Index: head/sbin/camcontrol/camcontrol.8
===================================================================
--- head/sbin/camcontrol/camcontrol.8
+++ head/sbin/camcontrol/camcontrol.8
@@ -78,6 +78,7 @@
 .Op Fl b
 .Op Fl h
 .Op Fl H
+.Op Fl l
 .Op Fl N
 .Op Fl q
 .Op Fl s
@@ -544,6 +545,11 @@
 .Fl b .
 .It Fl H
 Print out the device size in human readable (base 10, 1K == 1000) format.
+.It Fl l
+Skip sending the SCSI READ CAPACITY (10) command.
+Send only the SCSI READ CAPACITY (16) service action and report
+its results.
+When the two do not match, a quirk is needed to resolve the ambiguity.
 .It Fl N
 Print out the number of blocks in the device instead of the last logical
 block.
Index: head/sbin/camcontrol/camcontrol.c
===================================================================
--- head/sbin/camcontrol/camcontrol.c
+++ head/sbin/camcontrol/camcontrol.c
@@ -203,7 +203,7 @@
 	{"load", CAM_CMD_STARTSTOP, CAM_ARG_START_UNIT | CAM_ARG_EJECT, NULL},
 	{"eject", CAM_CMD_STARTSTOP, CAM_ARG_EJECT, NULL},
 	{"reportluns", CAM_CMD_REPORTLUNS, CAM_ARG_NONE, "clr:"},
-	{"readcapacity", CAM_CMD_READCAP, CAM_ARG_NONE, "bhHNqs"},
+	{"readcapacity", CAM_CMD_READCAP, CAM_ARG_NONE, "bhHlNqs"},
 	{"reprobe", CAM_CMD_REPROBE, CAM_ARG_NONE, NULL},
 #endif /* MINIMALISTIC */
 	{"rescan", CAM_CMD_RESCAN, CAM_ARG_NONE, NULL},
@@ -7162,7 +7162,7 @@
 		 char *combinedopt, int task_attr, int retry_count, int timeout)
 {
 	union ccb *ccb;
-	int blocksizeonly, humanize, numblocks, quiet, sizeonly, baseten;
+	int blocksizeonly, humanize, numblocks, quiet, sizeonly, baseten, longonly;
 	struct scsi_read_capacity_data rcap;
 	struct scsi_read_capacity_data_long rcaplong;
 	uint64_t maxsector;
@@ -7172,6 +7172,7 @@
 
 	blocksizeonly = 0;
 	humanize = 0;
+	longonly = 0;
 	numblocks = 0;
 	quiet = 0;
 	sizeonly = 0;
@@ -7200,6 +7201,9 @@
 			humanize++;
 			baseten++;
 			break;
+		case 'l':
+			longonly++;
+			break;
 		case 'N':
 			numblocks++;
 			break;
@@ -7242,6 +7246,9 @@
 		goto bailout;
 	}
 
+	if (longonly != 0)
+		goto long_only;
+
 	scsi_read_capacity(&ccb->csio,
 			   /*retries*/ retry_count,
 			   /*cbfcnp*/ NULL,
@@ -7284,6 +7291,7 @@
 	if (maxsector != 0xffffffff)
 		goto do_print;
 
+long_only:
 	scsi_read_capacity_16(&ccb->csio,
 			      /*retries*/ retry_count,
 			      /*cbfcnp*/ NULL,
@@ -9515,7 +9523,7 @@
 "        camcontrol identify   [dev_id][generic args] [-v]\n"
 "        camcontrol reportluns [dev_id][generic args] [-c] [-l] [-r report]\n"
 "        camcontrol readcap    [dev_id][generic args] [-b] [-h] [-H] [-N]\n"
-"                              [-q] [-s]\n"
+"                              [-q] [-s] [-l]\n"
 "        camcontrol start      [dev_id][generic args]\n"
 "        camcontrol stop       [dev_id][generic args]\n"
 "        camcontrol load       [dev_id][generic args]\n"