diff --git a/src/drivers/auterion_autostarter/AuterionAutostarter.cpp b/src/drivers/auterion_autostarter/AuterionAutostarter.cpp
index 7b22949891..6f4da6a510 100644
--- a/src/drivers/auterion_autostarter/AuterionAutostarter.cpp
+++ b/src/drivers/auterion_autostarter/AuterionAutostarter.cpp
@@ -393,7 +393,7 @@ int AuterionAutostarter::start(const char *start_command, const char **start_arg
 	int status = PX4_ERROR;
 
 	if (start_command != nullptr) {
-		int pid = exec_builtin(start_command, (char **)start_argv, NULL, 0);
+		int pid = exec_builtin(start_command, (char **)start_argv, NULL);
 
 		if (pid != -1) {
 			waitpid(pid, &status, WUNTRACED);
diff --git a/src/drivers/cdcacm_autostart/cdcacm_autostart.cpp b/src/drivers/cdcacm_autostart/cdcacm_autostart.cpp
index 2dc77aae42..86c1fd3d41 100644
--- a/src/drivers/cdcacm_autostart/cdcacm_autostart.cpp
+++ b/src/drivers/cdcacm_autostart/cdcacm_autostart.cpp
@@ -166,7 +166,7 @@ void CdcAcmAutostart::state_connected()
 		sched_lock();
 		static const char app[] {"mavlink"};
 		static const char *stop_argv[] {"mavlink", "stop", "-d", USB_DEVICE_PATH, NULL};
-		exec_builtin(app, (char **)stop_argv, NULL, 0);
+		exec_builtin(app, (char **)stop_argv, NULL);
 		sched_unlock();
 		_state = UsbAutoStartState::disconnecting;
 	}
@@ -546,7 +546,7 @@ int CdcAcmAutostart::execute_process(char **argv)
 	int pid = -1;
 	sched_lock();
 
-	pid = exec_builtin(argv[0], argv, nullptr, 0);
+	pid = exec_builtin(argv[0], argv, nullptr);
 
 	sched_unlock();
 	return pid;
diff --git a/src/drivers/cyphal/CanardSocketCAN.hpp b/src/drivers/cyphal/CanardSocketCAN.hpp
index ba93b48dbe..f397e3f713 100644
--- a/src/drivers/cyphal/CanardSocketCAN.hpp
+++ b/src/drivers/cyphal/CanardSocketCAN.hpp
@@ -44,7 +44,6 @@
 #include <sys/socket.h>
 
 #include <nuttx/can.h>
-#include <netpacket/can.h>
 
 #include <canard.h>
 
diff --git a/src/drivers/cyphal/NodeClient.cpp b/src/drivers/cyphal/NodeClient.cpp
index 0f2ae41076..88eda62fbc 100644
--- a/src/drivers/cyphal/NodeClient.cpp
+++ b/src/drivers/cyphal/NodeClient.cpp
@@ -41,7 +41,7 @@
 
 #define PNP_UNIQUE_ID_SIZE 16 // 128 bit unique id
 
-#include <crc64.h>
+#include <nuttx/crc64.h>
 #include "NodeClient.hpp"
 
 void NodeClient::callback(const CanardRxTransfer &receive)
diff --git a/src/drivers/px4io/px4io.cpp b/src/drivers/px4io/px4io.cpp
index 671651ed60..376ca5715c 100644
--- a/src/drivers/px4io/px4io.cpp
+++ b/src/drivers/px4io/px4io.cpp
@@ -45,7 +45,7 @@
 #include <px4_platform_common/px4_work_queue/ScheduledWorkItem.hpp>
 #include <px4_platform_common/sem.hpp>
 
-#include <crc32.h>
+#include <nuttx/crc32.h>
 
 #include <drivers/device/device.h>
 #include <drivers/drv_hrt.h>
diff --git a/src/drivers/px4io/px4io_uploader.cpp b/src/drivers/px4io/px4io_uploader.cpp
index 62c699afdd..abafa7bbfc 100644
--- a/src/drivers/px4io/px4io_uploader.cpp
+++ b/src/drivers/px4io/px4io_uploader.cpp
@@ -55,7 +55,7 @@
 #include <sys/stat.h>
 #include <nuttx/arch.h>
 
-#include <crc32.h>
+#include <nuttx/crc32.h>
 
 #include "uploader.h"
 
diff --git a/src/drivers/tap_esc/tap_esc_uploader.cpp b/src/drivers/tap_esc/tap_esc_uploader.cpp
index 350e366b73..cf0f89a5df 100644
--- a/src/drivers/tap_esc/tap_esc_uploader.cpp
+++ b/src/drivers/tap_esc/tap_esc_uploader.cpp
@@ -58,7 +58,7 @@
 #include <termios.h>
 #include <sys/stat.h>
 #include <nuttx/arch.h>
-#include <crc32.h>
+#include <nuttx/crc32.h>
 #include <drivers/drv_hrt.h>
 #include <sys/ioctl.h>
 
diff --git a/src/drivers/uavcan/CMakeLists.txt b/src/drivers/uavcan/CMakeLists.txt
index 70512233cf..f25fa24206 100644
--- a/src/drivers/uavcan/CMakeLists.txt
+++ b/src/drivers/uavcan/CMakeLists.txt
@@ -71,6 +71,12 @@ if(NOT config_uavcan_num_ifaces)
 	message(FATAL_ERROR "config_uavcan_num_ifaces not set")
 endif()
 
+if(CONFIG_LIB_TFLM)
+	set(UAVCAN_IMPLEMENT_PLACEMENT_NEW 0)
+else()
+	set(UAVCAN_IMPLEMENT_PLACEMENT_NEW 1)
+endif()
+
 string(TOUPPER "${PX4_PLATFORM}" OS_UPPER)
 string(TOUPPER "${UAVCAN_DRIVER}" UAVCAN_DRIVER_UPPER)
 add_definitions(
@@ -80,7 +86,7 @@ add_definitions(
 	-DUAVCAN_NUM_IFACES=${config_uavcan_num_ifaces}
 	-DUAVCAN_CPP_VERSION=UAVCAN_CPP03
 	-DUAVCAN_DRIVER=uavcan_${UAVCAN_DRIVER}
-	-DUAVCAN_IMPLEMENT_PLACEMENT_NEW=1
+	-DUAVCAN_IMPLEMENT_PLACEMENT_NEW=${UAVCAN_IMPLEMENT_PLACEMENT_NEW}
 	-DUAVCAN_MEM_POOL_BLOCK_SIZE=48
 	-DUAVCAN_NO_ASSERTIONS
 	-DUAVCAN_PLATFORM=${UAVCAN_PLATFORM}
diff --git a/src/drivers/uavcan/uavcan_drivers/kinetis/driver/src/uc_kinetis_thread.cpp b/src/drivers/uavcan/uavcan_drivers/kinetis/driver/src/uc_kinetis_thread.cpp
index a64826801c..894f89c674 100644
--- a/src/drivers/uavcan/uavcan_drivers/kinetis/driver/src/uc_kinetis_thread.cpp
+++ b/src/drivers/uavcan/uavcan_drivers/kinetis/driver/src/uc_kinetis_thread.cpp
@@ -51,7 +51,9 @@ bool BusEvent::wait(uavcan::MonotonicDuration duration)
 
 void BusEvent::signalFromInterrupt()
 {
-	if (sem_.semcount <= 0) {
+	int semcount;
+
+	if (sem_getvalue(&sem_, &semcount) == 0 && semcount <= 0) {
 		(void)sem_post(&sem_);
 	}
 
diff --git a/src/drivers/uavcan/uavcan_drivers/socketcan/driver/include/uavcan_nuttx/socketcan.hpp b/src/drivers/uavcan/uavcan_drivers/socketcan/driver/include/uavcan_nuttx/socketcan.hpp
index 12fc861400..2d212f7f32 100644
--- a/src/drivers/uavcan/uavcan_drivers/socketcan/driver/include/uavcan_nuttx/socketcan.hpp
+++ b/src/drivers/uavcan/uavcan_drivers/socketcan/driver/include/uavcan_nuttx/socketcan.hpp
@@ -42,7 +42,6 @@
 #include <sys/socket.h>
 
 #include <nuttx/can.h>
-#include <netpacket/can.h>
 
 namespace uavcan_socketcan
 {
diff --git a/src/drivers/uavcan/uavcan_drivers/socketcan/driver/src/socketcan.cpp b/src/drivers/uavcan/uavcan_drivers/socketcan/driver/src/socketcan.cpp
index 8df5c21b5e..efea7c7a69 100644
--- a/src/drivers/uavcan/uavcan_drivers/socketcan/driver/src/socketcan.cpp
+++ b/src/drivers/uavcan/uavcan_drivers/socketcan/driver/src/socketcan.cpp
@@ -49,7 +49,6 @@
 #include <string.h>
 
 #include <nuttx/can.h>
-#include <netpacket/can.h>
 
 #define MODULE_NAME "UAVCAN_SOCKETCAN"
 
diff --git a/src/drivers/uavcan/uavcan_drivers/socketcan/driver/src/thread.cpp b/src/drivers/uavcan/uavcan_drivers/socketcan/driver/src/thread.cpp
index 1060c611f2..8ae56867c5 100644
--- a/src/drivers/uavcan/uavcan_drivers/socketcan/driver/src/thread.cpp
+++ b/src/drivers/uavcan/uavcan_drivers/socketcan/driver/src/thread.cpp
@@ -79,7 +79,9 @@ bool BusEvent::wait(uavcan::MonotonicDuration duration)
 
 void BusEvent::signalFromInterrupt()
 {
-	if (sem_.semcount <= 0) {
+	int semcount;
+
+	if (sem_getvalue(&sem_, &semcount) == 0 && semcount <= 0) {
 		(void)sem_post(&sem_);
 	}
 
diff --git a/src/drivers/uavcan/uavcan_drivers/stm32/driver/src/uc_stm32_thread.cpp b/src/drivers/uavcan/uavcan_drivers/stm32/driver/src/uc_stm32_thread.cpp
index 7e1f21bc6e..8cb70afc0f 100644
--- a/src/drivers/uavcan/uavcan_drivers/stm32/driver/src/uc_stm32_thread.cpp
+++ b/src/drivers/uavcan/uavcan_drivers/stm32/driver/src/uc_stm32_thread.cpp
@@ -53,7 +53,9 @@ bool BusEvent::wait(uavcan::MonotonicDuration duration)
 
 void BusEvent::signalFromInterrupt()
 {
-	if (sem_.semcount <= 0) {
+	int semcount;
+
+	if (sem_getvalue(&sem_, &semcount) == 0 && semcount <= 0) {
 		(void)sem_post(&sem_);
 	}
 
diff --git a/src/drivers/uavcan/uavcan_drivers/stm32h7/driver/src/uc_stm32h7_thread.cpp b/src/drivers/uavcan/uavcan_drivers/stm32h7/driver/src/uc_stm32h7_thread.cpp
index 9af0a40a53..6c4fb2b4dd 100644
--- a/src/drivers/uavcan/uavcan_drivers/stm32h7/driver/src/uc_stm32h7_thread.cpp
+++ b/src/drivers/uavcan/uavcan_drivers/stm32h7/driver/src/uc_stm32h7_thread.cpp
@@ -53,7 +53,9 @@ bool BusEvent::wait(uavcan::MonotonicDuration duration)
 
 void BusEvent::signalFromInterrupt()
 {
-	if (sem_.semcount <= 0) {
+	int semcount;
+
+	if (sem_getvalue(&sem_, &semcount) == 0 && semcount <= 0) {
 		(void)sem_post(&sem_);
 	}
 
diff --git a/src/lib/cdev/CDev.cpp b/src/lib/cdev/CDev.cpp
index b5bcce2dd3..f7c0cfdbcc 100644
--- a/src/lib/cdev/CDev.cpp
+++ b/src/lib/cdev/CDev.cpp
@@ -287,11 +287,21 @@ CDev::poll(file_t *filep, px4_pollfd_struct_t *fds, bool setup)
 			 */
 			fds->revents |= fds->events & poll_state(filep);
 
-			/* yes? post the notification */
+			/* yes? invoke the callback */
+#ifdef __PX4_NUTTX
+
+			if (fds->revents != 0 && fds->cb != nullptr) {
+				fds->cb(fds);
+			}
+
+#else
+
 			if (fds->revents != 0) {
 				px4_sem_post(fds->sem);
 			}
 
+#endif
+
 		}
 
 		ATOMIC_LEAVE;
@@ -335,9 +345,19 @@ CDev::poll_notify_one(px4_pollfd_struct_t *fds, px4_pollevent_t events)
 
 	PX4_DEBUG(" Events fds=%p %0x %0x %0x", fds, fds->revents, fds->events, events);
 
+#ifdef __PX4_NUTTX
+
+	if (fds->revents != 0 && fds->cb != nullptr) {
+		fds->cb(fds);
+	}
+
+#else
+
 	if (fds->revents != 0) {
 		px4_sem_post(fds->sem);
 	}
+
+#endif
 }
 
 int
diff --git a/src/lib/cdev/nuttx/cdev_platform.cpp b/src/lib/cdev/nuttx/cdev_platform.cpp
index 39de49a55c..9116c1ee63 100644
--- a/src/lib/cdev/nuttx/cdev_platform.cpp
+++ b/src/lib/cdev/nuttx/cdev_platform.cpp
@@ -87,10 +87,6 @@ unlink	: nullptr
 static int
 cdev_open(file_t *filp)
 {
-	if ((filp->f_inode->i_flags & FSNODEFLAG_DELETED) != 0) {
-		return -ENODEV;
-	}
-
 	cdev::CDev *cdev = (cdev::CDev *)(filp->f_inode->i_private);
 
 	return cdev->open(filp);
@@ -99,7 +95,7 @@ cdev_open(file_t *filp)
 static int
 cdev_close(file_t *filp)
 {
-	if ((filp->f_inode->i_flags & FSNODEFLAG_DELETED) != 0) {
+	if ((filp->f_inode->i_crefs) == 0) {
 		return -ENODEV;
 	}
 
@@ -111,7 +107,7 @@ cdev_close(file_t *filp)
 static ssize_t
 cdev_read(file_t *filp, char *buffer, size_t buflen)
 {
-	if ((filp->f_inode->i_flags & FSNODEFLAG_DELETED) != 0) {
+	if ((filp->f_inode->i_crefs) == 0) {
 		return -ENODEV;
 	}
 
@@ -123,7 +119,7 @@ cdev_read(file_t *filp, char *buffer, size_t buflen)
 static ssize_t
 cdev_write(file_t *filp, const char *buffer, size_t buflen)
 {
-	if ((filp->f_inode->i_flags & FSNODEFLAG_DELETED) != 0) {
+	if ((filp->f_inode->i_crefs) == 0) {
 		return -ENODEV;
 	}
 
@@ -135,7 +131,7 @@ cdev_write(file_t *filp, const char *buffer, size_t buflen)
 static off_t
 cdev_seek(file_t *filp, off_t offset, int whence)
 {
-	if ((filp->f_inode->i_flags & FSNODEFLAG_DELETED) != 0) {
+	if ((filp->f_inode->i_crefs) == 0) {
 		return -ENODEV;
 	}
 
@@ -147,7 +143,7 @@ cdev_seek(file_t *filp, off_t offset, int whence)
 static int
 cdev_ioctl(file_t *filp, int cmd, unsigned long arg)
 {
-	if ((filp->f_inode->i_flags & FSNODEFLAG_DELETED) != 0) {
+	if ((filp->f_inode->i_crefs) == 0) {
 		return -ENODEV;
 	}
 
@@ -159,7 +155,7 @@ cdev_ioctl(file_t *filp, int cmd, unsigned long arg)
 static int
 cdev_poll(file_t *filp, px4_pollfd_struct_t *fds, bool setup)
 {
-	if ((filp->f_inode->i_flags & FSNODEFLAG_DELETED) != 0) {
+	if ((filp->f_inode->i_crefs) == 0) {
 		return -ENODEV;
 	}
 
diff --git a/src/lib/parameters/flashparams/flashfs.c b/src/lib/parameters/flashparams/flashfs.c
index 97847fa1a9..e9c2c4d363 100644
--- a/src/lib/parameters/flashparams/flashfs.c
+++ b/src/lib/parameters/flashparams/flashfs.c
@@ -44,7 +44,7 @@
 
 #include <px4_platform_common/defines.h>
 #include <px4_platform_common/posix.h>
-#include <crc32.h>
+#include <nuttx/crc32.h>
 #include <stddef.h>
 #include <string.h>
 #include <stdbool.h>
diff --git a/src/lib/parameters/flashparams/flashfs32.c b/src/lib/parameters/flashparams/flashfs32.c
index 25e97d2563..8d3e703bc0 100644
--- a/src/lib/parameters/flashparams/flashfs32.c
+++ b/src/lib/parameters/flashparams/flashfs32.c
@@ -48,7 +48,7 @@
 
 #include <px4_platform_common/defines.h>
 #include <px4_platform_common/posix.h>
-#include <crc32.h>
+#include <nuttx/crc32.h>
 #include <stddef.h>
 #include <string.h>
 #include <stdbool.h>
diff --git a/src/lib/parameters/parameters.cpp b/src/lib/parameters/parameters.cpp
index 772a5c2a9e..c08bca2984 100644
--- a/src/lib/parameters/parameters.cpp
+++ b/src/lib/parameters/parameters.cpp
@@ -47,7 +47,11 @@
 #include <parameters/px4_parameters.hpp>
 #include <lib/tinybson/tinybson.h>
 
+#if defined(__PX4_NUTTX)
+#include <nuttx/crc32.h>
+#else
 #include <crc32.h>
+#endif
 #include <float.h>
 #include <math.h>
 
diff --git a/src/lib/systemlib/hardfault_log.h b/src/lib/systemlib/hardfault_log.h
index 678a0398f3..0379c93668 100644
--- a/src/lib/systemlib/hardfault_log.h
+++ b/src/lib/systemlib/hardfault_log.h
@@ -258,7 +258,7 @@ typedef struct {
 	_stack_s interrupt;
 #endif
 
-} stack_t;
+} px4_stack_t;
 
 /* Not Used for reference only */
 
@@ -371,7 +371,7 @@ typedef struct {
 	int                   pid;                    /* Process ID */
 	uint32_t              regs[XCPTCONTEXT_REGS]; /* Interrupt register save area */
 	fault_regs_s          fault_regs;             /* NVIC status */
-	stack_t               stacks;                 /* Stack info */
+	px4_stack_t           stacks;                 /* Stack info */
 #if CONFIG_TASK_NAME_SIZE > 0
 	char                  name[CONFIG_TASK_NAME_SIZE + 1]; /* Task name (with NULL
 													* terminator) */
diff --git a/src/modules/mavlink/mavlink_ftp.cpp b/src/modules/mavlink/mavlink_ftp.cpp
index 142c7302dc..be13d27a9e 100644
--- a/src/modules/mavlink/mavlink_ftp.cpp
+++ b/src/modules/mavlink/mavlink_ftp.cpp
@@ -34,7 +34,11 @@
 /// @file mavlink_ftp.cpp
 ///	@author px4dev, Don Gagne <don@thegagnes.com>
 
+#if defined(__PX4_NUTTX)
+#include <nuttx/crc32.h>
+#else
 #include <crc32.h>
+#endif
 #include <unistd.h>
 #include <stdio.h>
 #include <fcntl.h>
diff --git a/src/modules/mavlink/mavlink_ftp.h b/src/modules/mavlink/mavlink_ftp.h
index 344a61997f..506ff6dcd7 100644
--- a/src/modules/mavlink/mavlink_ftp.h
+++ b/src/modules/mavlink/mavlink_ftp.h
@@ -37,7 +37,7 @@
 ///     @author px4dev, Don Gagne <don@thegagnes.com>
 
 #include <dirent.h>
-#include <queue.h>
+#include <sys/queue.h>
 
 #include <px4_platform_common/defines.h>
 #include <systemlib/err.h>
diff --git a/src/modules/mavlink/mavlink_mission.cpp b/src/modules/mavlink/mavlink_mission.cpp
index b773641177..4f4a08d992 100644
--- a/src/modules/mavlink/mavlink_mission.cpp
+++ b/src/modules/mavlink/mavlink_mission.cpp
@@ -53,7 +53,11 @@
 #include <navigator/navigation.h>
 #include <uORB/topics/mission.h>
 #include <uORB/topics/mission_result.h>
+#if defined(__PX4_NUTTX)
+#include <nuttx/crc32.h>
+#else
 #include <crc32.h>
+#endif
 
 using matrix::wrap_2pi;
 
diff --git a/src/modules/navigator/geofence.cpp b/src/modules/navigator/geofence.cpp
index 9d29586bcf..6283929a01 100644
--- a/src/modules/navigator/geofence.cpp
+++ b/src/modules/navigator/geofence.cpp
@@ -43,7 +43,11 @@
 #include "navigation.h"
 
 #include <ctype.h>
+#if defined(__PX4_NUTTX)
+#include <nuttx/crc32.h>
+#else
 #include <crc32.h>
+#endif
 
 #include <dataman_client/DatamanClient.hpp>
 #include <drivers/drv_hrt.h>
diff --git a/src/modules/px4iofirmware/px4io.cpp b/src/modules/px4iofirmware/px4io.cpp
index 176d6bd1eb..3b2aa6b07d 100644
--- a/src/modules/px4iofirmware/px4io.cpp
+++ b/src/modules/px4iofirmware/px4io.cpp
@@ -48,7 +48,7 @@
 #include <malloc.h>
 #include <poll.h>
 #include <signal.h>
-#include <crc32.h>
+#include <nuttx/crc32.h>
 #include <syslog.h>
 
 #include <drivers/drv_pwm_output.h>
diff --git a/src/modules/uxrce_dds_client/CMakeLists.txt b/src/modules/uxrce_dds_client/CMakeLists.txt
index fba4ca45cf..8947d3bdb4 100644
--- a/src/modules/uxrce_dds_client/CMakeLists.txt
+++ b/src/modules/uxrce_dds_client/CMakeLists.txt
@@ -62,6 +62,10 @@ else()
 		set(lib_dir "lib")
 	endif()
 
+	if(PX4_PLATFORM STREQUAL "nuttx")
+		set(c_flags_with_includes "${c_flags_with_includes} -Wno-cast-align -D__PX4_NUTTX")
+	endif()
+
 	include(ExternalProject)
 	ExternalProject_Add(
 		libmicroxrceddsclient_project