Re: [Qemu-devel] [PATCH 2/2] atapi migration: Throw recoverable error to avoid recovery

[Kevin Wolf <kwolf@redhat.com>]

Am 16.01.2015 um 18:28 hat John Snow geschrieben:
> 
> 
> On 12/09/2014 01:15 PM, Dr. David Alan Gilbert (git) wrote:
> >From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> >
> >(With the previous atapi_dma flag recovery)
> >If migration happens between the ATAPI command being written and the
> >bmdma being started, the DMA is dropped.  Eventually the guest times
> >out and recovers, but that can take many seconds.
> >(This is rare, on a pingpong reading the CD continuously I hit
> >this about ~1/30-1/50 migrates)
> >
> >I don't think we've got enough state to be able to recover safely
> >at this point, so I throw a 'medium error, no seek complete'
> >that I'm assuming guests will try and recover from an apparently
> >dirty CD.
> >
> >OK, it's a hack, the real solution is probably to push a lot of
> >ATAPI state into the migration stream, but this is a fix that
> >works with no stream changes. Tested only on Linux (both RHEL5
> >(pre-libata) and RHEL7).
> >
> >Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> I think this workaround is sensible until we develop a more precise fix.
> 
> Reviewed-by: John Snow <jsnow@redhat.com>

Thanks, applied all to the block branch.

Kevin