build: rebuild objects that depend on modified headers

Makefile

@@ -43,6 +43,9 @@ ASMFLAGS := $(ASMFLAGS) -DBUILD_ID=\"$(BUILD_ID)\"
 LDFLAGS := $(LDFLAGS) -g
 
 ALL_KERNEL_OBJECT_FILES := $(KERNEL_OBJ) $(ARCH_OBJ) $(LIBC_OBJ)
+ALL_KERNEL_DEPS := $(ALL_KERNEL_OBJECT_FILES:.o=.d)
+
+-include $(ALL_KERNEL_DEPS)
 
 all: $(BUILD_DIR)/$(KERNEL_EXEC) sandbox
 
@@ -54,12 +57,12 @@ $(BUILD_DIR)/$(KERNEL_EXEC): $(ALL_KERNEL_OBJECT_FILES)
 $(BUILD_DIR)/%.o: %.S
 	@printf "    \033[1;32mAS\033[0m     \033[35m$(KERNEL_EXEC)\033[0m/$<\n"
 	@mkdir -p $(@D)
-	@$(ASM) $< -o $@ -c $(ASMFLAGS) $(ARCH_ASMFLAGS)
+	@$(ASM) $< -o $@ -c $(ASMFLAGS) $(ARCH_ASMFLAGS) -MMD
 
 $(BUILD_DIR)/%.o: %.c
 	@printf "    \033[1;32mCC\033[0m     \033[35m$(KERNEL_EXEC)\033[0m/$<\n"
 	@mkdir -p $(@D)
-	@$(CC) $< -o $@ -c $(CFLAGS) $(ARCH_CFLAGS)
+	@$(CC) $< -o $@ -c $(CFLAGS) $(ARCH_CFLAGS) -MMD
 
 clean:
 	@printf "    \033[1;93mRM\033[0m     Deleting build files.\n"

sandbox/Makefile

@@ -10,6 +10,7 @@ DIR_LIST := memblock vm base queue btree util
 INCLUDE_DIRS := $(foreach dir,$(DIR_LIST),-I$(dir)/include)
 SRC := $(foreach dir,$(DIR_LIST),$(wildcard $(dir)/*.c))
 OBJ := $(addprefix $(BUILD_DIR)/,$(SRC:.c=.o))
+DEPS := $(OBJ:.o=.d)
 
 CFLAGS := $(INCLUDE_DIRS) -g
 
@@ -22,12 +23,14 @@ $(BUILD_DIR)/$(EXEC_NAME): $(OBJ)
 	@mkdir -p $(@D)
 
 	@printf "    \033[1;36mHOSTLD\033[0m \033[1mbuild/sandbox/\033[35m$(EXEC_NAME)\n"
-	@$(CC) $^ -o $@ $(CFLAGS) $(LDFLAGS)
+	@$(CC) $(OBJ) -o $@ $(CFLAGS) $(LDFLAGS)
+
+-include $(DEPS)
 
 $(BUILD_DIR)/%.o: %.c
 	@printf "    \033[1;32mHOSTCC\033[0m \033[35msandbox\033[0m/$<\n"
 	@mkdir -p $(@D)
 
-	@$(CC) $< -o $@ -c $(CFLAGS)
+	@$(CC) $< -o $@ -c $(CFLAGS) -MMD
 
 .PHONY: all