Solaris DDI specific (Solaris DDI)

When auto request sense has been enabled using scsi_ifsetcap(9F) and the "auto-rqsense" capability, the target driver must allocate a status area in the SCSI packet structure for the auto request sense structure (see scsi_pkt(9S)). In the event of a check condition, the transport layer automatically executes a request sense command. This check ensures that the request sense information does not get lost. The auto request sense structure supplies the SCSI status of the original command, the transport information pertaining to the request sense command, and the request sense data.

struct scsi_status          sts_status;            /* SCSI status */
struct scsi_status          sts_rqpkt_status;      /* SCSI status of   
                                                      request sense cmd */
uchar_t                     sts_rqpkt_reason;      /* reason completion */
uchar_t                     sts_rqpkt_resid;       /* residue */
uint_t                      sts_rqpkt_state;       /* state of command */
uint_t                      sts_rqpkt_statistics;  /* statistics */
struct scsi_extended_sense  sts_sensedata;         /* actual sense data */

sts_status is the SCSI status of the original command. If the status indicates a check condition, the transport layer might have performed an auto request sense command.

sts_rqpkt_status is the SCSI status of the request sense command. sts_rqpkt_reason is the completion reason of the request sense command. If the reason is not CMD_CMPLT, then the request sense command did not complete normally.

sts_rqpkt_resid is the residual count of the data transfer and indicates the number of data bytes that have not been transferred. The auto request sense command requests SENSE_LENGTH bytes.

sts_rqpkt_state has bit positions representing the five most important statuses that a SCSI command can go obtain.

sts_rqpkt_statistics maintains transport-related statistics of the request sense command.

sts_sensedata contains the actual sense data if the request sense command completed normally.

scsi_ifgetcap(9F), scsi_init_pkt(9F), scsi_extended_sense(9S), scsi_pkt(9S)

Writing Device Drivers