Re: [PATCH V4 10/14] migration: stop vm for cpr

[Steven Sistare]

On 2/25/2024 9:08 PM, Peter Xu wrote:
> On Thu, Feb 22, 2024 at 09:28:36AM -0800, Steve Sistare wrote:
>> When migration for cpr is initiated, stop the vm and set state
>> RUN_STATE_FINISH_MIGRATE before ram is saved.  This eliminates the
>> possibility of ram and device state being out of sync, and guarantees
>> that a guest in the suspended state remains suspended, because qmp_cont
>> rejects a cont command in the RUN_STATE_FINISH_MIGRATE state.
>>
>> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> 
> Reviewed-by: Peter Xu <peterx@redhat.com>
> 
> cpr-reboot mode keeps changing behavior.
> 
> Could we declare it "experimental" until it's solid?  Maybe a patch to
> document this?
> 
> Normally IMHO we shouldn't merge a feature if it's not complete, however
> cpr-reboot is so special that the mode itself is already merged in 8.2
> before I started to merge patches, and it keeps changing things.  I don't
> know what else we can do here besides declaring it experimental and not
> declare it a stable feature.

Hi Peter, the planned/committed functionality for cpr-reboot changed only once, 
in:
    migration: stop vm for cpr

Suspension to support vfio is an enhancement which adds to the basic 
functionality,
it does not change it.  This was planned all along, but submitted as a separate 
series to manage complexity, as I outlined in my qemu community presentation,
which I emailed you at the time.

Other "changes" that arose during review were just clarifications and 
explanations.

So, I don't think cpr-reboot deserves to be condemned to experimental limbo.

- Steve