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Date: Tue, 20 Sep 2011 08:36:14 +0200
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 04/14] qdev: take ownership of id pointer
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Peter Maydell <peter.maydell@linaro.org>, Anthony Liguori <aliguori@us.ibm.com>, Jan Kiszka <jan.kiszka@siemens.com>, qemu-devel@nongnu.org, Markus Armbruster <armbru@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>

On 09/19/11 18:27, Anthony Liguori wrote:
> On 09/19/2011 02:34 AM, Gerd Hoffmann wrote:
>> FYI: Keeping the pointer to the QemuOpts has one more reason: It will
>> free the
>> QemuOpts on hot-unplug, which is needed to free the id from QemuOpts
>> point of
>> view, which in turn allows to re-use the id when hot-plugging the same
>> (or
>> another) device later on.
>
> You mean, tie QemuOpts life cycle to devices life cycle

Yes.

> such that you
> cannot accidentally create a non-device QemuOpts that conflicts with the
> id of a device?

Device QemuOpts have their own id namespace, so this is just about 
conflicts within devices.  This ...

    device_add e1000,id=nic1
    device_del nic1
    device_add e1000,id=nic1

... will work only if you free the QemuOpts when deleting a device, 
otherwise QemuOpts will complain that nic1 is used already.

cheers,
   Gerd