On Thu, 28 Nov 2019 at 17:27, Igor Mammedov <imamm...@redhat.com> wrote: > > On Thu, 28 Nov 2019 16:00:06 +0000 > Peter Maydell <peter.mayd...@linaro.org> wrote: > > Once a device is hot-unplugged (and thus unrealized) is it valid > > for it to be re-hot-plugged, or is the assumption that it's then > > destroyed and a fresh device is created if the user wants to plug > > something in again later ? Put another way, is it valid for a qdev > > device to see state transitions realize -> unrealize -> realize ? > > I don't think we do it currently (or maybe we do with failover but > I missed that train), but I don't see why it can't be done.
Well, as Eduardo says, if we don't currently do it then we probably have a lot of subtly buggy code. Requiring it to work imposes a requirement on the 'unrealize' function that it doesn't just do required cleanup/resource releasing actions, but also returns the device back to exactly the state it was in after instance_init, so that 'realize' will work correctly. That's quite a lot of code auditing/effort if we don't actually have a current or future use for making this work, rather than just requiring that an unrealized device object is immediately finalized without possibility of resurrection. If we do have a plausible usecase then I think we should document that unrealize needs to handle this, and also have a basic smoke test of the realize->unrealize->realize. thanks -- PMM
