scsi-disk: fix the check of the DBD bit in the MODE SENSE command

The DBD bit does not work as expected.

SCSI-Spec:
http://ldkelley.com/SCSI2/SCSI2/SCSI2-08.html#8.2.10
"A disable block descriptors (DBD) bit of zero indicates that the target
may return zero or more block descriptors in the returned MODE SENSE
data (see 8.3.3), at the target's discretion. A DBD bit of one
specifies that the target shall not return any block descriptors in the
returned MODE SENSE data."

Signed-off-by: Bernhard Kohl <bernhard.kohl@nsn.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
index 44f99b0..0c90c77 100644 (file)
--- a/hw/scsi-disk.c
+++ b/hw/scsi-disk.c
@@ -655,7 +655,7 @@ static int scsi_disk_emulate_mode_sense(SCSIRequest *req, uint8_t *outbuf)
     }
 
     bdrv_get_geometry(s->bs, &nb_sectors);
-    if ((~dbd) & nb_sectors) {
+    if (!dbd && nb_sectors) {
         if (req->cmd.buf[0] == MODE_SENSE) {
             outbuf[3] = 8; /* Block descriptor length  */
         } else { /* MODE_SENSE_10 */