Re: [Qemu-devel] [QEMU question] Disk hot plugging without working PCI hotplug - possible?

[Frederic Konrad <fred.konrad@greensocs.com>]

On 06/06/2013 15:59, Alexey Kardashevskiy wrote:
> On 06.06.2013 22:44, Frederic Konrad wrote:
>> On 06/06/2013 12:13, Alexey Kardashevskiy wrote:
>>> Hi!
>>>
>>> For the pseries platform (server PPC64) we do not support PCI hotplug
>>> yet.
>>> However we still want to hot plug disks.
>>>
>>> As a workaround, we could add multiple SCSI host devices
>>> (virtio-scsi-pci,
>>> spapr-vscsi) without any disk attached and later (using qemu console)
>>> attach drives to them as we do with the "-drive" parameter in the
>>> command line.
>>>
>>> So I enabled CONFIG_PCI_HOTPLUG_OLD=y and tried.
>>>
>>> However, drive_add console command works only with PCI what eliminates
>>> "spapr-vscsi" from the list. Oookay.
>>>
>>> Then I tried running qemu with "-device virtio-scsi-pci,id=device0" and
>>> later doing "drive_add 0 file=virtimg/test1" from the qemu console. This
>>> time qemu responded with "Device is not a SCSI adapter" what is
>>> correct as
>>> nowadays virtio-XXXX-pci devices are not what are they called as they
>>> simply create underlying virtio-bus, attach a real virtio-XXXX-device
>>> there
>>> (which is not PCI) and only then attach disk to non-PCI virtio device.
>> Hi,
>>
>> Seems it's a bug: il should be compatible with the old virtio-scsi-pci.
>> What's the meaning of the "0" in drive_add command?
> It is a PCI slot number, the complete address would include a domain and
> a bus.
>
>

Ok thanks, I'll take a look.
>> Fred
>>> So as I see there is no way to attach a disk to an existing controller in
>>> already running qemu.
>>>
>>> This is how I add disks to qemu now:
>>>    -device virtio-scsi-pci,id=virtioscsi0 \
>>>    -drive file=virtimg/fc18guest,if=none,id=drive0,readonly=off,
>>> format=raw,media=disk,werror=stop,rerror=stop \
>>>    -device scsi-disk,id=scsidisk0,bus=virtioscsi0.0,channel=0,
>>> scsi-id=0,lun=0,drive=drive0,removable=off \

This two last command isn't available in the monitor?
>>>
>>> I want to only add "-device virtio-scsi-pci,id=virtioscsi0" to the
>>> command
>>> line and do the rest from the qemu console.
>>>
>>> Am I missing some useful command from qemu console or anything else?
>>> Thanks!
>