Re: [Qemu-devel] [Question] How can we confirm hot-plug disk succesfully?

[Xie Changlong]

在 6/19/2017 3:27 PM, Kevin Wolf 写道:
> Am 18.06.2017 um 09:21 hat Xie Changlong geschrieben:
> > In device hot-remove scenario, if we don't probe acpiphp module on
> > the guest, 'device_del' will never emit DEVICE_DELETED event(because
> > guest will not write to __EJ0) . So we can confirm that hot-remove
> > failed. But IIUC, there is no event such as DEVICE_ADDED, so
> > 1) How can we confirm hotplug('device_add') successfully?
> > 2) It seems when hot-plug disk, we don't care acpiphp module status
> > on the guest, am I right?
> > 3) Why there is no DEVICE_ADDED like event?
>
> device_add doesn't need guest cooperation, so it is immediately
> completed when the QMP command returns success.

That's what i though too. But I have a question, if we don't proble 
acpiphp on the guest, and execute below commands:

Hot plug:
(qemu) drive_add 0 
file=/resource/changlox/test.raw,id=drive-virtio-disk1,if=none
(qemu) device_add virtio-blk-pci,drive=drive-virtio-disk1,id=virtio-disk1

Hot remove:
(qemu) device_del virtio-disk1
(qemu) drive_del drive-virtio-disk1
(qemu) qom-list /machine/peripheral
type (string)
virtio-disk1 (child<virtio-blk-pci>)
(qemu) info block
foo (#block122): suse1.qcow2 (qcow2)
    Cache mode:       writeback, direct
    Backing file:     suse.qcow2.orgin (chain depth: 1)

ide1-cd0: [not inserted]
    Removable device: not locked, tray closed

floppy0: [not inserted]
    Removable device: not locked, tray closed

sd0: [not inserted]
    Removable device: not locked, tray closed
(qemu) drive_add 0 
file=/resource/changlox/test.raw,id=drive-virtio-disk1,if=none
Duplicate ID 'drive-virtio-disk1' for drive

'info block' shows nothing, but we can't add drive who's id 
is'drive-virtio-disk1' too。 There is a more serious situation, we could 
*never* destory device memory with 'device_del', it's memory leak to me 
if the guest os never support hot-plug and the user don't know this 
information.



> Kevin

--
Thanks
    -Xie