Il 22/08/2012 13:04, Cong Meng ha scritto:

quoted

Cong, what is the limit that the host HBA enforces (and what is the
HBA)?  What commands see a problem?  Is it fixed by using scsi-block
instead of scsi-generic (if you can use scsi-block at all, i.e. it's not
a tape or similar device)?

I don't see real problem caused by the the queue limits actually. It's a
bug which Stefan told me.

I'd rather avoid patching the specification if not to solve real (rather
than known-but-theoretical) problems.

quoted

With scsi-generic, QEMU uses a bounce buffer for non-I/O commands to a
SCSI passthrough device, so the only problem in that case should be the
maximum segment size.  This could change in the future, but max_segments
and max_sectors should not yet be a problem.

about bounce buffer, do you meat the buffer allocated in
scsi_send_command() of hw/scsi-generic.c?

Yes.

Paolo