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Date: Thu, 01 Dec 2011 09:14:11 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH 07/18] qom: add link properties
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To: Gerd Hoffmann <kraxel@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>, Jan Kiszka <jan.kiszka@siemens.com>, qemu-devel@nongnu.org, Markus Armbruster <armbru@redhat.com>, Avi Kivity <avi@redhat.com>, Luiz Capitulino <lcapitulino@redhat.com>

On 12/01/2011 09:03 AM, Gerd Hoffmann wrote:
>    Hi,
>
>> In terms of QMP client code, you just do:
>>
>>   qom-set /path/to/usb-controller.slave /some/other/device
>
> Lacks notification.  usb-controller doesn't notice that you have plugged
> in some usb device and thus can't raise an IRQ to notify the guest ...

Properties will have flags.  One of those flags makes the property mutable only 
while the device isn't realized.

This is a case where the property is mutable during realize.  You wouldn't use a 
normal link here.  You would use a "hotpluggable link" which would have a notify 
hook.

This works because all properties are get/set through an accessor interface and 
there's a rich error interface.

The original QOM series I posted had this logic in it.

Regards,

Anthony Liguori

>
> cheers,
>    Gerd
>
>