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Date: Tue, 30 Jun 2009 15:36:09 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] [PATCH 4/8] qdev/core: bus list
References: <1246353962-32308-1-git-send-email-kraxel@redhat.com>	<200906301218.35086.paul@codesourcery.com>	<87k52t8xvk.fsf@pike.pond.sub.org>	<200906301821.18245.paul@codesourcery.com>
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To: Gerd Hoffmann <kraxel@redhat.com>
Cc: qemu-devel@nongnu.org, Markus Armbruster <armbru@redhat.com>, Paul Brook <paul@codesourcery.com>

Gerd Hoffmann wrote:
> On 06/30/09 21:49, Anthony Liguori wrote:
>> I think it's a perfectly valid suggestion that we should identify buses
>> based on the their location in the tree to users verses a number
>> generated based on some hashing algorithm.
> >
>> A tree location has meaning to a user. A random integer doesn't.
>
> Well.  Depends on the bus I think.  About PCI devices the usual user 
> probably thinks in terms of "$bus:$slot.$function", which includes a 
> bus number.

But if you think of SCSI as a bus, then it makes more sense to enumerate 
each SCSI bus by the tree location (which would end up being the PCI 
location) than a made up number.

> Speaking of PCI: the PCI bus number (aka PCIBus->bus_num) has nothing 
> to do with the more or less random bus number introduced by the (now 
> dropped) patch (aka PCIBus->qdev.busnr).

Yup.

> Which indicates that it is probably less confusing to have the bus 
> implementation handle the enumeration of busses.  If it makes sense 
> for the bus in question of course.  sysbus probably doesn't care ;)

That's probably a good point.

Regards,

Anthony Liguori