nscsi: make sun4 probe-scsi happy (nw)

src/devices/machine/nscsi_bus.cpp

@@ -563,11 +563,13 @@ void nscsi_full_device::scsi_data_out(int buf, int size)
 	c->param2 = size;
 }
 
-void nscsi_full_device::sense(bool deferred, uint8_t key)
+void nscsi_full_device::sense(bool deferred, uint8_t key, uint8_t asc, uint8_t ascq)
 {
 	memset(scsi_sense_buffer, 0, sizeof(scsi_sense_buffer));
 	scsi_sense_buffer[0] = deferred ? 0x71 : 0x70;
 	scsi_sense_buffer[2] = key;
+	scsi_sense_buffer[12] = asc;
+	scsi_sense_buffer[13] = ascq;
 }
 
 void nscsi_full_device::scsi_unknown_command()
@@ -586,7 +588,11 @@ void nscsi_full_device::scsi_command()
 	switch(scsi_cmdbuf[0]) {
 	case SC_REQUEST_SENSE:
 		LOG("command REQUEST SENSE\n");
-		scsi_data_in(SBUF_SENSE, 8);
+		/*
+		 * Targets shall be capable of returning eighteen bytes of data in
+		 * response to a REQUEST SENSE command.
+		 */
+		scsi_data_in(SBUF_SENSE, 18);
 		scsi_status_complete(SS_GOOD);
 		break;
 	default:
@@ -619,7 +625,9 @@ int nscsi_full_device::get_lun(int def)
 void nscsi_full_device::bad_lun()
 {
 	scsi_status_complete(SS_CHECK_CONDITION);
-	sense(false, 2);
+
+	// key:illegal request, asc:logical unit not supported
+	sense(false, 5, 0x25);
 }
 
 // Arbitration delay (2.4us)

src/devices/machine/nscsi_bus.h

@@ -285,7 +285,7 @@ protected:
 	void scsi_data_in(int buf, int size);
 	void scsi_data_out(int buf, int size);
 
-	void sense(bool deferred, uint8_t key);
+	void sense(bool deferred, uint8_t key, uint8_t asc = 0, uint8_t ascq = 0);
 	int get_lun(int def = 0);
 	void bad_lun();
 
@@ -354,7 +354,7 @@ protected:
 	// Fast negation period (30ns)
 	virtual attotime scsi_fast_negation_period();
 
-	uint8_t scsi_cmdbuf[4096], scsi_sense_buffer[8];
+	uint8_t scsi_cmdbuf[4096], scsi_sense_buffer[18];
 	int scsi_cmdsize;
 	uint8_t scsi_identify;
 

src/devices/machine/nscsi_cd.cpp

@@ -113,6 +113,22 @@ void nscsi_cdrom_device::scsi_command()
 		int lun = get_lun(scsi_cmdbuf[1] >> 5);
 		LOG("command INQUIRY lun=%d EVPD=%d page=%d alloc=%02x link=%02x\n",
 					lun, scsi_cmdbuf[1] & 1, scsi_cmdbuf[2], scsi_cmdbuf[4], scsi_cmdbuf[5]);
+
+		/*
+		 * 7.5.3 Selection of an invalid logical unit
+		 *
+		 * The logical unit may not be valid because:
+		 * a) the target does not support the logical unit (e.g. some targets
+		 *    support only one peripheral device). In response to an INQUIRY
+		 *    command, the target shall return the INQUIRY data with the
+		 *    peripheral qualifier set to the value required in 8.2.5.1.
+		 *
+		 * If the logic from the specification above is applied, Sun SCSI probe
+		 * code gets confused and reports multiple valid logical units are 
+		 * attached; proper behaviour is produced when check condition status
+		 * is returned with sense data ILLEGAL REQUEST and LOGICAL UNIT NOT
+		 * SUPPORTED.
+		 */
 		if(lun) {
 			bad_lun();
 			return;
@@ -224,7 +240,7 @@ void nscsi_cdrom_device::scsi_command()
 		int pmin = page == 0x3f ? 0x00 : page;
 		for(int page=pmax; page >= pmin; page--) {
 			switch(page) {
-			case 0x00: // Unit attention parameters page (weird)
+			case 0x00: // Vendor specific (does not require page format)
 				scsi_cmdbuf[pos++] = 0x80; // PS, page id
 				scsi_cmdbuf[pos++] = 0x02; // Page length
 				scsi_cmdbuf[pos++] = 0x00; // Meh