diff --git a/Assemble.c b/Assemble.c
index 47b8839..4966a79 100644
--- a/Assemble.c
+++ b/Assemble.c
@@ -263,6 +263,13 @@ int Assemble(struct supertype *st, char *mddev,
 				fprintf(stderr, Name ": no recogniseable superblock on %s\n",
 					devname);
 			tmpdev->used = 2;
+		} else if (auto_assem && st == NULL &&
+			   !conf_test_metadata(tst->ss->name)) {
+			if (report_missmatch)
+				fprintf(stderr, Name ": %s has metadata type %s for which "
+					"auto-assembly is disabled\n",
+					devname, tst->ss->name);
+			tmpdev->used = 2;
 		} else if (tst->ss->load_super(tst,dfd, NULL)) {
 			if (report_missmatch)
 				fprintf( stderr, Name ": no RAID superblock on %s\n",
diff --git a/Incremental.c b/Incremental.c
index 5849d39..7d6de98 100644
--- a/Incremental.c
+++ b/Incremental.c
@@ -220,6 +220,15 @@ int Incremental(char *devname, int verbose, int runstop,
 		return 1;
 	}
 
+	if (!match && !conf_test_metadata(st->ss->name)) {
+		if (verbose >= 1)
+			fprintf(stderr, Name
+				": %s has metadata type %s for which "
+				"auto-assembly is disabled\n",
+				devname, st->ss->name);
+		return 1;
+	}
+
 	/* 3a/ if not, check for homehost match.  If no match, continue
 	 * but don't trust the 'name' in the array. Thus a 'random' minor
 	 * number will be assigned, and the device name will be based
diff --git a/config.c b/config.c
index 66c3964..0d5b3f9 100644
--- a/config.c
+++ b/config.c
@@ -56,7 +56,7 @@
  *  with a key word, and not be indented, or must start with a
  *  non-key-word and must be indented.
  *
- * Keywords are DEVICE and ARRAY
+ * Keywords are DEVICE and ARRAY ... and several others.
  * DEV{ICE} introduces some devices that might contain raid components.
  * e.g.
  *   DEV style=0 /dev/sda* /dev/hd*
@@ -79,7 +79,8 @@
 char DefaultConfFile[] = CONFFILE;
 char DefaultAltConfFile[] = CONFFILE2;
 
-enum linetype { Devices, Array, Mailaddr, Mailfrom, Program, CreateDev, Homehost, LTEnd };
+enum linetype { Devices, Array, Mailaddr, Mailfrom, Program, CreateDev,
+		Homehost, AutoMode, LTEnd };
 char *keywords[] = {
 	[Devices]  = "devices",
 	[Array]    = "array",
@@ -88,6 +89,7 @@ char *keywords[] = {
 	[Program]  = "program",
 	[CreateDev]= "create",
 	[Homehost] = "homehost",
+	[AutoMode] = "auto",
 	[LTEnd]    = NULL
 };
 
@@ -639,6 +641,16 @@ void homehostline(char *line)
 	}
 }
 
+static char *auto_options = NULL;
+void autoline(char *line)
+{
+	if (auto_options) {
+		fprintf(stderr, Name ": AUTO line may only be give once."
+			"  Subsequent lines ignored\n");
+		return;
+	}
+	auto_options = line;		
+}
 
 int loaded = 0;
 
@@ -709,6 +721,9 @@ void load_conffile(void)
 		case Homehost:
 			homehostline(line);
 			break;
+		case AutoMode:
+			autoline(line);
+			break;
 		default:
 			fprintf(stderr, Name ": Unknown keyword %s\n", line);
 		}
@@ -832,6 +847,52 @@ int conf_test_dev(char *devname)
 	return 0;
 }
 
+int conf_test_metadata(const char *version)
+{
+	/* Check if the given metadata version is allowed
+	 * to be auto-assembled.
+	 * The default is 'yes' but the 'auto' line might over-ride that.
+	 * Word in auto_options are processed in order with the first
+	 * match winning.
+	 * word can be:
+	 *   +version   - that version can be assembled
+	 *   -version   - that version cannot be auto-assembled
+	 *   yes or +all - any other version can be assembled
+	 *   no or -all  - no other version can be assembled.
+	 */
+	char *w;
+	load_conffile();
+	if (!auto_options)
+		return 1;
+	for (w = dl_next(auto_options); w != auto_options; w = dl_next(w)) {
+		int rv;
+		if (strcasecmp(w, "yes") == 0)
+			return 1;
+		if (strcasecmp(w, "no") == 0)
+			return 0;
+		if (w[0] == '+')
+			rv = 1;
+		else if (w[0] == '-')
+			rv = 0;
+		else continue;
+
+		if (strcasecmp(w+1, "all") == 0)
+			return rv;
+		if (strcasecmp(w+1, version) == 0)
+			return rv;
+		/* allow  '0' to match version '0.90'
+		 * and 1 or 1.whatever to match version '1.x'
+		 */
+		if (version[1] == '.' &&
+		    strlen(w+1) == 1 &&
+		    w[1] == version[0])
+			return rv;
+		if (version[1] == '.' && version[2] == 'x' &&
+		    strncmp(w+1, version, 2) == 0)
+			return rv;
+	}
+	return 1;
+}
 
 int match_oneof(char *devices, char *devname)
 {
diff --git a/mdadm.conf.5 b/mdadm.conf.5
index 7654f5f..f69c0b0 100644
--- a/mdadm.conf.5
+++ b/mdadm.conf.5
@@ -339,6 +339,39 @@ When arrays are created, this host name will be stored in the
 metadata.  When arrays are assembled using auto-assembly, only arrays
 with this host name stored in the metadata will be considered.
 
+.TP
+.B AUTO
+A list of names of metadata format can be given, each preceded by a
+plus or minus sign.  Also the word
+.I all
+preceded by plus or minus is allowed and is usually last.
+
+When
+.I mdadm
+is auto-assembling an array, with via
+.I --assemble
+or
+.I --incremental
+and it finds metadata of a given type, it checks that metadata type
+against those listed in this line.  The first match wins, where
+.I all
+matches anything.
+If a match is found that was preceded by a plus sign, the auto
+assembly is allowed.  If the match was preceded by a minus sign, the
+auto assembly is disallowed.  If no match is found, the auto assembly
+is allowed.
+
+This can be used to disable all auto-assembly (so that only arrays
+explicitly listed in mdadm.conf or on the command line are assembled),
+or to disable assembly of certain metadata types which might be
+handled by other software.
+
+The known metadata types are
+.BR 0.90 ,
+.BR 1.x ,
+.BR ddf ,
+.BR imsm .
+
 .SH EXAMPLE
 DEVICE /dev/sd[bcdjkl]1
 .br
@@ -385,6 +418,8 @@ PROGRAM /usr/sbin/handle\-mdadm\-events
 CREATE group=system mode=0640 auto=part\-8
 .br
 HOMEHOST <system>
+.br
+AUTO +1.x -all
 
 .SH SEE ALSO
 .BR mdadm (8),
diff --git a/mdadm.h b/mdadm.h
index 251f9a1..1f47be3 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -789,6 +789,7 @@ extern int parse_auto(char *str, char *msg, int config);
 extern mddev_ident_t conf_get_ident(char *dev);
 extern mddev_dev_t conf_get_devs(void);
 extern int conf_test_dev(char *devname);
+extern int conf_test_metadata(const char *version);
 extern struct createinfo *conf_get_create_info(void);
 extern void set_conffile(char *file);
 extern char *conf_get_mailaddr(void);
diff --git a/super1.c b/super1.c
index d1b8a94..679120f 100644
--- a/super1.c
+++ b/super1.c
@@ -1652,5 +1652,5 @@ struct superswitch super1 = {
 #else
 	.swapuuid = 1,
 #endif
-	.name = "1.0",
+	.name = "1.x",
 };