> There are certainly ways to walk the graph generically (by coloring or
>>> following the composition paths) but that won't give you the desired
>>> ordering.
>>
>> It seems easier to go backwards from the target device.
> That what we do in qdev.
>
>>
>> Each device most likely will have a canonical parent link, and
>> together they will give the OF path.
>>
> Yeah, this canonical parent link should be marked somehow.

There is no canonical parent link.  A device may have multiple (more or less 
equivalent) parents.

What should be treated as the "canonical" link depends on what you're trying to 
do.  In the case of OF, you want to treat the bus as a parent.  If a device 
happens to sit on multiple buses, I'm not really sure what you do.

Regards,

Anthony Liguori

>
> --
> 			Gleb.
>