Allow change of debug flags without forcing complete rebuild (betafli…

…ght#13708)

Makefile

@@ -34,7 +34,7 @@ CUSTOM_DEFAULTS_EXTENDED ?= no
 
 # Debugger optons:
 #   empty - ordinary build with all optimizations enabled
-#   INFO - ordinary build with debug symbols and all optimizations enabled
+#   INFO - ordinary build with debug symbols and all optimizations enabled. Only builds touched files.
 #   GDB - debug build with minimum number of optimizations
 DEBUG     ?=
 
@@ -142,6 +142,15 @@ EXTRA_LD_FLAGS  :=
 #
 # Default Tool options - can be overridden in {mcu}.mk files.
 #
+DEBUG_MIXED = no
+
+ifeq ($(DEBUG),INFO)
+DEBUG_MIXED = yes
+endif
+ifeq ($(DEBUG),GDB)
+DEBUG_MIXED = yes
+endif
+
 ifeq ($(DEBUG),GDB)
 OPTIMISE_DEFAULT      := -Og
 
@@ -336,7 +345,12 @@ TARGET_MAP      = $(OBJECT_DIR)/$(FORKNAME)_$(TARGET_NAME).map
 
 TARGET_EXST_HASH_SECTION_FILE = $(TARGET_OBJ_DIR)/exst_hash_section.bin
 
+ifeq ($(DEBUG_MIXED),yes)
+TARGET_EF_HASH      := $(shell echo -n -- "$(EXTRA_FLAGS)" "$(OPTIONS)" "$(DEVICE_FLAGS)" "$(TARGET_FLAGS)"  | openssl dgst -md5 -r | awk '{print $$1;}')
+else
 TARGET_EF_HASH      := $(shell echo -n -- "$(EXTRA_FLAGS)" "$(OPTIONS)" "$(DEBUG_FLAGS)" "$(DEVICE_FLAGS)" "$(TARGET_FLAGS)"  | openssl dgst -md5 -r | awk '{print $$1;}')
+endif
+
 TARGET_EF_HASH_FILE := $(TARGET_OBJ_DIR)/.efhash_$(TARGET_EF_HASH)
 
 CLEAN_ARTIFACTS := $(TARGET_BIN)