Re: [Qemu-devel] [PATCH V7 1/5] runstate: introduce prelaunch-migrate state

[Jason Wang <jasowang@redhat.com>]

On 03/11/2013 10:31 PM, Jiri Denemark wrote:
> On Thu, Mar 07, 2013 at 08:37:17 -0700, Eric Blake wrote:
>> On 03/07/2013 01:23 AM, Jason Wang wrote:
>>> Sometimes, we need track the state when guest is just about to start after
>>> migration. There's not a accurate state available which do this accurately
>>> (consider qemu may started with -S in destination).
>> s/may/may be/
>>
>> and yes, libvirt _always_ starts qemu with -S in the destination.
>>
>>> So this patch introduces a new state prelaunch-migrate which just tracks this
>>> state, it covers the case both w/ and w/o -S in destination. The first user of
>>> this is the support of doing announce by guest.
>>>
>>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>>> ---
>>>  migration.c      |    3 +--
>>>  qapi-schema.json |    5 ++++-
>>>  vl.c             |    4 +++-
>>>  3 files changed, 8 insertions(+), 4 deletions(-)
>> I'm not sure if this patch will have any negative effects on existing
>> libvirt migration or state reporting; adding Jirka to cc.
> I don't see any issues this patch could cause to libvirt. The only place
> where we ask qemu for its current state is when we reconnect to existing
> qemu processes after libvirtd restart. And the only thing we care about
> is whether the guest is running or not. We use our own state information
> to detect if we were migrating or not.
>
> Jirka
>

Thanks for the checking. Since Michael prefers a device specific method
instead of introducing a new runstate, I plan to use post load and vm
state change handler instead of this new runstate in next version.