Re: [Qemu-devel] [PATCH v1 1/3] qdev: Expose the qdev id string as a prop

[Markus Armbruster]

Peter Crosthwaite <address@hidden> writes:

> On Wed, Apr 16, 2014 at 2:16 AM, Andreas Färber <address@hidden> wrote:
>> Am 15.04.2014 04:21, schrieb Peter Crosthwaite:
>>> So clients can set the top level id string.
>>>
>>> Signed-off-by: Peter Crosthwaite <address@hidden>
>>
>> Anthony had nack'ed Paolo's attempt to generalize the qdev id to QOM, so
>> I'm not sure if we should really do this even if just on device level.
>> The id= is used to construct the canonical path, and we can't change
>> that through a qdev setter.

Let me try to paraphrase to make sure I got you: The canonical QOM path
is fixed at creation time.  Setting an ID dynamically would destroy the
relationship between ID and canonical QOM path.  Correct?

> How can we change it? The problem I am trying to solve, is getting
> meaningful device instance names instead of the anonymous defaults.
> This includes in the canonical path. I am completely open to proposals
> :)

The qdev ID is for users.  Corollary: there is none unless the user sets
one.

The qdev ID is fixed at creation time, and never changes.  If it could
change, we'd need machinery to notify clients such as libvirt, and we'd
still suffer race conditions in multiple monitor situations.

The need for a way to uniquely identify device instances by some name is
real.  But qdev IDs as presently designed are not a solution.

What about the canonical QOM path?

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