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. I suggested to deprecate it in review of "[PATCH v3 14/15] qapi: introduce DEVICE_ON event" (Message-ID: <873579x67l.fsf@pond.sub.org>). Quote: We commonly send both device ID and QOM path, mostly for historical reasons: the former precede the latter. There are exceptions, such as query-cpus-fast. Can't say offhand whether CPUs can be created with IDs. [...] I'd be in favour of deprecating and deleting redundant device IDs in QMP output.