Re: [PATCH v4 14/16] qapi: deprecate "device" field of DEVICE_* events

[Peter Krempa]

On Tue, Feb 14, 2023 at 09:54:22 +0100, Markus Armbruster wrote:
> Daniel P. Berrangé <berrange@redhat.com> writes:
> 
> > On Mon, Feb 13, 2023 at 05:01:01PM +0300, Vladimir Sementsov-Ogievskiy 
> > wrote:
> >> The device field is redundant, because QOM path always include device
> >> ID when this ID exist.
> >
> > The flipside to that view is that applications configuring QEMU are
> > specifying the device ID for -device (CLI) / device_add (QMP) and
> > not the QOM path. IOW, the device ID is the more interesting field
> > than QOM path, so feels like the wrong one to be dropping.
> 
> QOM path is a reliable way to identify a device.  Device ID isn't:
> devices need not have one.  Therefore, dropping the QOM path would be
> wrong.
> 
> > Is there any real benefit to dropping this ? 
> 
> The device ID is a trap for the unwary: relying on it is fine until you
> run into a scenario where you have to deal with devices lacking IDs.

Note that libvirt's code is still using the 'device' bit rather than QOM
path and the fix might not be entirely trivial although should not be
too hard.