diff --git a/ROMFS/px4fmu_common/init.d/rc.interface b/ROMFS/px4fmu_common/init.d/rc.interface
index f3761200a1..e305713377 100644
--- a/ROMFS/px4fmu_common/init.d/rc.interface
+++ b/ROMFS/px4fmu_common/init.d/rc.interface
@@ -97,6 +97,12 @@ then
 	fi
 fi
 
+# This is a FMUv2+ thing
+if ver hwcmp PX4FMU_V1
+then
+	set MIXER_AUX none
+fi
+
 if [ $MIXER_AUX != none ]
 then
 	#
diff --git a/ROMFS/px4fmu_common/init.d/rc.sensors b/ROMFS/px4fmu_common/init.d/rc.sensors
index 69d9e158dc..ff1a8092be 100644
--- a/ROMFS/px4fmu_common/init.d/rc.sensors
+++ b/ROMFS/px4fmu_common/init.d/rc.sensors
@@ -110,11 +110,6 @@ else
 	fi
 fi
 
-# Check for flow sensor
-if px4flow start &
-then
-fi
-
 #
 # Start sensors
 #
diff --git a/ROMFS/px4fmu_common/init.d/rcS b/ROMFS/px4fmu_common/init.d/rcS
index 74aef41601..efee9d3e5c 100644
--- a/ROMFS/px4fmu_common/init.d/rcS
+++ b/ROMFS/px4fmu_common/init.d/rcS
@@ -726,16 +726,22 @@ then
 # End of autostart
 fi
 
+# There is no further script processing, so we can free some RAM
+# XXX potentially unset all script variables.
+unset TUNE_ERR
+
 # Boot is complete, inform MAVLink app(s) that the system is now fully up and running
 mavlink boot_complete
 
+if ver hwcmp PX4FMU_V2
+then
+	# Check for flow sensor - as it is a background task, launch it last
+	px4flow start &
+fi
+
 if [ $EXIT_ON_END == yes ]
 then
 	echo "Exit from nsh"
 	exit
 fi
 unset EXIT_ON_END
-
-# There is no further processing, so we can free some RAM
-# XXX potentially unset all script variables.
-unset TUNE_ERR
diff --git a/mavlink/include/mavlink/v1.0 b/mavlink/include/mavlink/v1.0
index 645a0e1b1e..d23a551e10 160000
--- a/mavlink/include/mavlink/v1.0
+++ b/mavlink/include/mavlink/v1.0
@@ -1 +1 @@
-Subproject commit 645a0e1b1eb09efeeaa14cc18d2474628a31ab53
+Subproject commit d23a551e108d92c7a49a66d162cb9d542bbe6be1
diff --git a/nuttx-configs/px4fmu-v1/nsh/defconfig b/nuttx-configs/px4fmu-v1/nsh/defconfig
index 9ed1cbc53e..874615d3b2 100644
--- a/nuttx-configs/px4fmu-v1/nsh/defconfig
+++ b/nuttx-configs/px4fmu-v1/nsh/defconfig
@@ -261,7 +261,7 @@ CONFIG_STM32_USART=y
 # U[S]ART Configuration
 #
 # Hot fix for lost data
-CONFIG_STM32_RXDMA_BUFFER_SIZE_OVERRIDE=256
+CONFIG_STM32_RXDMA_BUFFER_SIZE_OVERRIDE=64
 # CONFIG_USART1_RS485 is not set
 # CONFIG_USART1_RXDMA is not set
 # CONFIG_USART2_RS485 is not set
diff --git a/src/drivers/px4flow/module.mk b/src/drivers/px4flow/module.mk
index ecd3e804a1..8d6964d103 100644
--- a/src/drivers/px4flow/module.mk
+++ b/src/drivers/px4flow/module.mk
@@ -41,4 +41,6 @@ SRCS		= px4flow.cpp
 
 MAXOPTIMIZATION	 = -Os
 
+MODULE_STACKSIZE = 1200
+
 EXTRACXXFLAGS = -Wno-attributes
diff --git a/src/drivers/px4io/px4io.cpp b/src/drivers/px4io/px4io.cpp
index a247c2596e..1259daceb1 100644
--- a/src/drivers/px4io/px4io.cpp
+++ b/src/drivers/px4io/px4io.cpp
@@ -1116,25 +1116,42 @@ PX4IO::task_main()
 				(void)io_reg_set(PX4IO_PAGE_SETUP, PX4IO_P_SETUP_PWM_REVERSE, pwm_invert_mask);
 
 				float trim_val;
-				param_t trim_parm;
+				param_t parm_handle;
 
-				trim_parm = param_find("TRIM_ROLL");
-				if (trim_parm != PARAM_INVALID) {
-					param_get(trim_parm, &trim_val);
+				parm_handle = param_find("TRIM_ROLL");
+				if (parm_handle != PARAM_INVALID) {
+					param_get(parm_handle, &trim_val);
 					(void)io_reg_set(PX4IO_PAGE_SETUP, PX4IO_P_SETUP_TRIM_ROLL, FLOAT_TO_REG(trim_val));
 				}
 
-				trim_parm = param_find("TRIM_PITCH");
-				if (trim_parm != PARAM_INVALID) {
-					param_get(trim_parm, &trim_val);
+				parm_handle = param_find("TRIM_PITCH");
+				if (parm_handle != PARAM_INVALID) {
+					param_get(parm_handle, &trim_val);
 					(void)io_reg_set(PX4IO_PAGE_SETUP, PX4IO_P_SETUP_TRIM_PITCH, FLOAT_TO_REG(trim_val));
 				}
 
-				trim_parm = param_find("TRIM_YAW");
-				if (trim_parm != PARAM_INVALID) {
-					param_get(trim_parm, &trim_val);
+				parm_handle = param_find("TRIM_YAW");
+				if (parm_handle != PARAM_INVALID) {
+					param_get(parm_handle, &trim_val);
 					(void)io_reg_set(PX4IO_PAGE_SETUP, PX4IO_P_SETUP_TRIM_YAW, FLOAT_TO_REG(trim_val));
 				}
+
+				/* S.BUS output */
+				int sbus_mode;
+				parm_handle = param_find("PWM_SBUS_MODE");
+				if (parm_handle != PARAM_INVALID) {
+					param_get(parm_handle, &sbus_mode);
+					if (sbus_mode == 1) {
+						/* enable S.BUS 1 */
+						(void)io_reg_modify(PX4IO_PAGE_SETUP, PX4IO_P_SETUP_FEATURES, 0, PX4IO_P_SETUP_FEATURES_SBUS1_OUT);
+					} else if (sbus_mode == 2) {
+						/* enable S.BUS 2 */
+						(void)io_reg_modify(PX4IO_PAGE_SETUP, PX4IO_P_SETUP_FEATURES, 0, PX4IO_P_SETUP_FEATURES_SBUS2_OUT);
+					} else {
+						/* disable S.BUS */
+						(void)io_reg_modify(PX4IO_PAGE_SETUP, PX4IO_P_SETUP_FEATURES, (PX4IO_P_SETUP_FEATURES_SBUS1_OUT | PX4IO_P_SETUP_FEATURES_SBUS2_OUT), 0);
+					}
+				}
 			}
 
 		}
diff --git a/src/drivers/px4io/px4io_params.c b/src/drivers/px4io/px4io_params.c
index 057bcaf150..51d39e97ba 100644
--- a/src/drivers/px4io/px4io_params.c
+++ b/src/drivers/px4io/px4io_params.c
@@ -129,3 +129,14 @@ PARAM_DEFINE_INT32(PWM_MAIN_REV7, 0);
  * @group PWM Outputs
  */
 PARAM_DEFINE_INT32(PWM_MAIN_REV8, 0);
+
+/**
+ * Enable S.BUS out
+ *
+ * Set to 1 to enable S.BUS version 1 output instead of RSSI.
+ *
+ * @min 0
+ * @max 1
+ * @group PWM Outputs
+ */
+PARAM_DEFINE_INT32(PWM_SBUS_MODE, 0);
diff --git a/src/modules/attitude_estimator_q/attitude_estimator_q_main.cpp b/src/modules/attitude_estimator_q/attitude_estimator_q_main.cpp
index e91d69051e..138a8c7e5c 100644
--- a/src/modules/attitude_estimator_q/attitude_estimator_q_main.cpp
+++ b/src/modules/attitude_estimator_q/attitude_estimator_q_main.cpp
@@ -203,7 +203,7 @@ int AttitudeEstimatorQ::start() {
 	_control_task = px4_task_spawn_cmd("attitude_estimator_q",
 				       SCHED_DEFAULT,
 				       SCHED_PRIORITY_MAX - 5,
-				       2500,
+				       2000,
 				       (px4_main_t)&AttitudeEstimatorQ::task_main_trampoline,
 				       nullptr);
 
diff --git a/src/modules/commander/commander.cpp b/src/modules/commander/commander.cpp
index 478bb85b73..38939b2b83 100644
--- a/src/modules/commander/commander.cpp
+++ b/src/modules/commander/commander.cpp
@@ -281,7 +281,7 @@ int commander_main(int argc, char *argv[])
 	if (!strcmp(argv[1], "start")) {
 
 		if (thread_running) {
-			warnx("commander already running");
+			warnx("already running");
 			/* this is not an error */
 			return 0;
 		}
@@ -294,11 +294,18 @@ int commander_main(int argc, char *argv[])
 					     commander_thread_main,
 					     (argv) ? (char * const *)&argv[2] : (char * const *)NULL);
 
-		while (!thread_running) {
-			usleep(200);
+		unsigned constexpr max_wait_us = 1000000;
+		unsigned constexpr max_wait_steps = 2000;
+
+		unsigned i;
+		for (i = 0; i < max_wait_steps; i++) {
+			usleep(max_wait_us / max_wait_steps);
+			if (thread_running) {
+				break;
+			}
 		}
 
-		return 0;
+		return !(i < max_wait_steps);
 	}
 
 	if (!strcmp(argv[1], "stop")) {
diff --git a/src/modules/mavlink/mavlink_main.cpp b/src/modules/mavlink/mavlink_main.cpp
index 0e9c7b8eb3..298f44d767 100644
--- a/src/modules/mavlink/mavlink_main.cpp
+++ b/src/modules/mavlink/mavlink_main.cpp
@@ -1960,6 +1960,12 @@ Mavlink::start(int argc, char *argv[])
 	// before returning to the shell
 	int ic = Mavlink::instance_count();
 
+	if (ic == MAVLINK_COMM_NUM_BUFFERS) {
+		warnx("Maximum MAVLink instance count of %d reached.",
+			(int)MAVLINK_COMM_NUM_BUFFERS);
+		return 1;
+	}
+
 	// Instantiate thread
 	char buf[24];
 	sprintf(buf, "mavlink_if%d", ic);
diff --git a/src/modules/mavlink/module.mk b/src/modules/mavlink/module.mk
index 7b2905f6b7..f197ebb7c9 100644
--- a/src/modules/mavlink/module.mk
+++ b/src/modules/mavlink/module.mk
@@ -54,6 +54,6 @@ MAXOPTIMIZATION	 = -Os
 
 MODULE_STACKSIZE = 1200
 
-EXTRACXXFLAGS	= -Weffc++ -Wno-attributes -Wno-packed
+EXTRACXXFLAGS	= -Weffc++ -Wno-attributes -Wno-packed -DMAVLINK_COMM_NUM_BUFFERS=3
 
-EXTRACFLAGS	= -Wno-packed
+EXTRACFLAGS	= -Wno-packed -DMAVLINK_COMM_NUM_BUFFERS=3
diff --git a/src/modules/sdlog2/sdlog2.c b/src/modules/sdlog2/sdlog2.c
index 10a07323c6..db7a5ee364 100644
--- a/src/modules/sdlog2/sdlog2.c
+++ b/src/modules/sdlog2/sdlog2.c
@@ -346,7 +346,20 @@ int sdlog2_main(int argc, char *argv[])
 						 3000,
 						 sdlog2_thread_main,
 						 (char * const *)argv);
-		return 0;
+
+		/* wait for the task to launch */
+		unsigned const max_wait_us = 1000000;
+		unsigned const max_wait_steps = 2000;
+
+		unsigned i;
+		for (i = 0; i < max_wait_steps; i++) {
+			usleep(max_wait_us / max_wait_steps);
+			if (thread_running) {
+				break;
+			}
+		}
+
+		return !(i < max_wait_steps);
 	}
 
 	if (!strcmp(argv[1], "stop")) {
@@ -1236,8 +1249,6 @@ int sdlog2_thread_main(int argc, char *argv[])
 	/* close stdout */
 	close(1);
 
-	thread_running = true;
-
 	/* initialize thread synchronization */
 	pthread_mutex_init(&logbuffer_mutex, NULL);
 	pthread_cond_init(&logbuffer_cond, NULL);
@@ -1271,6 +1282,9 @@ int sdlog2_thread_main(int argc, char *argv[])
 		sdlog2_start_log();
 	}
 
+	/* running, report */
+	thread_running = true;
+
 	while (!main_thread_should_exit) {
 		usleep(sleep_delay);
 
diff --git a/src/modules/systemlib/cpuload.c b/src/modules/systemlib/cpuload.c
index fe08da71fd..77743bdd8c 100644
--- a/src/modules/systemlib/cpuload.c
+++ b/src/modules/systemlib/cpuload.c
@@ -80,8 +80,6 @@ void cpuload_initialize_once()
 		system_load.tasks[i].valid = false;
 	}
 
-	uint64_t now = hrt_absolute_time();
-
 	int static_tasks_count = 2;	// there are at least 2 threads that should be initialized statically - "idle" and "init"
 
 #ifdef CONFIG_PAGING
@@ -96,7 +94,6 @@ void cpuload_initialize_once()
 
 	// perform static initialization of "system" threads
 	for (system_load.total_count = 0; system_load.total_count < static_tasks_count; system_load.total_count++) {
-		system_load.tasks[system_load.total_count].start_time = now;
 		system_load.tasks[system_load.total_count].total_runtime = 0;
 		system_load.tasks[system_load.total_count].curr_start_time = 0;
 		system_load.tasks[system_load.total_count].tcb = sched_gettcb(
@@ -113,7 +110,6 @@ void sched_note_start(FAR struct tcb_s *tcb)
 	for (i = 1; i < CONFIG_MAX_TASKS; i++) {
 		if (!system_load.tasks[i].valid) {
 			/* slot is available */
-			system_load.tasks[i].start_time = hrt_absolute_time();
 			system_load.tasks[i].total_runtime = 0;
 			system_load.tasks[i].curr_start_time = 0;
 			system_load.tasks[i].tcb = tcb;
diff --git a/src/modules/systemlib/cpuload.h b/src/modules/systemlib/cpuload.h
index dc173baa79..e997bb3d9a 100644
--- a/src/modules/systemlib/cpuload.h
+++ b/src/modules/systemlib/cpuload.h
@@ -42,7 +42,6 @@ __BEGIN_DECLS
 struct system_load_taskinfo_s {
 	uint64_t total_runtime;			///< Runtime since start (start_time - total_runtime)/(start_time - current_time) = load
 	uint64_t curr_start_time;		///< Start time of the current scheduling slot
-	uint64_t start_time;			///< FIRST start time of task
 #ifdef __PX4_NUTTX
 	FAR struct tcb_s *tcb;			///<
 #endif