On Fri, Sep 14, 2012 at 08:45:11AM +0200, Paolo Bonzini wrote:

Il 14/09/2012 00:27, Nicholas A. Bellinger ha scritto:

quoted

*) Keep vhost-scsi as a backend to virtio-scsi-pci

  - Reduces duplicated code amongst multiple virtio-scsi backends.
  
  - Follows the split for what existing vhost-net code already does.

So that said, two quick questions for Paolo & Co..

For the standalone vhost-scsi-pci device case, can you give a brief idea
as to what extent you'd like to see virtio-scsi.c code/defs duplicated
and/or shared amongst a new vhost-scsi-pci device..?

Not much, in the end, would be shared; it could end up being just
parts of virtio_scsi_init and virtio_scsi_exit, and virtio_scsi_get_config.

Almost all the other code is to implement the SCSI bus interface,
which you do not need.

I don't remember if and how vhost handles configuration changes.

All configuration changes are handled in userspace.

 If you
need any struct in virtio-scsi.c, either move it to virtio-scsi.h or
add the new device in the same file.

quoted

Also to help me along, can you give an example based on the current
usage below how the QEMU command line arguments would change with a
standalone vhost-scsi-pci device..?

./x86_64-softmmu/qemu-system-x86_64 -enable-kvm -smp 4 -m 2048 \
    -hda /usr/src/qemu-vhost.git/debian_squeeze_amd64_standard-old.qcow2 \
    -vhost-scsi id=vhost-scsi0,wwpn=naa.600140579ad21088,tpgt=1 \
    -device virtio-scsi-pci,vhost-scsi=vhost-scsi0,event_idx=off

Two possibilities.  Either simply do s/virtio-scsi-pci/vhost-scsi-pci/ or do

./x86_64-softmmu/qemu-system-x86_64 -enable-kvm -smp 4 -m 2048 \
    -hda /usr/src/qemu-vhost.git/debian_squeeze_amd64_standard-old.qcow2 \
    -device virtio-scsi-pci,wwpn=naa.600140579ad21088,tpgt=1,event_idx=off

I think I like the second option better.

-- 
MST