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Date: Wed, 08 Jun 2011 19:00:40 +0200
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] inconsistency between device traversal in qdev and
 legacy
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: QEMU Developers <qemu-devel@nongnu.org>, Markus Armbruster <armbru@redhat.com>

   Hi,

> Since qbus_create_inplace() adds each new child bus to
> the front of the parent's child_bus list, this means that
> qbus_find_recursive() will encounter the last-added bus
> first, whereas usb_bus_find() will get the first-added bus.

Quite a while back I've tried to switch qdev from QLIST to QTAILQ 
exactly to allow adding stuff to the tail of the lists(s), because that 
feels more natural to me than the current ordering.  "info qtree" is 
upside-down too ;)

Gave up after resending it one or two times, the forgot about it, wasn't 
*that* important to me.

> Is there anything we can do to fix this inconsistency [*],
> or are we tied to the existing enumeration orders in both
> cases for compatibility with users with currently-working
> command lines or configurations?

Could be we break something.  I think it is unlikely though.  Multiple 
busses of the same type are pretty uncommon, and any examples with 
multiple lsi adapters (for example) advertise explicitly assign devices 
via bus=.  libvirt uses bus= everywhere too.

cheers,
   Gerd