[Qemu-devel] Re: [PATCH 1/8] qdev: Allow device addressing via 'driver.instance'

[Juan Quintela]

Gerd Hoffmann <address@hidden> wrote:
> On 05/18/10 14:15, Markus Armbruster wrote:
>> Jan Kiszka<address@hidden>  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<address@hidden>
>>
>> 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.

Agreed.  The problem here is that we sent the instance_id on the wire,
so for "legacy" devices that used an instance_id != -1, we are stuck
with it :(

Guess why a friend calls "backwards compatibility": A Curse of Bible
proportions :(

Later, Juan.