Re: [Qemu-devel] [PATCH 0/2] ATAPI migration fix/hack

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

* Dr. David Alan Gilbert (dgilbert@redhat.com) wrote:
> 
> Oops, forgot to include Kevin and Stefan on cc for this.

Ping;
John R-b'd the two patches:
  https://lists.gnu.org/archive/html/qemu-devel/2014-12/msg01133.html
  http://lists.gnu.org/archive/html/qemu-devel/2015-01/msg01956.html

although hmm, possibly before I added both of you on
the cc.

Dave

> 
> Dave
> 
> * Dr. David Alan Gilbert (git) (dgilbert@redhat.com) wrote:
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > 
> > This pair of patches fixes a problem where IDE/ATAPI cdrom
> > reads get lost/corrupted over migration.
> > 
> > The first of the patches (restore atapi_dma flag) is
> > a simple fix that I think is safe; it no longer causes
> > corruption in the case we saw, but does still trigger
> > a long timeout.
> > 
> > The second is a hack; it throws a medium error causing
> > the guest to retry the command in the case where migration
> > happens just between the IDE/ATAPI command being submitted
> > and the bmdma being finished.   This recovers a lot
> > faster than the timeout.
> > 
> > Only tried on Linux guests so far; I think it might be possible
> > to replace both of these by reparsing the command buffer for
> > ATAPI; I'm just not confident I know when that's safe to do,
> > and I wanted to see how disgusted people were by the 2nd hack.
> > 
> > Dave
> > 
> > Dr. David Alan Gilbert (2):
> >   Restore atapi_dma flag across migration
> >   atapi migration: Throw recoverable error to avoid recovery
> > 
> >  hw/ide/atapi.c    | 17 +++++++++++++++++
> >  hw/ide/core.c     |  1 +
> >  hw/ide/internal.h |  2 ++
> >  hw/ide/pci.c      | 11 +++++++++++
> >  4 files changed, 31 insertions(+)
> > 
> > -- 
> > 2.1.0
> > 
> > 
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK