diff --git a/Tools/check_submodules.sh b/Tools/check_submodules.sh
index 0c03396e7b..3904a27753 100755
--- a/Tools/check_submodules.sh
+++ b/Tools/check_submodules.sh
@@ -73,8 +73,8 @@ then
 		exit 1
 	fi
 else
-	git submodule init
-	git submodule update
+	git submodule init;
+	git submodule update;
 fi
 
 exit 0
diff --git a/src/drivers/drv_tone_alarm.h b/src/drivers/drv_tone_alarm.h
index b7981e9c4b..19f792d19c 100644
--- a/src/drivers/drv_tone_alarm.h
+++ b/src/drivers/drv_tone_alarm.h
@@ -149,6 +149,7 @@ enum {
 	TONE_GPS_WARNING_TUNE,
 	TONE_ARMING_FAILURE_TUNE,
 	TONE_PARACHUTE_RELEASE_TUNE,
+	TONE_EKF_WARNING_TUNE,
 	TONE_NUMBER_OF_TUNES
 };
 
diff --git a/src/drivers/stm32/tone_alarm/tone_alarm.cpp b/src/drivers/stm32/tone_alarm/tone_alarm.cpp
index 810f4aacc4..03c7bd399f 100644
--- a/src/drivers/stm32/tone_alarm/tone_alarm.cpp
+++ b/src/drivers/stm32/tone_alarm/tone_alarm.cpp
@@ -336,6 +336,7 @@ ToneAlarm::ToneAlarm() :
 	_default_tunes[TONE_GPS_WARNING_TUNE] = "MFT255L4AAAL1F#";					//gps warning slow
 	_default_tunes[TONE_ARMING_FAILURE_TUNE] = "MFT255L4<<<BAP";
 	_default_tunes[TONE_PARACHUTE_RELEASE_TUNE] = "MFT255L16agagagag";			// parachute release
+	_default_tunes[TONE_EKF_WARNING_TUNE] = "MFT255L8ddd#d#eeff";				// ekf warning
 
 	_tune_names[TONE_STARTUP_TUNE] = "startup";			// startup tune
 	_tune_names[TONE_ERROR_TUNE] = "error";				// ERROR tone
@@ -348,6 +349,7 @@ ToneAlarm::ToneAlarm() :
 	_tune_names[TONE_GPS_WARNING_TUNE] = "gps_warning";	            // gps warning
 	_tune_names[TONE_ARMING_FAILURE_TUNE] = "arming_failure";            //fail to arm
 	_tune_names[TONE_PARACHUTE_RELEASE_TUNE] = "parachute_release";	// parachute release
+	_tune_names[TONE_EKF_WARNING_TUNE] = "ekf_warning";				// ekf warning
 }
 
 ToneAlarm::~ToneAlarm()
diff --git a/src/modules/ekf_att_pos_estimator/estimator_23states.cpp b/src/modules/ekf_att_pos_estimator/estimator_23states.cpp
index 768e0be350..3d504d3955 100644
--- a/src/modules/ekf_att_pos_estimator/estimator_23states.cpp
+++ b/src/modules/ekf_att_pos_estimator/estimator_23states.cpp
@@ -2773,7 +2773,7 @@ int AttPosEKF::CheckAndBound(struct ekf_status_report *last_error)
         ResetHeight();
         ResetStoredStates();
 
-        ret = 3;
+        ret = 0;
     }
 
     // Reset the filter if gyro offsets are excessive
diff --git a/src/modules/mavlink/mavlink_main.cpp b/src/modules/mavlink/mavlink_main.cpp
index 0c6f8c42f8..fbe09564bc 100644
--- a/src/modules/mavlink/mavlink_main.cpp
+++ b/src/modules/mavlink/mavlink_main.cpp
@@ -559,22 +559,39 @@ void Mavlink::mavlink_update_system(void)
 		_param_component_id = param_find("MAV_COMP_ID");
 		_param_system_type = param_find("MAV_TYPE");
 		_param_use_hil_gps = param_find("MAV_USEHILGPS");
-		_param_initialized = true;
 	}
 
 	/* update system and component id */
 	int32_t system_id;
 	param_get(_param_system_id, &system_id);
 
-	if (system_id > 0 && system_id < 255) {
-		mavlink_system.sysid = system_id;
-	}
-
 	int32_t component_id;
 	param_get(_param_component_id, &component_id);
 
-	if (component_id > 0 && component_id < 255) {
-		mavlink_system.compid = component_id;
+
+	/* only allow system ID and component ID updates
+	 * after reboot - not during operation */
+	if (!_param_initialized) {
+		if (system_id > 0 && system_id < 255) {
+			mavlink_system.sysid = system_id;
+		}
+
+		if (component_id > 0 && component_id < 255) {
+			mavlink_system.compid = component_id;
+		}
+
+		_param_initialized = true;
+	}
+
+	/* warn users that they need to reboot to take this
+	 * into effect
+	 */
+	if (system_id != mavlink_system.sysid) {
+		send_statustext_critical("Save params and reboot to change SYSID");
+	}
+
+	if (component_id != mavlink_system.compid) {
+		send_statustext_critical("Save params and reboot to change COMPID");
 	}
 
 	int32_t system_type;
diff --git a/src/modules/uORB/topics/vehicle_status.h b/src/modules/uORB/topics/vehicle_status.h
index e0072b52d5..707abb5458 100644
--- a/src/modules/uORB/topics/vehicle_status.h
+++ b/src/modules/uORB/topics/vehicle_status.h
@@ -188,7 +188,7 @@ struct vehicle_status_s {
 	bool condition_system_sensors_initialized;
 	bool condition_system_returned_to_home;
 	bool condition_auto_mission_available;
-	bool condition_global_position_valid;		/**< set to true by the commander app if the quality of the gps signal is good enough to use it in the position estimator */
+	bool condition_global_position_valid;		/**< set to true by the commander app if the quality of the position estimate is good enough to use it for navigation */
 	bool condition_launch_position_valid;		/**< indicates a valid launch position */
 	bool condition_home_position_valid;		/**< indicates a valid home position (a valid home position is not always a valid launch) */
 	bool condition_local_position_valid;
diff --git a/uavcan b/uavcan
index dca2611c31..d84fc8a846 160000
--- a/uavcan
+++ b/uavcan
@@ -1 +1 @@
-Subproject commit dca2611c3186eaa1cac42557f07b013e2dc633d3
+Subproject commit d84fc8a84678d93f97f93b240c81472797ca5889