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

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

Oops, forgot to include Kevin and Stefan on cc for this.

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