Index: sbin/camcontrol/camcontrol.8
===================================================================
--- sbin/camcontrol/camcontrol.8	(revision 291390)
+++ sbin/camcontrol/camcontrol.8	(working copy)
@@ -104,6 +104,9 @@
 .Ic reset
 .Aq all | bus Ns Op :target:lun
 .Nm
+.Ic reprobe
+.Aq bus:target:lun
+.Nm
 .Ic defects
 .Op device id
 .Op generic args
@@ -548,6 +551,9 @@
 connecting to that device.
 Note that this can have a destructive impact
 on the system.
+.It Ic reprobe
+Tell the kernel to re-probe the given bus:target:lun
+(XPT_REPROBE_DEV) by issuing an async event to peripheral device.
 .It Ic defects
 Send the
 .Tn SCSI
Index: sbin/camcontrol/camcontrol.c
===================================================================
--- sbin/camcontrol/camcontrol.c	(revision 291390)
+++ sbin/camcontrol/camcontrol.c	(working copy)
@@ -100,7 +100,8 @@
 	CAM_CMD_APM		= 0x00000021,
 	CAM_CMD_AAM		= 0x00000022,
 	CAM_CMD_ATTRIB		= 0x00000023,
-	CAM_CMD_OPCODES		= 0x00000024
+	CAM_CMD_OPCODES		= 0x00000024,
+	CAM_CMD_REPROBE		= 0x00000025
 } cam_cmdmask;
 
 typedef enum {
@@ -193,6 +194,7 @@
 #endif /* MINIMALISTIC */
 	{"rescan", CAM_CMD_RESCAN, CAM_ARG_NONE, NULL},
 	{"reset", CAM_CMD_RESET, CAM_ARG_NONE, NULL},
+	{"reprobe", CAM_CMD_REPROBE, CAM_ARG_NONE, NULL},
 #ifndef MINIMALISTIC
 	{"cmd", CAM_CMD_SCSI_CMD, CAM_ARG_NONE, scsicmd_opts},
 	{"command", CAM_CMD_SCSI_CMD, CAM_ARG_NONE, scsicmd_opts},
@@ -273,6 +275,7 @@
 static int rescan_or_reset_bus(path_id_t bus, int rescan);
 static int scanlun_or_reset_dev(path_id_t bus, target_id_t target,
     lun_id_t lun, int scan);
+static int reprobe_dev(path_id_t bus, target_id_t target, lun_id_t lun);
 #ifndef MINIMALISTIC
 static int readdefects(struct cam_device *device, int argc, char **argv,
 		       char *combinedopt, int retry_count, int timeout);
@@ -3127,6 +3130,34 @@
 }
 
 static int
+doreprobe(int argc, char **argv)
+{
+	static const char must[] =
+		"you must specify a bus:target:lun to reprobe";
+	int rv;
+	path_id_t bus = CAM_BUS_WILDCARD;
+	target_id_t target = CAM_TARGET_WILDCARD;
+	lun_id_t lun = CAM_LUN_WILDCARD;
+	char *tstr;
+
+	if (argc < 3) {
+		warnx(must);
+		return(1);
+	}
+
+	tstr = argv[optind];
+	while (isspace(*tstr) && (*tstr != '\0'))
+		tstr++;
+	rv = parse_btl(argv[optind], &bus, &target, &lun, &arglist);
+	if (rv != 3) {
+		warnx(must);
+		return(1);
+	}
+
+	return(reprobe_dev(bus, target, lun));
+}
+
+static int
 rescan_or_reset_bus(path_id_t bus, int rescan)
 {
 	union ccb ccb, matchccb;
@@ -3382,6 +3413,59 @@
 	}
 }
 
+static int
+reprobe_dev(path_id_t bus, target_id_t target, lun_id_t lun)
+{
+	union ccb ccb;
+	struct cam_device *device;
+	int fd;
+
+	device = NULL;
+
+	if (bus == CAM_BUS_WILDCARD) {
+		warnx("invalid bus number %d", bus);
+		return(1);
+	}
+
+	if (target == CAM_TARGET_WILDCARD) {
+		warnx("invalid target number %d", target);
+		return(1);
+	}
+
+	if (lun == CAM_LUN_WILDCARD) {
+		warnx("invalid lun number %jx", (uintmax_t)lun);
+		return(1);
+	}
+
+	fd = -1;
+
+	bzero(&ccb, sizeof(union ccb));
+
+	if ((fd = open(XPT_DEVICE, O_RDWR)) < 0) {
+		warnx("error opening transport layer device %s\n",
+		    XPT_DEVICE);
+		warn("%s", XPT_DEVICE);
+		return(1);
+	}
+
+	ccb.ccb_h.func_code = XPT_REPROBE_DEV;
+	ccb.ccb_h.path_id = bus;
+	ccb.ccb_h.target_id = target;
+	ccb.ccb_h.target_lun = lun;
+
+	if (ioctl(fd, CAMIOCOMMAND, &ccb) < 0) {
+		warn("CAMIOCOMMAND ioctl failed");
+		close(fd);
+		return(1);
+	}
+	close(fd);
+
+	fprintf(stdout, "Re-probe of %d:%d:%jx was successful\n",
+	    bus, target, (uintmax_t)lun);
+
+	return(0);
+}
+
 #ifndef MINIMALISTIC
 
 static struct scsi_nv defect_list_type_map[] = {
@@ -8685,6 +8769,7 @@
 #endif /* MINIMALISTIC */
 "        camcontrol rescan     <all | bus[:target:lun]>\n"
 "        camcontrol reset      <all | bus[:target:lun]>\n"
+"        camcontrol reprobe    bus:target:lun\n"
 #ifndef MINIMALISTIC
 "        camcontrol defects    [dev_id][generic args] <-f format> [-P][-G]\n"
 "                              [-q][-s][-S offset][-X]\n"
@@ -9053,6 +9138,7 @@
 	 */
 	if ((cmdlist == CAM_CMD_RESCAN)
 	 || (cmdlist == CAM_CMD_RESET)
+	 || (cmdlist == CAM_CMD_REPROBE)
 	 || (cmdlist == CAM_CMD_DEVTREE)
 	 || (cmdlist == CAM_CMD_USAGE)
 	 || (cmdlist == CAM_CMD_DEBUG))
@@ -9204,6 +9290,9 @@
 		case CAM_CMD_RESET:
 			error = dorescan_or_reset(argc, argv, 0);
 			break;
+		case CAM_CMD_REPROBE:
+			error = doreprobe(argc, argv);
+			break;
 #ifndef MINIMALISTIC
 		case CAM_CMD_READ_DEFECTS:
 			error = readdefects(cam_dev, argc, argv, combinedopt,
Index: sys/amd64/conf/GENERIC
===================================================================
--- sys/amd64/conf/GENERIC	(revision 291390)
+++ sys/amd64/conf/GENERIC	(working copy)
@@ -366,3 +366,6 @@
 
 # The crypto framework is required by IPSEC
 device		crypto			# Required by IPSEC
+
+# Cam Debug Support
+options		CAMDEBUG
Index: sys/cam/cam_ccb.h
===================================================================
--- sys/cam/cam_ccb.h	(revision 291390)
+++ sys/cam/cam_ccb.h	(working copy)
@@ -193,6 +193,11 @@
 				 * Set SIM specific knob values.
 				 */
 
+	XPT_REPROBE_DEV		= 0x1a,
+				/*
+				 * Re-probe the sepcified SCSI device.
+				 */
+
 	XPT_SMP_IO		= 0x1b | XPT_FC_DEV_QUEUED,
 				/* Serial Management Protocol */
 
@@ -767,6 +772,7 @@
  * Definitions for the asynchronous callback CCB fields.
  */
 typedef enum {
+	AC_UNIT_REPROBE		= 0x8000,/* Device reprobe user request */
 	AC_UNIT_ATTENTION	= 0x4000,/* Device reported UNIT ATTENTION */
 	AC_ADVINFO_CHANGED	= 0x2000,/* Advance info might have changes */
 	AC_CONTRACT		= 0x1000,/* A contractual callback */
Index: sys/cam/cam_xpt.c
===================================================================
--- sys/cam/cam_xpt.c	(revision 291390)
+++ sys/cam/cam_xpt.c	(working copy)
@@ -433,6 +433,13 @@
 				return (EINVAL);
 			}
 			break;
+		case XPT_REPROBE_DEV:
+			if (inccb->ccb_h.target_id == CAM_TARGET_WILDCARD ||
+			    inccb->ccb_h.target_lun == CAM_LUN_WILDCARD) {
+				xpt_release_bus(bus);
+				return (EINVAL);
+			}
+			break;
 		default:
 			break;
 		}
@@ -472,6 +479,29 @@
 			xpt_free_ccb(ccb);
 			break;
 
+		case XPT_REPROBE_DEV: {
+			struct cam_path path;
+
+			/*
+			 * Compile a path using the bus, target, and lun the
+			 * user passed in.
+			 */
+			if (xpt_compile_path(&path, NULL,
+					    inccb->ccb_h.path_id,
+				            inccb->ccb_h.target_id,
+					    inccb->ccb_h.target_lun) !=
+					    CAM_REQ_CMP){
+				error = EINVAL;
+				break;
+			}
+
+			/*
+			 * Notify interested parties
+			 */
+			xpt_async(AC_UNIT_REPROBE, &path, NULL);
+			break;
+
+		}
 		case XPT_DEBUG: {
 			union ccb ccb;
 
@@ -717,7 +747,7 @@
 		}
 		xpt_unlock_buses();
 		break;
-		}
+	}
 	default:
 		error = ENOTTY;
 		break;
Index: sys/cam/scsi/scsi_da.c
===================================================================
--- sys/cam/scsi/scsi_da.c	(revision 291390)
+++ sys/cam/scsi/scsi_da.c	(working copy)
@@ -1702,6 +1702,17 @@
 		}
 		break;
 	}
+	case AC_UNIT_REPROBE:
+	{
+		softc = (struct da_softc *)periph->softc;
+
+		xpt_print(periph->path,
+		    "Re-probe requested\n");
+		softc->flags &= ~DA_FLAG_PROBED;
+		dareprobe(periph);
+
+		break;
+	}
 	case AC_UNIT_ATTENTION:
 	{
 		union ccb *ccb;
@@ -2240,7 +2251,7 @@
 	 * would be to not attach the device on failure.
 	 */
 	xpt_register_async(AC_SENT_BDR | AC_BUS_RESET | AC_LOST_DEVICE |
-	    AC_ADVINFO_CHANGED | AC_SCSI_AEN | AC_UNIT_ATTENTION,
+	    AC_ADVINFO_CHANGED | AC_SCSI_AEN | AC_UNIT_ATTENTION | AC_UNIT_REPROBE,
 	    daasync, periph, periph->path);
 
 	/*
@@ -3244,12 +3255,11 @@
 					if (have_sense)
 						scsi_sense_print(
 							&done_ccb->csio);
-					else {
+					else
 						xpt_print(periph->path,
 						    "got CAM status %#x\n",
 						    done_ccb->ccb_h.status);
-					}
-
+					
 					xpt_print(periph->path, "fatal error, "
 					    "failed to attach to device\n");