这是我的目录树：
tree ./
./
├── common
│ └── common.h
├── dir1
│ ├── a1.c
│ ├── a1.h
│ ├── b1.c
│ ├── b1.h
│ ├── c1.c
│ ├── c1.h
│ └── dir1.mk
├── makefile
└── sys-make
├── gcc.mk
└── rules.mk
每个c文件都包含它自己的头文件和公共标题，a1.c包括a1.h和common.h。我主要有4个makediles：
生成文件：
TOP_DIR = $(PWD)
MKFILE_DIR = $(TOP_DIR)/sys-make
OUTPUT_DIR = $(TOP_DIR)/output
export TOP_DIR MKFILE_DIR
all:
@echo "$(PWD)/makefile"
@echo "$(CC_DEFS)"
@$(MAKE) -f $(TOP_DIR)/dir1/dir1.mk
clean:
@$(MAKE) -f $(TOP_DIR)/dir1/dir1.mk clean
dir1.mk：
MODULE = dir1
MOD_LIB = ./lib$(MODULE).a
SRC_FILES =
SRC_FILES += a1.c
SRC_FILES += b1.c
SRC_FILES += c1.c
INC_PATH =
INC_PATH += $(TOP_DIR)/common
SRC_PATH =
SRC_PATH += $(TOP_DIR)/dir1
SRC_PATH += $(TOP_DIR)/dir1/sub_dir1
vpath %.c $(SRC_PATH)
include $(MKFILE_DIR)/gcc.mk
include $(MKFILE_DIR)/rules.mk
gcc.mk
CC :=
CC = gcc
CFLAG :=
CFLAG = -ggdb -Wall
rules.mk
OUTPUT_DIR = $(TOP_DIR)/output/$(MODULE)
OBJS = $(addprefix $(OUTPUT_DIR)/,$(SRC_FILES:.c=.o))
DEPS = $(addprefix $(OUTPUT_DIR)/,$(SRC_FILES:.c=.d))
$(OUTPUT_DIR)/$(MOD_LIB): $(OBJS)
@ar cr $@ $^
@echo "ar $@"
$(OUTPUT_DIR)/%.o: %.c
@echo "objs: $(OBJS)"
@echo "deps: $(DEPS)"
@echo "outs: $(OUTPUT_DIR)"
@mkdir -p $(OUTPUT_DIR)
$(CC) $(CFLAG) $(CC_DEFS) -I$(INC_PATH) -MM -MF $(patsubst %.o,%.d,$@) -o $@ $<
@echo "cc $(notdir $<)"
clean:
-@rm -r $(OUTPUT_DIR)
-include $(DEPS)
首次编译后，没有问题*.o，*.d和*.a生成到./output/dir1。问题是，无论我触摸*1.h还是common.h，都会显示：
make[1]: `/home/haochen/Work/test_code/test_makefile/output/dir1/./libdir1.a' is up to date.
似乎我的依赖文件有问题，当我cat a.d时，它显示：
cat output/dir1/a1.d
a1.o: /home/haochen/Work/test_code/test_makefile/dir1/a1.c \
/home/haochen/Work/test_code/test_makefile/dir1/a1.h \
/home/haochen/Work/test_code/test_makefile/common/common.h
我的makefile中的任何问题？我尝试将-MM -MF $(patsubst %.o,%.d,$@)替换为-MMD，但输出如下：
make
/home/haochen/Work/test_code/test_makefile/makefile
SYS1 SYS2 SYS3 SYS4
make[1]: Entering directory `/home/haochen/Work/test_code/test_makefile'
objs: /home/haochen/Work/test_code/test_makefile/output/dir1/a1.o /home/haochen/Work/test_code/test_makefile/output/dir1/b1.o /home/haochen/Work/test_code/test_makefile/output/dir1/c1.o
deps: /home/haochen/Work/test_code/test_makefile/output/dir1/a1.d /home/haochen/Work/test_code/test_makefile/output/dir1/b1.d /home/haochen/Work/test_code/test_makefile/output/dir1/c1.d
outs: /home/haochen/Work/test_code/test_makefile/output/dir1
gcc -ggdb -Wall -I /home/haochen/Work/test_code/test_makefile/common -MMD -o /home/haochen/Work/test_code/test_makefile/output/dir1/a1.o /home/haochen/Work/test_code/test_makefile/dir1/a1.c
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 0 has invalid symbol index 11
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 1 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 2 has invalid symbol index 2
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 3 has invalid symbol index 2
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 4 has invalid symbol index 11
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 5 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 6 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 7 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 8 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 9 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 10 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 11 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 12 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 13 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 14 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 15 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 16 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 17 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 18 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 19 has invalid symbol index 21
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_line): relocation 0 has invalid symbol index 2
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status
make[1]: *** [/home/haochen/Work/test_code/test_makefile/output/dir1/a1.o] Error 1
make[1]: Leaving directory `/home/haochen/Work/test_code/test_makefile'
make: *** [all] Error 2
答案 0 :(得分：1)
您可以在显示的.d文件的输出中看到问题：
a1.o: /home/haochen/Work/test_code/test_makefile/dir1/a1.c \
此处的目标是a1.o。但是，您实际构建的目标是$(OUTPUT_DIR)/a1.o。因此，make不会将这些额外的先决条件应用于该目标，因此它不会检查它们以确定它们在构建目标时是否已更改。
您需要将目标名称作为您正在构建的确切目标：您可以使用-MT选项。例如：
$(OUTPUT_DIR)/%.o: %.c
@mkdir -p $(OUTPUT_DIR)
$(CC) $(CFLAG) $(CC_DEFS) -I$(INC_PATH) -MM -MF $(patsubst %.o,%.d,$@) -MT $@ -o $@ $<
@echo "cc $(notdir $<)"