Re: [Qemu-devel] Re: [PATCH] virtio-blk: add SGI_IO passthru support

[Christian Borntraeger]

Am Wednesday 29 April 2009 12:50:04 schrieb Christoph Hellwig:
> On Tue, Apr 28, 2009 at 09:09:52PM +0200, Christian Borntraeger wrote:
> > Yes, virtio-scsi is also something we were thinking of. The last time we 
> > discussed this idea of SCSI passthrough internally, we stumbled over error 
> > recovery. Who is responsible for the error recovery? The host, the guest, 
> > or both? Are there problems, which will trigger error recovery in the guest 
> > and host midlayer at the same time? To be honest, my scsi knowledge is very 
> > limited, so I dont know if that is a real problem.
> 
> I'm not that far with planning yet.  The best way would be to do real
> error handling in the host probably.

Yes, that was my impression too. The tricky part is the timeout based recovery 
found in the scsi midlayer (e.g. scsi-error.c). In case of a timeout the guest 
and the host will start recovery at the same time.

Christian