Il 23/08/2012 12:08, Stefan Hajnoczi ha scritto: >> I'm still trying to understand the extent of the problem. >> >> The problem occurs for _USB_ CD-ROMs according to Ben. Passthrough of >> USB storage devices should be done via USB passthrough, not virtio-scsi. >> If we do USB passthrough via the SCSI layer we miss on all the quirks >> that the OS may do based on the USB product/vendor pairs. There's no >> end to these, and some of the quirks may cause the device to lock up or >> corruption. >> >> I'd rather see a reproducer using SAS/ATA/ATAPI disks before punting. > > This issue affects passthrough: either an entire sg device or at least > a SG_IO ioctl (e.g. a non-READ/WRITE SCSI command). > > To reproduce it, check host queue limits and guest virtio-scsi queue > limits. Then pick a command that can exceed the limits and try it > from inside the guest :).
Yes, so much is clear. But does it happen _in practice_? Do initiators actually issue commands that are that big? Paolo
