diff --git a/cmake/common/px4_base.cmake b/cmake/common/px4_base.cmake
index 37233c0b81e..1617c0a4073 100644
--- a/cmake/common/px4_base.cmake
+++ b/cmake/common/px4_base.cmake
@@ -541,8 +541,9 @@ function(px4_add_common_flags)
 		-Wall
 		-Werror
 		-Wextra
+		-Wpacked
 		-Wno-sign-compare
-		#-Wshadow # very verbose due to eigen
+		-Wshadow
 		-Wfloat-equal
 		-Wpointer-arith
 		-Wmissing-declarations
diff --git a/src/drivers/camera_trigger/camera_trigger.cpp b/src/drivers/camera_trigger/camera_trigger.cpp
index f4163ca5eec..5c144b45c88 100644
--- a/src/drivers/camera_trigger/camera_trigger.cpp
+++ b/src/drivers/camera_trigger/camera_trigger.cpp
@@ -116,7 +116,7 @@ private:
 	int 			_gpio_fd;
 
 	int 			_polarity;
-	int			_mode;
+	int				_mode;
 	float 			_activation_time;
 	float  			_interval;
 	float  			_distance;
@@ -229,9 +229,9 @@ CameraTrigger::CameraTrigger() :
 		i++;
 	}
 
-	struct camera_trigger_s	trigger = {};
+	struct camera_trigger_s	camera_trigger = {};
 
-	_trigger_pub = orb_advertise(ORB_ID(camera_trigger), &trigger);
+	_trigger_pub = orb_advertise(ORB_ID(camera_trigger), &camera_trigger);
 }
 
 CameraTrigger::~CameraTrigger()
diff --git a/src/drivers/pwm_out_sim/pwm_out_sim.cpp b/src/drivers/pwm_out_sim/pwm_out_sim.cpp
index 96db5d0d073..457e85bb91c 100644
--- a/src/drivers/pwm_out_sim/pwm_out_sim.cpp
+++ b/src/drivers/pwm_out_sim/pwm_out_sim.cpp
@@ -383,8 +383,7 @@ PWMSim::task_main()
 	_armed_sub = orb_subscribe(ORB_ID(actuator_armed));
 
 	/* advertise the mixed control outputs */
-	actuator_outputs_s outputs;
-	memset(&outputs, 0, sizeof(outputs));
+	actuator_outputs_s outputs = {};
 
 	/* advertise the mixed control outputs, insist on the first group output */
 	_outputs_pub = orb_advertise(ORB_ID(actuator_outputs), &outputs);
@@ -483,7 +482,6 @@ PWMSim::task_main()
 			}
 
 			/* do mixing */
-			actuator_outputs_s outputs = {};
 			num_outputs = _mixers->mix(&outputs.output[0], num_outputs, NULL);
 			outputs.noutputs = num_outputs;
 			outputs.timestamp = hrt_absolute_time();
diff --git a/src/drivers/px4fmu/fmu.cpp b/src/drivers/px4fmu/fmu.cpp
index 893687f18f6..4c39f3b7c4a 100644
--- a/src/drivers/px4fmu/fmu.cpp
+++ b/src/drivers/px4fmu/fmu.cpp
@@ -861,17 +861,17 @@ PX4FMU::fill_rc_in(uint16_t raw_rc_count,
 
 		/* set RSSI if analog RSSI input is present */
 		if (_analog_rc_rssi_stable) {
-			float rssi = ((_analog_rc_rssi_volt - 0.2f) / 3.0f) * 100.0f;
+			float rssi_analog = ((_analog_rc_rssi_volt - 0.2f) / 3.0f) * 100.0f;
 
-			if (rssi > 100.0f) {
-				rssi = 100.0f;
+			if (rssi_analog > 100.0f) {
+				rssi_analog = 100.0f;
 			}
 
-			if (rssi < 0.0f) {
-				rssi = 0.0f;
+			if (rssi_analog < 0.0f) {
+				rssi_analog = 0.0f;
 			}
 
-			_rc_in.rssi = rssi;
+			_rc_in.rssi = rssi_analog;
 
 		} else {
 			_rc_in.rssi = 255;
diff --git a/src/drivers/snapdragon_rc_pwm/CMakeLists.txt b/src/drivers/snapdragon_rc_pwm/CMakeLists.txt
index 6fae0f31578..405b903306c 100644
--- a/src/drivers/snapdragon_rc_pwm/CMakeLists.txt
+++ b/src/drivers/snapdragon_rc_pwm/CMakeLists.txt
@@ -35,6 +35,8 @@ px4_add_module(
 	MAIN snapdragon_rc_pwm
 	COMPILE_FLAGS
 		-Os
+		-Wno-attributes
+		-Wno-packed
 	SRCS
 		snapdragon_rc_pwm.cpp
 	DEPENDS
diff --git a/src/modules/commander/CMakeLists.txt b/src/modules/commander/CMakeLists.txt
index 8972791a41a..be0d32dec7e 100644
--- a/src/modules/commander/CMakeLists.txt
+++ b/src/modules/commander/CMakeLists.txt
@@ -36,6 +36,8 @@ px4_add_module(
 	STACK_MAIN 4096
 	STACK_MAX 2450
 	COMPILE_FLAGS
+		-Wno-attributes
+		-Wno-packed
 		-Os
 	SRCS
 		commander.cpp
diff --git a/src/modules/commander/commander.cpp b/src/modules/commander/commander.cpp
index 701ed0561e6..a1d66d0cad9 100644
--- a/src/modules/commander/commander.cpp
+++ b/src/modules/commander/commander.cpp
@@ -1700,7 +1700,7 @@ int commander_thread_main(int argc, char *argv[])
 				    !armed.armed) {
 
 					bool chAirspeed = false;
-					bool hotplug_timeout = hrt_elapsed_time(&commander_boot_timestamp) > HOTPLUG_SENS_TIMEOUT;
+					hotplug_timeout = hrt_elapsed_time(&commander_boot_timestamp) > HOTPLUG_SENS_TIMEOUT;
 
 					/* Perform airspeed check only if circuit breaker is not
 					 * engaged and it's not a rotary wing
@@ -2874,7 +2874,7 @@ check_valid(hrt_abstime timestamp, hrt_abstime timeout, bool valid_in, bool *val
 }
 
 void
-control_status_leds(vehicle_status_s *status_local, const actuator_armed_s *actuator_armed, bool changed, battery_status_s *battery)
+control_status_leds(vehicle_status_s *status_local, const actuator_armed_s *actuator_armed, bool changed, battery_status_s *battery_status)
 {
 	/* driving rgbled */
 	if (changed) {
@@ -2907,9 +2907,9 @@ control_status_leds(vehicle_status_s *status_local, const actuator_armed_s *actu
 			/* set color */
 			if (status.failsafe) {
 				rgbled_set_color(RGBLED_COLOR_PURPLE);
-			} else if (battery->warning == battery_status_s::BATTERY_WARNING_LOW) {
+			} else if (battery_status->warning == battery_status_s::BATTERY_WARNING_LOW) {
 				rgbled_set_color(RGBLED_COLOR_AMBER);
-			} else if (battery->warning == battery_status_s::BATTERY_WARNING_CRITICAL) {
+			} else if (battery_status->warning == battery_status_s::BATTERY_WARNING_CRITICAL) {
 				rgbled_set_color(RGBLED_COLOR_RED);
 			} else {
 				if (status_flags.condition_home_position_valid && status_flags.condition_global_position_valid) {
diff --git a/src/modules/commander/mag_calibration.cpp b/src/modules/commander/mag_calibration.cpp
index 7139bbe056a..819da7aa286 100644
--- a/src/modules/commander/mag_calibration.cpp
+++ b/src/modules/commander/mag_calibration.cpp
@@ -81,7 +81,7 @@ int device_prio_max = 0;
 int32_t device_id_primary = 0;
 static unsigned _last_mag_progress = 0;
 
-calibrate_return mag_calibrate_all(orb_advert_t *mavlink_log_pub, int32_t (&device_ids)[max_mags]);
+calibrate_return mag_calibrate_all(orb_advert_t *mavlink_log_pub);
 
 /// Data passed to calibration worker routine
 typedef struct  {
@@ -117,7 +117,7 @@ int do_mag_calibration(orb_advert_t *mavlink_log_pub)
 
 	char str[30];
 
-	for (size_t i=0; i<max_mags; i++) {
+	for (size_t i=0; i < max_mags; i++) {
 		device_ids[i] = 0; // signals no mag
 	}
 
@@ -202,7 +202,7 @@ int do_mag_calibration(orb_advert_t *mavlink_log_pub)
 
 	// Calibrate all mags at the same time
 	if (result == OK) {
-		switch (mag_calibrate_all(mavlink_log_pub, device_ids)) {
+		switch (mag_calibrate_all(mavlink_log_pub)) {
 			case calibrate_return_cancelled:
 				// Cancel message already displayed, we're done here
 				result = ERROR;
@@ -435,7 +435,7 @@ static calibrate_return mag_calibration_worker(detect_orientation_return orienta
 	return result;
 }
 
-calibrate_return mag_calibrate_all(orb_advert_t *mavlink_log_pub, int32_t (&device_ids)[max_mags])
+calibrate_return mag_calibrate_all(orb_advert_t *mavlink_log_pub)
 {
 	calibrate_return result = calibrate_return_ok;
 
diff --git a/src/modules/mavlink/mavlink_parameters.cpp b/src/modules/mavlink/mavlink_parameters.cpp
index 3402be9839a..b24d0464fba 100644
--- a/src/modules/mavlink/mavlink_parameters.cpp
+++ b/src/modules/mavlink/mavlink_parameters.cpp
@@ -182,13 +182,13 @@ MavlinkParametersManager::handle_message(const mavlink_message_t *msg)
 						uint32_t hash = param_hash_check();
 
 						/* build the one-off response message */
-						mavlink_param_value_t msg;
-						msg.param_count = param_count_used();
-						msg.param_index = -1;
-						strncpy(msg.param_id, HASH_PARAM, MAVLINK_MSG_PARAM_VALUE_FIELD_PARAM_ID_LEN);
-						msg.param_type = MAV_PARAM_TYPE_UINT32;
-						memcpy(&msg.param_value, &hash, sizeof(hash));
-						_mavlink->send_message(MAVLINK_MSG_ID_PARAM_VALUE, &msg);
+						mavlink_param_value_t param_value;
+						param_value.param_count = param_count_used();
+						param_value.param_index = -1;
+						strncpy(param_value.param_id, HASH_PARAM, MAVLINK_MSG_PARAM_VALUE_FIELD_PARAM_ID_LEN);
+						param_value.param_type = MAV_PARAM_TYPE_UINT32;
+						memcpy(&param_value.param_value, &hash, sizeof(hash));
+						_mavlink->send_message(MAVLINK_MSG_ID_PARAM_VALUE, &param_value);
 					} else {
 						/* local name buffer to enforce null-terminated string */
 						char name[MAVLINK_MSG_PARAM_VALUE_FIELD_PARAM_ID_LEN + 1];
diff --git a/src/modules/uORB/uORBTest_UnitTest.cpp b/src/modules/uORB/uORBTest_UnitTest.cpp
index e3e416b6c8c..c91172c107d 100644
--- a/src/modules/uORB/uORBTest_UnitTest.cpp
+++ b/src/modules/uORB/uORBTest_UnitTest.cpp
@@ -181,14 +181,14 @@ int uORBTest::UnitTest::test_unadvertise()
 	}
 
 	//try to advertise and see whether we get the right instance
-	int instance[4];
+	int instance_test[4];
 	struct orb_test t;
 
 	for (int i = 0; i < 4; ++i) {
-		_pfd[i] = orb_advertise_multi(ORB_ID(orb_multitest), &t, &instance[i], ORB_PRIO_MAX);
+		_pfd[i] = orb_advertise_multi(ORB_ID(orb_multitest), &t, &instance_test[i], ORB_PRIO_MAX);
 
-		if (instance[i] != i) {
-			return test_fail("got wrong instance (should be %i, is %i)", i, instance[i]);
+		if (instance_test[i] != i) {
+			return test_fail("got wrong instance (should be %i, is %i)", i, instance_test[i]);
 		}
 	}
 
diff --git a/src/modules/uavcan/CMakeLists.txt b/src/modules/uavcan/CMakeLists.txt
index 72dac21b089..c485fc8da6b 100644
--- a/src/modules/uavcan/CMakeLists.txt
+++ b/src/modules/uavcan/CMakeLists.txt
@@ -59,6 +59,8 @@ px4_add_module(
 	STACK_MAIN 3200
 	STACK_MAX 1500
 	COMPILE_FLAGS
+		-Wno-attributes
+		-Wno-packed
 		-Wno-deprecated-declarations
 		-Os
 	SRCS
diff --git a/src/platforms/posix/drivers/accelsim/CMakeLists.txt b/src/platforms/posix/drivers/accelsim/CMakeLists.txt
index afa59e515f1..d4146b81291 100644
--- a/src/platforms/posix/drivers/accelsim/CMakeLists.txt
+++ b/src/platforms/posix/drivers/accelsim/CMakeLists.txt
@@ -33,6 +33,8 @@
 px4_add_module(
 	MODULE platforms__posix__drivers__accelsim
 	MAIN accelsim
+	COMPILE_FLAGS
+		-Wno-packed
 	SRCS
 		accelsim.cpp
 	DEPENDS
diff --git a/src/platforms/posix/drivers/airspeedsim/CMakeLists.txt b/src/platforms/posix/drivers/airspeedsim/CMakeLists.txt
index 8c2a410862d..cecefb204ee 100644
--- a/src/platforms/posix/drivers/airspeedsim/CMakeLists.txt
+++ b/src/platforms/posix/drivers/airspeedsim/CMakeLists.txt
@@ -34,6 +34,7 @@ px4_add_module(
 	MODULE platforms__posix__drivers__airspeedsim
 	MAIN measairspeedsim
 	COMPILE_FLAGS
+		-Wno-packed
 		-Os
 	SRCS
 		airspeedsim.cpp
diff --git a/src/platforms/posix/drivers/barosim/CMakeLists.txt b/src/platforms/posix/drivers/barosim/CMakeLists.txt
index 6e3a1052046..6103737bfb0 100644
--- a/src/platforms/posix/drivers/barosim/CMakeLists.txt
+++ b/src/platforms/posix/drivers/barosim/CMakeLists.txt
@@ -34,6 +34,7 @@ px4_add_module(
 	MODULE platforms__posix__drivers__barosim
 	MAIN barosim
 	COMPILE_FLAGS
+		-Wno-packed
 		-Os
 	SRCS
 		baro.cpp
diff --git a/src/platforms/posix/drivers/gpssim/CMakeLists.txt b/src/platforms/posix/drivers/gpssim/CMakeLists.txt
index 2c580d7757c..60cd2de7a8c 100644
--- a/src/platforms/posix/drivers/gpssim/CMakeLists.txt
+++ b/src/platforms/posix/drivers/gpssim/CMakeLists.txt
@@ -34,6 +34,7 @@ px4_add_module(
 	MODULE platforms__posix__drivers__gpssim
 	MAIN gpssim
 	COMPILE_FLAGS
+		-Wno-packed
 		-Os
 	SRCS
 		gpssim.cpp
diff --git a/src/platforms/posix/drivers/gyrosim/CMakeLists.txt b/src/platforms/posix/drivers/gyrosim/CMakeLists.txt
index bac977afbb5..88571e41b6f 100644
--- a/src/platforms/posix/drivers/gyrosim/CMakeLists.txt
+++ b/src/platforms/posix/drivers/gyrosim/CMakeLists.txt
@@ -35,6 +35,7 @@ px4_add_module(
 	MAIN gyrosim
 	STACK_MAIN 1200
 	COMPILE_FLAGS
+		-Wno-packed
 		-Os
 	SRCS
 		gyrosim.cpp