make otapackage是从build/core/Makefile开始执行的:
$(INTERNAL_OTA_PACKAGE_TARGET): $(BUILT_TARGET_FILES_PACKAGE) $(DISTTOOLS)
@echo "Package OTA: $@"
$(hide) PATH=$(foreach p,$(INTERNAL_USERIMAGES_BINARY_PATHS),$(p):)$$PATH MKBOOTIMG=$(MKBOOTIMG) \
./build/tools/releasetools/ota_from_target_files -v -w \
-p $(HOST_OUT) \
-k $(KEY_CERT_PAIR) $(TIMESTAMP_CHECK) \