Index: lib/libcam/camlib.c
===================================================================
--- lib/libcam/camlib.c	(revision 291390)
+++ lib/libcam/camlib.c	(working copy)
@@ -752,3 +752,41 @@
 	bcopy(src, dst, sizeof(struct cam_device));
 
 }
+
+/*
+ * Send a reprobe unit request for a given bus, target and lun
+ */
+int
+cam_reprobe_btl(path_id_t path_id, target_id_t target_id, lun_id_t target_lun)
+{
+	int fd;
+	char *func_name = "cam_reprobe_btl";
+	union ccb ccb;
+
+	if ((fd = open(XPT_DEVICE, O_RDWR)) < 0) {
+		snprintf(cam_errbuf, CAM_ERRBUF_SIZE,
+			 "%s: couldn't open %s\n%s: %s", func_name, XPT_DEVICE,
+			 func_name, strerror(errno));
+		return(-1);
+	}
+
+	/* Setup our request ccb */
+	bzero(&ccb.ccb_h, sizeof(struct ccb_hdr));
+	ccb.ccb_h.path_id = path_id;
+	ccb.ccb_h.target_id = target_id;
+	ccb.ccb_h.target_lun = target_lun;
+
+	/*
+	 * Attempt to issue a unit reprobe request.  This ioctl will fail if the
+	 * kernel can't find a unit for the given path, target and lun.
+	 */
+	if (ioctl(fd, CAMUNITREPROBE, &ccb) != 0) {
+		snprintf(cam_errbuf, CAM_ERRBUF_SIZE, 
+			 "%s: failed to issue unit reprobe request", func_name );
+		close(fd);
+		return(-1);
+	}
+
+	close(fd);
+	return 0;
+}
Index: lib/libcam/camlib.h
===================================================================
--- lib/libcam/camlib.h	(revision 291390)
+++ lib/libcam/camlib.h	(working copy)
@@ -146,6 +146,8 @@
 					struct cam_device *dst);
 int			cam_get_device(const char *path, char *dev_name,
 				       int devnamelen, int *unit);
+int			cam_reprobe_btl(path_id_t path_id, target_id_t target_id,
+				lun_id_t target_lun);
 
 /*
  * Buffer encoding/decoding routines, from the old SCSI library.
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},
@@ -3127,6 +3129,34 @@
 }
 
 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(cam_reprobe_btl(bus, target, lun));
+}
+
+static int
 rescan_or_reset_bus(path_id_t bus, int rescan)
 {
 	union ccb ccb, matchccb;
@@ -8685,6 +8715,7 @@
 #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 +9084,7 @@
 	 */
 	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 +9236,9 @@
 		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)
@@ -767,6 +767,7 @@
  * 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)
@@ -717,7 +717,41 @@
 		}
 		xpt_unlock_buses();
 		break;
+	}
+	case CAMUNITREPROBE: {
+		union ccb *inccb;
+		struct cam_path path;
+
+		inccb = (union ccb *)addr;
+
+		/*
+		 * Make sure a specific bus, target and lun were specified.
+		 */
+		if (inccb->ccb_h.path_id == CAM_BUS_WILDCARD ||
+			inccb->ccb_h.target_id == CAM_TARGET_WILDCARD ||
+		    inccb->ccb_h.target_lun == CAM_LUN_WILDCARD) {
+			error = EINVAL;
+			break;
 		}
+
+		/*
+		 * 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;
+	}
 	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");
 
Index: sys/cam/scsi/scsi_pass.h
===================================================================
--- sys/cam/scsi/scsi_pass.h	(revision 291390)
+++ sys/cam/scsi/scsi_pass.h	(working copy)
@@ -38,5 +38,6 @@
  */
 #define CAMIOCOMMAND	_IOWR(CAM_VERSION, 2, union ccb)
 #define CAMGETPASSTHRU	_IOWR(CAM_VERSION, 3, union ccb)
+#define CAMUNITREPROBE	_IOWR(CAM_VERSION, 4, union ccb)
 
 #endif