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Date: Tue, 02 Nov 2010 11:43:32 +0100
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 06/40] qdev-ify: xen backends
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To: Markus Armbruster <armbru@redhat.com>
Cc: Alexander Graf <agraf@suse.de>, qemu-devel Developers <qemu-devel@nongnu.org>

On 11/02/10 11:08, Markus Armbruster wrote:
> Alexander Graf<agraf@suse.de>  writes:
>
>> From: Gerd Hoffmann<kraxel@redhat.com>
>>
>> This patch converts the xen backend code to qdev.
>
> qdev conversions are always welcome.  This one's not complete (search
> for #if 0).

It is a tricky one too.

Creating the xen backend device instances is controlled via xenstore 
(either emulated in case of xenner or xenstored when running on Xen). 
When creating block/net backends via qemu command line switches all qemu 
does is creating the xenstore entries.  Having a external entity (i.e. 
xend) creating the xenstore entries works too.

This workflow is a bit hard to fit into the qdev model ...

>> +    do {
>> +        done = 1;
>> +        QLIST_FOREACH(qdev,&xenbus->qbus.children, sibling) {
>> +            xendev = container_of(qdev, struct XenDevice, qdev);

[ ... ]

>> +            done = 0;
>> +            break;
>> +        }
>> +    } while (!done);
>
> This loop nest confuses me.  Why can't we just QLIST_FOREACH_SAFE()?

Just historical reasons I guess.  QLIST_FOREACH_SAFE() wasn't there from 
the start but got added later.

cheers,
   Gerd