Re: [PATCH 1/2] virtio-scsi: first version

[Paolo Bonzini <pbonzini@redhat.com>]

On 12/03/2011 12:07 AM, Benjamin Herrenschmidt wrote:
> This is typically the one thing you should -really- obtain from the
> other side. This is the number one reason why we cannot today reliably
> emulate a SCSI controller in qemu -and- pass-through the SCSI commands
> to the host /dev/sg or equivalent (only full device emulation is
> reliable).
>
> This is also typically what something like virtio-scsi allows us to fix,
> so let's fix it. IE. we have the ability to query the "limits" of the
> real HBA /  transport on the host side and to pass them along to the
> guest, which enables us to do real pass-through.

You can fix this in QEMU; READ and WRITE commands can be split in 
multiple parts.  The scsi-block device I added recently does this.

However, it seems like a simple change, so I'll do it.  I'll add 
max_sectors and cmd_per_lun to the config space.

Paolo