Hi.
Suppose I want to set a property of a non-pluggable device that cannot be set after the device has been realized (e.g., I can't use qmp to set the property after QEMU has started).
Being non-pluggable means I can't use "-device foo,bar=baz" on the command line.
[But I can use "-device foo,help" to list its properties :-) (if I also specify -M bar) ]
How do people do this?
The device is part of a "machine" (board really), so I could add the property to the machine to be passed on to the device when it's realized (at least I think I can), but that doesn't feel right: The machine has lots of devices -> it feels cleaner to associate the property with the device and not the machine (lest the machine over time collect a myriad of random properties to pass on to its devices). Things get a little complicated because the machine can have multiple copies of a device: specifying the device's name is insufficient.
The device has an object path: /machine/foo/bar/device[0]. There's also /.../device[1].
IWBN to be able to do something along the lines of:
-device-property /device/path[,PROP1=VALUE1,...]
copying the syntax used for "-object".
It's perhaps even nicer if this could be accomplished with -device: avoiding further confusion on what -device can and can't be used for (e.g., can I use -device-property to set a property that could also be set with -device?).
If what I'm asking for is reasonable and isn't doable today (I'm certainly willing to believe I'm missing something), I'm happy to work on the patch (with some guidance as to what would be acceptable).
One thought that comes to mind is to use -object, store the properties there, and have the machine collect them from there when realizing its devices. Or is that an abuse of -object ?