# PX4 build is via external build system ifneq ($(PX4_ROOT),) px4: make -C $(PX4_ROOT) EXTERNAL_APPS=$(PWD) px4-clean: clean make -C $(PX4_ROOT) EXTERNAL_APPS=$(PWD) clean px4-upload: make -C $(PX4_ROOT) EXTERNAL_APPS=$(PWD) upload else px4: $(error ERROR: You need to add PX4_ROOT to your config.mk) endif