diff --git a/cmake/nuttx/px4_impl_nuttx.cmake b/cmake/nuttx/px4_impl_nuttx.cmake
index 35b6c0b8bf..b9112a4c94 100644
--- a/cmake/nuttx/px4_impl_nuttx.cmake
+++ b/cmake/nuttx/px4_impl_nuttx.cmake
@@ -213,11 +213,11 @@ function(px4_nuttx_add_export)
 	endif()
 
 	# copy and export
+	file(RELATIVE_PATH nuttx_cp_src ${CMAKE_BINARY_DIR} ${CMAKE_SOURCE_DIR}/NuttX)
 	file(GLOB_RECURSE config_files ${CMAKE_SOURCE_DIR}/nuttx-configs/${CONFIG}/*)
 	add_custom_command(OUTPUT ${CMAKE_BINARY_DIR}/${CONFIG}.export
 		COMMAND ${MKDIR} -p ${nuttx_src}
-		COMMAND ${CP} -a ${CMAKE_SOURCE_DIR}/NuttX/. ${nuttx_src}/
-		COMMAND ${RM} -rf ${nuttx_src}/.git
+		COMMAND rsync -a --delete --exclude=.git ${nuttx_cp_src}/ ${CONFIG}/NuttX/
 		#COMMAND ${ECHO} Configuring NuttX for ${CONFIG}
 		COMMAND ${MAKE} --no-print-directory -C${nuttx_src}/nuttx -r --quiet distclean
 		COMMAND ${CP} -r ${CMAKE_SOURCE_DIR}/nuttx-configs/PX4_Warnings.mk ${nuttx_src}/nuttx/
@@ -227,6 +227,7 @@ function(px4_nuttx_add_export)
 		COMMAND ${MAKE} --no-print-directory --quiet -C ${nuttx_src}/nuttx -j${THREADS} -r CONFIG_ARCH_BOARD=${CONFIG} export > nuttx_build.log
 		COMMAND ${CP} -r ${nuttx_src}/nuttx/nuttx-export.zip ${CMAKE_BINARY_DIR}/${CONFIG}.export
 		DEPENDS ${config_files} ${DEPENDS}
+		WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
 		COMMENT "Building NuttX for ${CONFIG}")
 
 	# extract
@@ -438,16 +439,6 @@ function(px4_os_add_flags)
 
 	set(added_exe_linker_flags) # none currently
 
-	set(instrument_flags)
-	if ("${config_nuttx_hw_stack_check_${BOARD}}" STREQUAL "y")
-		set(instrument_flags
-			-finstrument-functions
-			-ffixed-r10
-			)
-		list(APPEND c_flags ${instrument_flags})
-		list(APPEND cxx_flags ${instrument_flags})
-	endif()
-
 	set(cpu_flags)
 	if (${BOARD} STREQUAL "px4fmu-v1")
 		set(cpu_flags