> On Jan 26, 2022, at 4:35 AM, Stefan Hajnoczi <stefa...@redhat.com> wrote: > > On Tue, Jan 25, 2022 at 06:12:48PM +0000, Jag Raman wrote: >> >> >>> On Jan 25, 2022, at 5:32 AM, Stefan Hajnoczi <stefa...@redhat.com> wrote: >>> >>> On Wed, Jan 19, 2022 at 04:41:55PM -0500, Jagannathan Raman wrote: >>>> Allow hotplugging of PCI(e) devices to remote machine >>>> >>>> Signed-off-by: Elena Ufimtseva <elena.ufimts...@oracle.com> >>>> Signed-off-by: John G Johnson <john.g.john...@oracle.com> >>>> Signed-off-by: Jagannathan Raman <jag.ra...@oracle.com> >>>> --- >>>> hw/remote/machine.c | 29 +++++++++++++++++++++++++++++ >>>> 1 file changed, 29 insertions(+) >>> >>> Why is this code necessary? I expected the default hotplug behavior to >> >> I just discovered that TYPE_REMOTE_MACHINE wasn't setting up a hotplug >> handler for the root PCI bus. >> >> Looks like, some of the machines don’t support hotplugging PCI devices. I see >> that the ‘pc’ machine does support hotplug, whereas ‘q35’ does not. > > Hotplug is definitely possible with q35. I'm not familiar with the > hotplug code though so I don't know how exactly that works for q35.
I was referring to the root PCI bus, other buses in Q35 probably support hotplug. Please see error message below: QEMU 6.2.50 monitor - type 'help' for more information (qemu) device_add lsi53c895a,id=lsi2 Error: Bus 'pcie.0' does not support hotplugging -- Jag > >> We didn’t check hotplug in multiprocess-qemu previously because it was >> limited >> to one device per process, and the use cases attached the devices via >> command line. >> >>> pretty much handle this case - hotplugging device types that the bus >>> doesn't support should fail and unplug should already unparent/unrealize >>> the device. >> >> OK, that makes sense. We don’t need to test the device type during >> plug and unplug. >> >> Therefore, I don’t think we need a callback for the plug operation. We >> could set HotplugHandlerClass->unplug callback to the default >> qdev_simple_device_unplug_cb() callback. > > Great! > > Stefan
