On Mon, Jun 25, 2012 at 03:51:13AM -0400, m...@linux.vnet.ibm.com wrote: > > Quoting Stefan Hajnoczi <stefa...@gmail.com>: > > >On Wed, Jun 20, 2012 at 7:47 AM, Cong Meng <m...@linux.vnet.ibm.com> wrote: > >>Implement the hotplug() and hot_unplug() interfaces in virtio-scsi, > >>by signal > >>the virtio_scsi.ko in guest kernel via event virtual queue. > >> > >>The counterpart patch of virtio_scsi.ko will be sent soon in another thread. > > > >>Signed-off-by: Cong Meng <m...@linux.vnet.ibm.com> > >>Signed-off-by: Sen Wang <senw...@linux.vnet.ibm.com> > >>--- > >> hw/virtio-scsi.c | 72 > >>+++++++++++++++++++++++++++++++++++++++++++++++++++-- > >> 1 files changed, 69 insertions(+), 3 deletions(-) > > > >I compared against the virtio-scsi specification and this looks good: > >http://ozlabs.org/~rusty/virtio-spec/virtio-0.9.5.pdf > > > >Dropped events and event throttling are not implemented by this patch. > > This means that the guest can miss events if it runs out of event > >queue elements. A scenario that might be able to trigger this is if > >multiple LUNs are hotplugged in a single QEMU monitor callback. > > > >Implementing dropped events is easy in hw/virtio-scsi.c. Keep a bool > >or counter of dropped events and report them when the guest kicks us > >with a free event element (virtio_scsi_handle_event). > > Yes. It's easy to do this in qemu. But I'm not sure what should be done > in virtio-scsi.ko to respond the "VIRTIO_SCSI_T_EVENTS_MISSED" event. > The spec says "poll the logical units for unit attention conditions", or > just a whole bus rescan?
I'm not sure what the answer is either, maybe you can find an existing SCSI LLD that does what you need. Stefan
