Re: [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi host device

[Paolo Bonzini <pbonzini@redhat.com>]

On 07/06/2017 17:39, Felipe Franciosi wrote:
> 
>> On 7 Jun 2017, at 16:37, Peter Maydell <peter.maydell@linaro.org> wrote:
>>
>> On 7 June 2017 at 16:28, Paolo Bonzini <pbonzini@redhat.com> wrote:
>>> From: Felipe Franciosi <felipe@nutanix.com>
>>>
>>> This commit introduces a vhost-user device for SCSI. This is based
>>> on the existing vhost-scsi implementation, but done over vhost-user
>>> instead. It also uses a chardev to connect to the backend. Unlike
>>> vhost-scsi (today), VMs using vhost-user-scsi can be live migrated.
>>>
>>> To use it, start Qemu with a command line equivalent to:
>>>
>>> qemu-system-x86_64 \
>>>       -chardev socket,id=vus0,path=/tmp/vus.sock \
>>>       -device vhost-user-scsi-pci,chardev=vus0,bus=pci.0,addr=...
>>>
>>> A separate commit presents a sample application linked with libiscsi to
>>> provide a backend for vhost-user-scsi.
>>>
>>> Signed-off-by: Felipe Franciosi <felipe@nutanix.com>
>>> Message-Id: <1488479153-21203-4-git-send-email-felipe@nutanix.com>
>>> [Disable migration for now, since it does not support bdrv_drain. - Paolo]
>>
>> I was expecting this to mean a VMStateDescription with a
>> ".unmigratable = 1" field, but it doesn't seem to have one.
>> Does it disable migration some other way?
>
> Hi Peter,
> 
> vhost-user-scsi supports migration.

How, since there is no synchronization point between the vhost-user
server on the source and the destination?

Can you please send a version of your patch that uses .unmigratable?

I'll send a v6 that momentarily drops vhost-scsi, but I intend to
include it again in the next pull request.

Thanks,

Paolo