diff --git a/scst/include/scst.h b/scst/include/scst.h
index 7dc48ff3e..5588de7d2 100644
--- a/scst/include/scst.h
+++ b/scst/include/scst.h
@@ -2076,6 +2076,8 @@ struct scst_acg {
 
 	struct kobject *luns_kobj;
 	struct kobject *initiators_kobj;
+
+	unsigned int addr_method;
 };
 
 /*
diff --git a/scst/src/scst_lib.c b/scst/src/scst_lib.c
index d5976ce10..337972f0e 100644
--- a/scst/src/scst_lib.c
+++ b/scst/src/scst_lib.c
@@ -1107,7 +1107,7 @@ static struct scst_aen *scst_alloc_aen(struct scst_session *sess,
 	aen->sess = sess;
 	scst_sess_get(sess);
 
-	aen->lun = scst_pack_lun(unpacked_lun);
+	aen->lun = scst_pack_lun(unpacked_lun, sess->acg->addr_method);
 
 out:
 	TRACE_EXIT_HRES((unsigned long)aen);
@@ -2162,6 +2162,8 @@ struct scst_acg *scst_alloc_add_acg(struct scst_tgt *tgt,
 		goto out_free;
 	}
 
+	acg->addr_method = SCST_LUN_ADDR_METHOD_PERIPHERAL;
+
 #ifdef CONFIG_SCST_PROC
 	TRACE_DBG("Adding acg %s to scst_acg_list", acg_name);
 	list_add_tail(&acg->acg_list_entry, &scst_acg_list);
@@ -4259,13 +4261,25 @@ out:
 }
 EXPORT_SYMBOL(scst_get_cdb_info);
 
-/* Packs SCST LUN back to SCSI form using peripheral device addressing method */
-uint64_t scst_pack_lun(const uint64_t lun)
+/* Packs SCST LUN back to SCSI form */
+uint64_t scst_pack_lun(const uint64_t lun, unsigned int addr_method)
 {
-	uint64_t res;
+
+	uint64_t res = 0;
 	uint16_t *p = (uint16_t *)&res;
 
 	res = lun;
+
+	if ((addr_method == SCST_LUN_ADDR_METHOD_FLAT) && (lun != 0)) {
+		/*
+		 * Flat space: luns other than 0 should use flat space
+		 * addressing method.
+		 */
+		*p = 0x7fff & *p;
+		*p = 0x4000 | *p;
+	}
+	/* Default is to use peripheral device addressing mode */
+
 	*p = cpu_to_be16(*p);
 
 	TRACE_EXIT_HRES((unsigned long)res);
diff --git a/scst/src/scst_priv.h b/scst/src/scst_priv.h
index 8c7fa1370..8e9a90eef 100644
--- a/scst/src/scst_priv.h
+++ b/scst/src/scst_priv.h
@@ -125,6 +125,10 @@ extern unsigned long scst_trace_flag;
 
 #define SCST_TGT_RETRY_TIMEOUT               (3/2*HZ)
 
+/* Definitions of symbolic constants for LUN addressing method */
+#define SCST_LUN_ADDR_METHOD_PERIPHERAL	0
+#define SCST_LUN_ADDR_METHOD_FLAT 	1
+
 extern unsigned int scst_max_dev_cmd_mem;
 
 extern mempool_t *scst_mgmt_mempool;
@@ -417,7 +421,7 @@ int scst_alloc_space(struct scst_cmd *cmd);
 int scst_lib_init(void);
 void scst_lib_exit(void);
 
-uint64_t scst_pack_lun(const uint64_t lun);
+uint64_t scst_pack_lun(const uint64_t lun, unsigned int addr_method);
 uint64_t scst_unpack_lun(const uint8_t *lun, int len);
 
 struct scst_mgmt_cmd *scst_alloc_mgmt_cmd(gfp_t gfp_mask);
diff --git a/scst/src/scst_proc.c b/scst/src/scst_proc.c
index 4b1f36acf..71914271f 100644
--- a/scst/src/scst_proc.c
+++ b/scst/src/scst_proc.c
@@ -37,7 +37,7 @@
 static int scst_proc_init_groups(void);
 static void scst_proc_cleanup_groups(void);
 static int scst_proc_assign_handler(char *buf);
-static int scst_proc_group_add(const char *p);
+static int scst_proc_group_add(const char *p, unsigned int addr_method);
 static int scst_proc_del_free_acg(struct scst_acg *acg, int remove_proc);
 
 static struct scst_proc_data scst_version_proc_data;
@@ -45,6 +45,7 @@ static struct scst_proc_data scst_help_proc_data;
 static struct scst_proc_data scst_sgv_proc_data;
 static struct scst_proc_data scst_groups_names_proc_data;
 static struct scst_proc_data scst_groups_devices_proc_data;
+static struct scst_proc_data scst_groups_addr_method_proc_data;
 static struct scst_proc_data scst_sessions_proc_data;
 static struct scst_proc_data scst_dev_handler_type_proc_data;
 static struct scst_proc_data scst_tgt_proc_data;
@@ -67,6 +68,7 @@ static struct scst_proc_data scst_dev_handler_proc_data;
 #define SCST_PROC_GROUPS_ENTRY_NAME		"groups"
 #define SCST_PROC_GROUPS_DEVICES_ENTRY_NAME	"devices"
 #define SCST_PROC_GROUPS_USERS_ENTRY_NAME	"names"
+#define SCST_PROC_GROUPS_ADDR_METHOD_ENTRY_NAME "addr_method"
 
 #ifdef CONFIG_SCST_MEASURE_LATENCY
 #define SCST_PROC_LAT_ENTRY_NAME		"latency"
@@ -127,7 +129,7 @@ static struct scst_trace_log scst_proc_local_trace_tbl[] = {
 static char *scst_proc_help_string =
 "   echo \"assign H:C:I:L HANDLER_NAME\" >/proc/scsi_tgt/scsi_tgt\n"
 "\n"
-"   echo \"add_group GROUP_NAME\" >/proc/scsi_tgt/scsi_tgt\n"
+"   echo \"add_group GROUP_NAME [FLAT]\" >/proc/scsi_tgt/scsi_tgt\n"
 "   echo \"del_group GROUP_NAME\" >/proc/scsi_tgt/scsi_tgt\n"
 "   echo \"rename_group OLD_NAME NEW_NAME\" >/proc/scsi_tgt/scsi_tgt\n"
 "\n"
@@ -811,17 +813,30 @@ static int scst_proc_group_add_tree(struct scst_acg *acg, const char *name)
 		goto out;
 	}
 
+	scst_groups_addr_method_proc_data.data = acg;
+	generic = scst_create_proc_entry(acg->acg_proc_root,
+				 SCST_PROC_GROUPS_ADDR_METHOD_ENTRY_NAME,
+				 &scst_groups_addr_method_proc_data);
+	if (!generic) {
+		PRINT_ERROR("Cannot init /proc/%s/%s/%s/%s",
+		       SCST_PROC_ENTRY_NAME,
+		       SCST_PROC_GROUPS_ENTRY_NAME,
+		       name, SCST_PROC_GROUPS_ADDR_METHOD_ENTRY_NAME);
+		res = -ENOMEM;
+		goto out_remove;
+	}
+
 	scst_groups_devices_proc_data.data = acg;
 	generic = scst_create_proc_entry(acg->acg_proc_root,
 					 SCST_PROC_GROUPS_DEVICES_ENTRY_NAME,
 					 &scst_groups_devices_proc_data);
 	if (!generic) {
-		PRINT_ERROR("cannot init /proc/%s/%s/%s/%s",
+		PRINT_ERROR("Cannot init /proc/%s/%s/%s/%s",
 			       SCST_PROC_ENTRY_NAME,
 			       SCST_PROC_GROUPS_ENTRY_NAME,
 			       name, SCST_PROC_GROUPS_DEVICES_ENTRY_NAME);
 		res = -ENOMEM;
-		goto out_remove;
+		goto out_remove0;
 	}
 
 	scst_groups_names_proc_data.data = acg;
@@ -829,7 +844,7 @@ static int scst_proc_group_add_tree(struct scst_acg *acg, const char *name)
 					 SCST_PROC_GROUPS_USERS_ENTRY_NAME,
 					 &scst_groups_names_proc_data);
 	if (!generic) {
-		PRINT_ERROR("cannot init /proc/%s/%s/%s/%s",
+		PRINT_ERROR("Cannot init /proc/%s/%s/%s/%s",
 			       SCST_PROC_ENTRY_NAME,
 			       SCST_PROC_GROUPS_ENTRY_NAME,
 			       name, SCST_PROC_GROUPS_USERS_ENTRY_NAME);
@@ -845,6 +860,9 @@ out_remove1:
 	remove_proc_entry(SCST_PROC_GROUPS_DEVICES_ENTRY_NAME,
 			  acg->acg_proc_root);
 
+out_remove0:
+	remove_proc_entry(SCST_PROC_GROUPS_ADDR_METHOD_ENTRY_NAME,
+			  acg->acg_proc_root);
 out_remove:
 	remove_proc_entry(name, scst_proc_groups_root);
 	goto out;
@@ -855,9 +873,9 @@ static void scst_proc_del_acg_tree(struct proc_dir_entry *acg_proc_root,
 {
 	TRACE_ENTRY();
 
+	remove_proc_entry(SCST_PROC_GROUPS_ADDR_METHOD_ENTRY_NAME, acg_proc_root);
 	remove_proc_entry(SCST_PROC_GROUPS_USERS_ENTRY_NAME, acg_proc_root);
-	remove_proc_entry(SCST_PROC_GROUPS_DEVICES_ENTRY_NAME,
-				acg_proc_root);
+	remove_proc_entry(SCST_PROC_GROUPS_DEVICES_ENTRY_NAME, acg_proc_root);
 	remove_proc_entry(name, scst_proc_groups_root);
 
 	TRACE_EXIT();
@@ -865,7 +883,7 @@ static void scst_proc_del_acg_tree(struct proc_dir_entry *acg_proc_root,
 }
 
 /* The activity supposed to be suspended and scst_mutex held */
-static int scst_proc_group_add(const char *p)
+static int scst_proc_group_add(const char *p, unsigned int addr_method)
 {
 	int res = 0, len = strlen(p) + 1;
 	struct scst_acg *acg;
@@ -886,6 +904,8 @@ static int scst_proc_group_add(const char *p)
 		goto out_free;
 	}
 
+	acg->addr_method = addr_method;
+
 	res = scst_proc_group_add_tree(acg, p);
 	if (res != 0)
 		goto out_free_acg;
@@ -1536,8 +1556,9 @@ static ssize_t scst_proc_scsi_tgt_gen_write(struct file *file,
 					size_t length, loff_t *off)
 {
 	int res, rc = 0, action;
-	char *buffer, *p, *pp;
+	char *buffer, *p, *pp, *ppp;
 	struct scst_acg *a, *acg = NULL;
+	unsigned int addr_method = SCST_LUN_ADDR_METHOD_PERIPHERAL;
 
 	TRACE_ENTRY();
 
@@ -1566,7 +1587,7 @@ static ssize_t scst_proc_scsi_tgt_gen_write(struct file *file,
 	}
 
 	/*
-	 * Usage: echo "add_group GROUP_NAME" >/proc/scsi_tgt/scsi_tgt
+	 * Usage: echo "add_group GROUP_NAME [FLAT]" >/proc/scsi_tgt/scsi_tgt
 	 *   or   echo "del_group GROUP_NAME" >/proc/scsi_tgt/scsi_tgt
 	 *   or   echo "rename_group OLD_NAME NEW_NAME" >/proc/scsi_tgt/scsi_tgt"
 	 *   or   echo "assign H:C:I:L HANDLER_NAME" >/proc/scsi_tgt/scsi_tgt
@@ -1603,6 +1624,9 @@ static ssize_t scst_proc_scsi_tgt_gen_write(struct file *file,
 
 	res = length;
 
+	while (isspace(*p) && *p != '\0')
+		p++;
+
 	switch (action) {
 	case SCST_PROC_ACTION_ADD_GROUP:
 	case SCST_PROC_ACTION_DEL_GROUP:
@@ -1618,6 +1642,29 @@ static ssize_t scst_proc_scsi_tgt_gen_write(struct file *file,
 			if (*pp != '\0') {
 				switch (action) {
 				case SCST_PROC_ACTION_ADD_GROUP:
+					ppp = pp;
+					while (!isspace(*ppp) && *ppp != '\0')
+						ppp++;
+					if (*ppp != '\0') {
+						*ppp = '\0';
+					   ppp++;
+					   while (isspace(*ppp) && *ppp != '\0')
+						ppp++;
+					   if (*ppp != '\0') {
+						PRINT_ERROR("%s", "Too many "
+							"arguments");
+							res = -EINVAL;
+							goto out_up_free;
+					   }
+					}
+					if (strcasecmp(pp, "FLAT") != 0) {
+						PRINT_ERROR("Unexpected "
+							"argument %s", pp);
+						res = -EINVAL;
+						goto out_up_free;
+					} else
+						addr_method = SCST_LUN_ADDR_METHOD_FLAT;
+					break;
 				case SCST_PROC_ACTION_DEL_GROUP:
 					PRINT_ERROR("%s", "Too many "
 						"arguments");
@@ -1650,7 +1697,7 @@ static ssize_t scst_proc_scsi_tgt_gen_write(struct file *file,
 				res = -EINVAL;
 				goto out_up_free;
 			}
-			rc = scst_proc_group_add(p);
+			rc = scst_proc_group_add(p, addr_method);
 			break;
 		case SCST_PROC_ACTION_DEL_GROUP:
 			if (acg == NULL) {
@@ -2396,6 +2443,40 @@ static struct scst_proc_data scst_groups_names_proc_data = {
 	.show = scst_groups_names_show,
 };
 
+static int scst_groups_addr_method_show(struct seq_file *seq, void *v)
+{
+	int res = 0;
+	struct scst_acg *acg = (struct scst_acg *)seq->private;
+
+	TRACE_ENTRY();
+
+	if (mutex_lock_interruptible(&scst_mutex) != 0) {
+		res = -EINTR;
+		goto out;
+	}
+
+	switch (acg->addr_method) {
+	case SCST_LUN_ADDR_METHOD_FLAT:
+		seq_printf(seq, "%s\n", "FLAT");
+		break;
+	case SCST_LUN_ADDR_METHOD_PERIPHERAL:
+		seq_printf(seq, "%s\n", "PERIPHERAL");
+		break;
+	default:
+		seq_printf(seq, "%s\n", "UNKNOWN");
+		break;
+	}
+
+	mutex_unlock(&scst_mutex);
+
+out:
+	TRACE_EXIT_RES(res);
+	return res;
+}
+static struct scst_proc_data scst_groups_addr_method_proc_data = {
+	SCST_DEF_RW_SEQ_OP(NULL)
+	.show = scst_groups_addr_method_show,
+};
 static int scst_groups_devices_show(struct seq_file *seq, void *v)
 {
 	int res = 0;
diff --git a/scst/src/scst_sysfs.c b/scst/src/scst_sysfs.c
index 28fa2221f..3872e6fc9 100644
--- a/scst/src/scst_sysfs.c
+++ b/scst/src/scst_sysfs.c
@@ -106,6 +106,12 @@ static ssize_t scst_luns_mgmt_show(struct kobject *kobj,
 static ssize_t scst_luns_mgmt_store(struct kobject *kobj,
 				    struct kobj_attribute *attr,
 				    const char *buf, size_t count);
+static ssize_t scst_tgt_addr_method_show(struct kobject *kobj,
+				   struct kobj_attribute *attr,
+				   char *buf);
+static ssize_t scst_tgt_addr_method_store(struct kobject *kobj,
+				    struct kobj_attribute *attr,
+				    const char *buf, size_t count);
 static ssize_t scst_ini_group_mgmt_show(struct kobject *kobj,
 				   struct kobj_attribute *attr,
 				   char *buf);
@@ -127,6 +133,12 @@ static ssize_t scst_acg_ini_mgmt_show(struct kobject *kobj,
 static ssize_t scst_acg_ini_mgmt_store(struct kobject *kobj,
 				    struct kobj_attribute *attr,
 				    const char *buf, size_t count);
+static ssize_t scst_acg_addr_method_show(struct kobject *kobj,
+				   struct kobj_attribute *attr,
+				   char *buf);
+static ssize_t scst_acg_addr_method_store(struct kobject *kobj,
+				    struct kobj_attribute *attr,
+				    const char *buf, size_t count);
 static ssize_t scst_acn_file_show(struct kobject *kobj,
 	struct kobj_attribute *attr, char *buf);
 
@@ -513,10 +525,18 @@ static struct kobj_attribute scst_ini_group_mgmt =
 	__ATTR(mgmt, S_IRUGO | S_IWUSR, scst_ini_group_mgmt_show,
 	       scst_ini_group_mgmt_store);
 
+static struct kobj_attribute scst_tgt_addr_method =
+	__ATTR(addr_method, S_IRUGO | S_IWUSR, scst_tgt_addr_method_show,
+	       scst_tgt_addr_method_store);
+
 static struct kobj_attribute scst_rel_tgt_id =
 	__ATTR(rel_tgt_id, S_IRUGO | S_IWUSR, scst_rel_tgt_id_show,
 	       scst_rel_tgt_id_store);
 
+static struct kobj_attribute scst_acg_addr_method =
+	__ATTR(addr_method, S_IRUGO | S_IWUSR, scst_acg_addr_method_show,
+		scst_acg_addr_method_store);
+
 static ssize_t scst_tgt_enable_show(struct kobject *kobj,
 	struct kobj_attribute *attr, char *buf)
 {
@@ -672,6 +692,14 @@ int scst_create_tgt_sysfs(struct scst_tgt *tgt)
 		goto out;
 	}
 
+	retval = sysfs_create_file(&tgt->tgt_kobj,
+			&scst_tgt_addr_method.attr);
+	if (retval != 0) {
+		PRINT_ERROR("Can't add attribute %s for tgt %s",
+			scst_tgt_addr_method.attr.name, tgt->tgt_name);
+		goto out;
+	}
+
 	pattr = tgt->tgtt->tgt_attrs;
 	if (pattr != NULL) {
 		while (*pattr != NULL) {
@@ -1652,12 +1680,76 @@ static ssize_t scst_luns_mgmt_store(struct kobject *kobj,
 
 	tgt = container_of(kobj->parent, struct scst_tgt, tgt_kobj);
 	acg = tgt->default_acg;
+
 	res = __scst_luns_mgmt_store(acg, kobj, buf, count);
 
 	TRACE_EXIT_RES(res);
 	return res;
 }
 
+static ssize_t __scst_acg_addr_method_show(struct scst_acg *acg, char *buf)
+{
+	int res;
+
+	switch (acg->addr_method) {
+	case SCST_LUN_ADDR_METHOD_FLAT:
+		res = sprintf(buf, "FLAT\n%s\n", SCST_SYSFS_KEY_MARK);
+		break;
+	case SCST_LUN_ADDR_METHOD_PERIPHERAL:
+		res = sprintf(buf, "PERIPHERAL\n");
+		break;
+	default:
+		res = sprintf(buf, "UNKNOWN\n");
+		break;
+	}
+
+	return res;
+}
+
+static ssize_t __scst_acg_addr_method_store(struct scst_acg *acg,
+	const char *buf, size_t count)
+{
+	int res = count;
+
+	if (strncasecmp(buf, "FLAT", min_t(int, 4, count)) == 0)
+		acg->addr_method = SCST_LUN_ADDR_METHOD_FLAT;
+	else if (strncasecmp(buf, "PERIPHERAL", min_t(int, 10, count)) == 0)
+		acg->addr_method = SCST_LUN_ADDR_METHOD_PERIPHERAL;
+	else {
+		PRINT_ERROR("Unknown address method %s", buf);
+		res = -EINVAL;
+	}
+	return res;
+}
+
+static ssize_t scst_tgt_addr_method_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	struct scst_acg *acg;
+	struct scst_tgt *tgt;
+
+	tgt = container_of(kobj, struct scst_tgt, tgt_kobj);
+	acg = tgt->default_acg;
+
+	return __scst_acg_addr_method_show(acg, buf);
+}
+
+static ssize_t scst_tgt_addr_method_store(struct kobject *kobj,
+	struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	int res;
+	struct scst_acg *acg;
+	struct scst_tgt *tgt;
+
+	tgt = container_of(kobj, struct scst_tgt, tgt_kobj);
+	acg = tgt->default_acg;
+
+	res = __scst_acg_addr_method_store(acg, buf, count);
+
+	TRACE_EXIT_RES(res);
+	return res;
+}
+
 static int scst_create_acg_sysfs(struct scst_tgt *tgt,
 	struct scst_acg *acg)
 {
@@ -1705,6 +1797,14 @@ static int scst_create_acg_sysfs(struct scst_tgt *tgt,
 			scst_acg_ini_mgmt.attr.name, tgt->tgt_name);
 		goto out;
 	}
+
+	retval = sysfs_create_file(&acg->acg_kobj, &scst_acg_addr_method.attr);
+	if (retval != 0) {
+		PRINT_ERROR("Can't add tgt attr %s for tgt %s",
+			scst_acg_addr_method.attr.name,
+				tgt->tgt_name);
+		goto out;
+	}
 out:
 	TRACE_EXIT_RES(retval);
 	return retval;
@@ -1732,13 +1832,35 @@ void scst_acg_sysfs_put(struct scst_acg *acg)
 	return;
 }
 
+static ssize_t scst_acg_addr_method_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	struct scst_acg *acg;
+
+	acg = container_of(kobj, struct scst_acg, acg_kobj);
+
+	return __scst_acg_addr_method_show(acg, buf);
+}
+
+static ssize_t scst_acg_addr_method_store(struct kobject *kobj,
+	struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	int res;
+	struct scst_acg *acg;
+
+	acg = container_of(kobj, struct scst_acg, acg_kobj);
+
+	res = __scst_acg_addr_method_store(acg, buf, count);
+
+	TRACE_EXIT_RES(res);
+	return res;
+}
+
 static ssize_t scst_ini_group_mgmt_show(struct kobject *kobj,
 	struct kobj_attribute *attr, char *buf)
 {
-	static char *help = "Usage: echo \"create GROUP_NAME\" "
-					">mgmt\n"
-			    "       echo \"del GROUP_NAME\" "
-					">mgmt\n";
+	static char *help = "Usage: echo \"create GROUP_NAME\" >mgmt\n"
+			    "       echo \"del GROUP_NAME\" >mgmt\n";
 
 	return sprintf(buf, help);
 }
diff --git a/scst/src/scst_targ.c b/scst/src/scst_targ.c
index be0231317..a8d65f84f 100644
--- a/scst/src/scst_targ.c
+++ b/scst/src/scst_targ.c
@@ -1481,8 +1481,15 @@ static int scst_report_luns_local(struct scst_cmd *cmd)
 						buffer_size);
 					goto out_put_hw_err;
 				}
-				buffer[offs] = (tgt_dev->lun >> 8) & 0xff;
-				buffer[offs+1] = tgt_dev->lun & 0xff;
+				if ((cmd->sess->acg->addr_method == SCST_LUN_ADDR_METHOD_FLAT) &&
+				    (tgt_dev->lun != 0)) {
+					buffer[offs] = (tgt_dev->lun >> 8) & 0x3f;
+					buffer[offs] = buffer[offs] | 0x40;
+					buffer[offs+1] = tgt_dev->lun & 0xff;
+				} else {
+					buffer[offs] = (tgt_dev->lun >> 8) & 0xff;
+					buffer[offs+1] = tgt_dev->lun & 0xff;
+				}
 				offs += 8;
 			}
 inc_dev_cnt: