diff --git a/CMakeLists.txt b/CMakeLists.txt
index e547333c87..9f04b1fdd6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -126,6 +126,7 @@ file(GLOB_RECURSE configs RELATIVE cmake/configs "cmake/configs/*.cmake")
 set_property(CACHE CONFIG PROPERTY STRINGS ${configs})
 set(THREADS "4" CACHE STRING
 	"number of threads to use for external build processes")
+set(DEBUG_PORT "/dev/ttyACM0" CACHE STRING "debugging port")
 
 #=============================================================================
 # configuration
diff --git a/Makefile b/Makefile
index 4f60d249fb..b1dd099eb6 100644
--- a/Makefile
+++ b/Makefile
@@ -54,16 +54,22 @@
 # rest are arguments to pass to the makefile generated
 # by cmake in the subdirectory
 ARGS := $(wordlist 2,$(words $(MAKECMDGOALS)),$(MAKECMDGOALS))
-j ?= 1
+j ?= 4
 
 # Functions
 # --------------------------------------------------------------------
-# define a make function to describe how to build a cmake config
+# describe how to build a cmake config
 define cmake-build
 +mkdir -p $(PWD)/build_$@ && cd $(PWD)/build_$@ && cmake .. -DCONFIG=$(1)
-+make -C $(PWD)/build_$@ --no-print-directory $(ARGS)
++make -j$(j) -C $(PWD)/build_$@ --no-print-directory $(ARGS)
 endef
 
+# create empty targets to avoid msgs for targets passed to cmake
+define cmake-targ
+$(1):
+	@#
+.PHONY: $(1)
+endef
 
 # ADD CONFIGS HERE
 # --------------------------------------------------------------------
@@ -104,12 +110,10 @@ clean:
 	rm -rf build_*/
 
 # targets handled by cmake
-test: ;
-upload: ;
-package: ;
-package_source: ;
+cmake_targets = test upload package package_source debug check_weak
+$(foreach targ,$(cmake_targets),$(eval $(call cmake-targ,$(targ))))
 
-.PHONY: clean test upload package package_source
+.PHONY: clean
 
 CONFIGS:=$(shell ls cmake/configs | sed -e "s~.*/~~" | sed -e "s~\..*~~")
 
diff --git a/cmake/common/px4_base.cmake b/cmake/common/px4_base.cmake
index be3d449710..7e8ddabee0 100644
--- a/cmake/common/px4_base.cmake
+++ b/cmake/common/px4_base.cmake
@@ -551,6 +551,7 @@ function(px4_add_common_flags)
 	endif()
 
 	set(c_compile_flags
+		-g3
 		-std=gnu99
 		-fno-common
 		)
@@ -559,6 +560,7 @@ function(px4_add_common_flags)
 		-Wno-missing-field-initializers
 		)
 	set(cxx_compile_flags
+		-g3
 		-fno-exceptions
 		-fno-rtti
 		-std=gnu++0x
diff --git a/cmake/nuttx/bin_to_obj.py b/cmake/nuttx/bin_to_obj.py
index 07c81edcde..a4ad3d94df 100755
--- a/cmake/nuttx/bin_to_obj.py
+++ b/cmake/nuttx/bin_to_obj.py
@@ -55,10 +55,19 @@ run_cmd("{ld:s} -r -o {obj:s}.bin.o {obj:s}.c.o -b binary {in_bin:s}",
 
 # get size of image
 stdout = run_cmd("{nm:s} -p --radix=x {obj:s}.bin.o", locals())
-re_size = re.compile("(^[0-9A-Fa-f]*) .*{sym:s}_size".format(
-    **locals()))
-size_match = re.match(re_size, stdout)
-size = size_match.group(1)
+re_string = r"^([0-9A-F-a-f]+) .*{sym:s}_size\n".format(**locals())
+re_size = re.compile(re_string, re.MULTILINE)
+size_match = re.search(re_size, stdout)
+try:
+    size = size_match.group(1)
+except AttributeError as e:
+    raise RuntimeError("{:s}\nre:{:s}\n{:s}".format(
+        e, re_string, stdout))
+except IndexError as e:
+    group0 = size_match.group(0)
+    raise RuntimeError("{:s}\ngroup 0:{:s}\n{:s}".format(
+        e, group0, stdout))
+
 #print("romfs size: ", size)
 
 # write size to file
diff --git a/cmake/toolchains/Toolchain-arm-none-eabi.cmake b/cmake/toolchains/Toolchain-arm-none-eabi.cmake
index 13514080ad..5fab42f3c2 100644
--- a/cmake/toolchains/Toolchain-arm-none-eabi.cmake
+++ b/cmake/toolchains/Toolchain-arm-none-eabi.cmake
@@ -37,7 +37,7 @@ endif()
 cmake_force_cxx_compiler(${CXX_COMPILER} GNU)
 
 # compiler tools
-foreach(tool objcopy nm ld)
+foreach(tool objcopy nm ld gdb)
 	string(TOUPPER ${tool} TOOL)
 	find_program(${TOOL} arm-none-eabi-${tool})
 	if(NOT ${TOOL})
diff --git a/src/drivers/boards/aerocore/aerocore_spi.c b/src/drivers/boards/aerocore/aerocore_spi.c
index 5a4dd15b26..1ce3f35f88 100644
--- a/src/drivers/boards/aerocore/aerocore_spi.c
+++ b/src/drivers/boards/aerocore/aerocore_spi.c
@@ -67,7 +67,7 @@
  *
  ************************************************************************************/
 
-__EXPORT void weak_function stm32_spiinitialize(void)
+__EXPORT void stm32_spiinitialize(void)
 {
 #ifdef CONFIG_STM32_SPI1
 	stm32_configgpio(GPIO_SPI1_NSS);
diff --git a/src/drivers/boards/px4fmu-v1/px4fmu_spi.c b/src/drivers/boards/px4fmu-v1/px4fmu_spi.c
index 8ef17c36ed..2a444796ff 100644
--- a/src/drivers/boards/px4fmu-v1/px4fmu_spi.c
+++ b/src/drivers/boards/px4fmu-v1/px4fmu_spi.c
@@ -67,7 +67,7 @@
  *
  ************************************************************************************/
 
-__EXPORT void weak_function stm32_spiinitialize(void)
+__EXPORT void stm32_spiinitialize(void)
 {
 	stm32_configgpio(GPIO_SPI_CS_GYRO);
 	stm32_configgpio(GPIO_SPI_CS_ACCEL);
diff --git a/src/drivers/boards/px4fmu-v2/px4fmu_spi.c b/src/drivers/boards/px4fmu-v2/px4fmu_spi.c
index 64b9926b8d..a380e05bd5 100644
--- a/src/drivers/boards/px4fmu-v2/px4fmu_spi.c
+++ b/src/drivers/boards/px4fmu-v2/px4fmu_spi.c
@@ -67,7 +67,7 @@
  *
  ************************************************************************************/
 
-__EXPORT void weak_function stm32_spiinitialize(void)
+__EXPORT void stm32_spiinitialize(void)
 {
 #ifdef CONFIG_STM32_SPI1
 	stm32_configgpio(GPIO_SPI_CS_GYRO);
diff --git a/src/drivers/hmc5883/hmc5883.h b/src/drivers/hmc5883/hmc5883.h
index 9607fe6149..4cef0aa8cf 100644
--- a/src/drivers/hmc5883/hmc5883.h
+++ b/src/drivers/hmc5883/hmc5883.h
@@ -48,6 +48,6 @@
 #define ID_C_WHO_AM_I			'3'
 
 /* interface factories */
-extern device::Device *HMC5883_SPI_interface(int bus) weak_function;
-extern device::Device *HMC5883_I2C_interface(int bus) weak_function;
+extern device::Device *HMC5883_SPI_interface(int bus);
+extern device::Device *HMC5883_I2C_interface(int bus);
 typedef device::Device *(*HMC5883_constructor)(int);
diff --git a/src/drivers/ms5611/ms5611.h b/src/drivers/ms5611/ms5611.h
index a7e305b2aa..cc3e4c5920 100644
--- a/src/drivers/ms5611/ms5611.h
+++ b/src/drivers/ms5611/ms5611.h
@@ -80,7 +80,7 @@ extern bool crc4(uint16_t *n_prom);
 } /* namespace */
 
 /* interface factories */
-extern device::Device *MS5611_spi_interface(ms5611::prom_u &prom_buf, uint8_t busnum) __attribute__((weak));
-extern device::Device *MS5611_i2c_interface(ms5611::prom_u &prom_buf, uint8_t busnum) __attribute__((weak));
-extern device::Device *MS5611_sim_interface(ms5611::prom_u &prom_buf, uint8_t busnum) __attribute__((weak));
+extern device::Device *MS5611_spi_interface(ms5611::prom_u &prom_buf, uint8_t busnum);
+extern device::Device *MS5611_i2c_interface(ms5611::prom_u &prom_buf, uint8_t busnum);
+extern device::Device *MS5611_sim_interface(ms5611::prom_u &prom_buf, uint8_t busnum);
 typedef device::Device *(*MS5611_constructor)(ms5611::prom_u &prom_buf, uint8_t busnum);
diff --git a/src/firmware/nuttx/CMakeLists.txt b/src/firmware/nuttx/CMakeLists.txt
index 83d4a8ea14..8cf5e64b3b 100644
--- a/src/firmware/nuttx/CMakeLists.txt
+++ b/src/firmware/nuttx/CMakeLists.txt
@@ -31,11 +31,24 @@ target_link_libraries(firmware_nuttx
 
 set(fw_file ${CMAKE_CURRENT_BINARY_DIR}/${OS}-${BOARD}-${LABEL}.px4)
 
+add_custom_target(check_weak
+	COMMAND ${NM} firmware_nuttx | grep " w "
+	DEPENDS firmware_nuttx
+	)
+
 px4_nuttx_add_firmware(OUT ${fw_file}
-	EXE ${CMAKE_CURRENT_BINARY_DIR}/firmware_nuttx
+	EXE firmware_nuttx
 	${config_firmware_options}
 	)
 
+configure_file(gdbinit.in .gdbinit)
+
+add_custom_target(debug
+	COMMAND ${GDB} ${CMAKE_CURRENT_BINARY_DIR}/firmware_nuttx
+	DEPENDS firmware_nuttx
+		${CMAKE_CURRENT_BINARY_DIR}/.gdbinit
+	)
+
 px4_add_upload(OUT upload OS ${OS} BOARD ${BOARD}
 	BUNDLE ${fw_file})
 
diff --git a/src/firmware/nuttx/gdbinit.in b/src/firmware/nuttx/gdbinit.in
new file mode 100644
index 0000000000..a927caeed0
--- /dev/null
+++ b/src/firmware/nuttx/gdbinit.in
@@ -0,0 +1,7 @@
+target extended ${DEBUG_PORT}
+monitor swdp_scan
+attach 1
+monitor vector_catch disable hard
+set mem inaccessible-by-default off
+set print pretty
+source Debug/PX4
diff --git a/src/modules/uORB/uORB.h b/src/modules/uORB/uORB.h
index c887925fcf..6ead26186b 100644
--- a/src/modules/uORB/uORB.h
+++ b/src/modules/uORB/uORB.h
@@ -89,20 +89,14 @@ enum ORB_PRIO {
 /**
  * Declare (prototype) the uORB metadata for a topic.
  *
- * Note that optional topics are declared weak; this allows a potential
- * subscriber to attempt to subscribe to a topic that is not known to the
- * system at runtime.  The ORB_ID() macro will return NULL/nullptr for
- * such a topic, and attempts to advertise or subscribe to it will
- * return -1/ENOENT (see below).
- *
  * @param _name		The name of the topic.
  */
 #if defined(__cplusplus)
 # define ORB_DECLARE(_name)		extern "C" const struct orb_metadata __orb_##_name __EXPORT
-# define ORB_DECLARE_OPTIONAL(_name)	extern "C" const struct orb_metadata __orb_##_name __EXPORT __attribute__((weak))
+# define ORB_DECLARE_OPTIONAL(_name)	extern "C" const struct orb_metadata __orb_##_name __EXPORT
 #else
 # define ORB_DECLARE(_name)		extern const struct orb_metadata __orb_##_name __EXPORT
-# define ORB_DECLARE_OPTIONAL(_name)	extern const struct orb_metadata __orb_##_name __EXPORT __attribute__((weak))
+# define ORB_DECLARE_OPTIONAL(_name)	extern const struct orb_metadata __orb_##_name __EXPORT
 #endif
 
 /**