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Date: Thu, 15 Sep 2011 18:38:38 +0300
From: Gleb Natapov <gleb@redhat.com>
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Subject: Re: [Qemu-devel] [RFC] Plan for moving forward with QOM
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To: Anthony Liguori <aliguori@us.ibm.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 Thu, Sep 15, 2011 at 10:28:52AM -0500, Anthony Liguori wrote:
> 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.
> 
Yes, "canonical" is a link to a bus. Can you give an example of a device
that sits on multiple buses?

--
			Gleb.