Re: [PATCH] audio: Never send migration section

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Philippe Mathieu-Daudé (philmd@redhat.com) wrote:
> On 8/9/21 7:12 PM, Daniel P. Berrangé wrote:
> > On Mon, Aug 09, 2021 at 06:09:56PM +0100, Dr. David Alan Gilbert (git) wrote:
> >> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> >>
> >> The audio migration vmstate is empty, and always has been; we can't
> >> just remove it though because an old qemu might send it us.
> >> Changes with -audiodev now mean it's sometimes created when it didn't
> >> used to be, and can confuse migration to old qemu.
> 
> Not a 6.1 regression but easy change for rc3 IMO.
> 
> >> Change it so that vmstate_audio is never sent; if it's received it
> >> should still be accepted, and old qemu's shouldn't be too upset if it's
> >> missing.
> 
> Worth Cc: stable@ maybe?

Hmm yes, cc'd this reply.

Dave

> >> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> >> ---
> >>  audio/audio.c | 10 ++++++++++
> >>  1 file changed, 10 insertions(+)
> > 
> > Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
> > Tested-by: Daniel P. Berrangé <berrange@redhat.com>
> > 
> > 
> > For testing I have a VM with -audiodev, but *WITHOUT* any sound
> > frontend devices. Live migrating to a QEMU using QEMU_AUDIO_DRV
> > would previously fail. With this applied it now works, showing
> > that we dont uncessarily send this.
> > 
> > I also tested migration to a QEMU with -audiodev, but without
> > this patch, and that still works as before, showing that QEMU
> > is happy if this section is not sent.
> > 
> >>
> >> diff --git a/audio/audio.c b/audio/audio.c
> >> index 59453ef856..54a153c0ef 100644
> >> --- a/audio/audio.c
> >> +++ b/audio/audio.c
> >> @@ -1622,10 +1622,20 @@ void audio_cleanup(void)
> >>      }
> >>  }
> >>  
> >> +static bool vmstate_audio_needed(void *opaque)
> >> +{
> >> +    /*
> >> +     * Never needed, this vmstate only exists in case
> >> +     * an old qemu sends it to us.
> >> +     */
> >> +    return false;
> >> +}
> >> +
> >>  static const VMStateDescription vmstate_audio = {
> >>      .name = "audio",
> >>      .version_id = 1,
> >>      .minimum_version_id = 1,
> >> +    .needed = vmstate_audio_needed,
> >>      .fields = (VMStateField[]) {
> >>          VMSTATE_END_OF_LIST()
> >>      }
> >> -- 
> >> 2.31.1
> >>
> > 
> > Regards,
> > Daniel
> > 
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK