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Date: Tue, 18 May 2010 14:31:56 +0200
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/8] qdev: Allow device addressing
	via	'driver.instance'
References: <cover.1273843151.git.jan.kiszka@siemens.com>	<cover.1273843151.git.jan.kiszka@siemens.com>	<913f4f6a67305a72ed3d994bd12d5b34de9b9bb9.1273843151.git.jan.kiszka@siemens.com>
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To: Markus Armbruster <armbru@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, Juan Quintela <quintela@redhat.com>, Jan Kiszka <jan.kiszka@siemens.com>, qemu-devel@nongnu.org, Luiz Capitulino <lcapitulino@redhat.com>, Avi Kivity <avi@redhat.com>

On 05/18/10 14:15, Markus Armbruster wrote:
> Jan Kiszka<jan.kiszka@siemens.com>  writes:
>
>> Extend qbus_find_dev to allow addressing of devices without an unique id
>> via an optional instance number. The new formats are 'driver.instance'
>> and 'alias.instance'.
>>
>> Signed-off-by: Jan Kiszka<jan.kiszka@siemens.com>
>
> How's the instance number defined?  Should be documented.

savevm instance id, used to identify multiple instances of some device 
on loadvm.  By default is just incrementing (0,1,2,...) for each new 
device instance I think.  Drivers can also specify one.  Most don't do 
that.  IIRC some ISA drivers use the base ioport as instance id, which 
sort-of makes sense as it makes sure the id identifies the correct 
device no matter what the initialization order is.

It probably makes sense to replace the instance id with the device path 
once all devices are converted over to qdev+vmstate, so we avoid the 
nasty ordering issues altogether.

cheers,
   Gerd