在本文中，描述一下caffe的Makefile檔案，這個檔案用於caffe的編譯；這裡不會把所有檔案都考過來，有些指令碼相似的會省略掉

檔案在caffe根目錄下，因為用到makefile.config中的變數，因此，在用到的時候我會給下說明

首先，是專案名稱

PROJECT := caffe #專案名稱，就是當前的caffe目錄

接下來，這個檔案要用到了Makefile.config中的一些變數，要包含這個檔案：

CONFIG_FILE := Makefile.config #配置檔名
# Explicitly check for the config file, otherwise make -k will proceed anyway.
ifeq ($(wildcard $(CONFIG_FILE)),) #檢查配置問價是否存在，如果不存在，使用config.example
$(error $(CONFIG_FILE) not found. See $(CONFIG_FILE).example.)
endif
include $(CONFIG_FILE) #將檔案包含進來
 

編譯後文件的存放目錄

BUILD_DIR_LINK := $(BUILD_DIR) #BUILD_DIR在Makefile.config檔案中定義　caffe中的build目錄

編譯方式：

ifeq ($(RELEASE_BUILD_DIR),) #是編譯方式，使用debug還是release編譯，如果用debug生成./build_debug目錄，release生成./build_release目錄
	RELEASE_BUILD_DIR := .$(BUILD_DIR)_release
endif
ifeq ($(DEBUG_BUILD_DIR),)
	DEBUG_BUILD_DIR := .$(BUILD_DIR)_debug
endif

#檢查debug是否為０,debug的定義在.config檔案中
DEBUG ?= 0
ifeq ($(DEBUG), 1)
	BUILD_DIR := $(DEBUG_BUILD_DIR)
	OTHER_BUILD_DIR := $(RELEASE_BUILD_DIR)
else
	BUILD_DIR := $(RELEASE_BUILD_DIR)
	OTHER_BUILD_DIR := $(DEBUG_BUILD_DIR)
endif
 

連結庫生成

# All of the directories containing code.找到所有.cpp .proto
SRC_DIRS := $(shell find * -type d -exec bash -c "find {} -maxdepth 1 \
	\( -name '*.cpp' -o -name '*.proto' \) | grep -q ." \; -print)

# The target shared library name
LIB_BUILD_DIR := $(BUILD_DIR)/lib #build/lib存放生成的連結庫
STATIC_NAME := $(LIB_BUILD_DIR)/lib$(PROJECT).a #生成靜態連結庫
DYNAMIC_NAME := $(LIB_BUILD_DIR)/lib$(PROJECT).so　#動態連結庫
 

獲取所有原始檔：

##############################
# Get all source files
##############################
# CXX_SRCS are the source files excluding the test ones.
CXX_SRCS := $(shell find src/$(PROJECT) ! -name "test_*.cpp" -name "*.cpp") #排除test_*.cpp
# CU_SRCS are the cuda source files
CU_SRCS := $(shell find src/$(PROJECT) ! -name "test_*.cu" -name "*.cu") #排除test_*.cu
# TEST_SRCS are the test source files
TEST_MAIN_SRC := src/$(PROJECT)/test/test_caffe_main.cpp #~/src/caffe/test/test_caffe_main.cpp
TEST_SRCS := $(shell find src/$(PROJECT) -name "test_*.cpp")
TEST_SRCS := $(filter-out $(TEST_MAIN_SRC), $(TEST_SRCS))
TEST_CU_SRCS := $(shell find src/$(PROJECT) -name "test_*.cu")
GTEST_SRC := src/gtest/gtest-all.cpp
# TOOL_SRCS are the source files for the tool binaries
TOOL_SRCS := $(shell find tools -name "*.cpp") #tools目錄下所有.cpp檔案
# EXAMPLE_SRCS are the source files for the example binaries
EXAMPLE_SRCS := $(shell find examples -name "*.cpp")
# BUILD_INCLUDE_DIR contains any generated header files we want to include.
BUILD_INCLUDE_DIR := $(BUILD_DIR)/src　#build/src, 包含include的標頭檔案。
# PROTO_SRCS are the protocol buffer definitions
PROTO_SRC_DIR := src/$(PROJECT)/proto　	#~/src/caffe/proto
PROTO_SRCS := $(wildcard $(PROTO_SRC_DIR)/*.proto)
# PROTO_BUILD_DIR will contain the .cc and obj files generated from
# PROTO_SRCS; PROTO_BUILD_INCLUDE_DIR will contain the .h header files
PROTO_BUILD_DIR := $(BUILD_DIR)/$(PROTO_SRC_DIR) #build/proto
PROTO_BUILD_INCLUDE_DIR := $(BUILD_INCLUDE_DIR)/$(PROJECT)/proto
# NONGEN_CXX_SRCS includes all source/header files except those generated
# NONGEN_CXX_SRCS　所有排除的檔案
# automatically (e.g., by proto).
NONGEN_CXX_SRCS := $(shell find \
	src/$(PROJECT) \
	include/$(PROJECT) \
	python/$(PROJECT) \
	matlab/+$(PROJECT)/private \
	examples \
	tools \
	-name "*.cpp" -or -name "*.hpp" -or -name "*.cu" -or -name "*.cuh")

後面一段LINT貌似是關於靜態程式碼解析的，還有一些是用於python和matlab介面的，這裡不做說明

匯出生成檔案：

這裡需要說一下編譯caffe的過程：從.cpp檔案，生成.o檔案，由.o檔案生成.bin檔案，同時，在生成.d的過程需要依賴.d檔案

因此，在build檔案中會由這三種字尾的檔案

##############################
# Derive generated files
##############################
# The generated files for protocol buffers
#caffe.pb.h，caffe.pb.cc在build/proto中
PROTO_GEN_HEADER_SRCS := $(addprefix $(PROTO_BUILD_DIR)/, \ 
		$(notdir ${PROTO_SRCS:.proto=.pb.h}))
PROTO_GEN_HEADER := $(addprefix $(PROTO_BUILD_INCLUDE_DIR)/, \
		$(notdir ${PROTO_SRCS:.proto=.pb.h}))
PROTO_GEN_CC := $(addprefix $(BUILD_DIR)/, ${PROTO_SRCS:.proto=.pb.cc})
PY_PROTO_BUILD_DIR := python/$(PROJECT)/proto
PY_PROTO_INIT := python/$(PROJECT)/proto/__init__.py
PROTO_GEN_PY := $(foreach file,${PROTO_SRCS:.proto=_pb2.py}, \
		$(PY_PROTO_BUILD_DIR)/$(notdir $(file)))
# The objects corresponding to the source files
# These objects will be linked into the final shared library, so we
# exclude the tool, example, and test objects.
CXX_OBJS := $(addprefix $(BUILD_DIR)/, ${CXX_SRCS:.cpp=.o})
CU_OBJS := $(addprefix $(BUILD_DIR)/cuda/, ${CU_SRCS:.cu=.o})
PROTO_OBJS := ${PROTO_GEN_CC:.cc=.o}
OBJS := $(PROTO_OBJS) $(CXX_OBJS) $(CU_OBJS)
# tool, example, and test objects
TOOL_OBJS := $(addprefix $(BUILD_DIR)/, ${TOOL_SRCS:.cpp=.o}) #定義生成規則，tools下的.cpp檔案生成.o檔案;檔案存放在build/tools中
#下面類似
TOOL_BUILD_DIR := $(BUILD_DIR)/tools
TEST_CXX_BUILD_DIR := $(BUILD_DIR)/src/$(PROJECT)/test
TEST_CU_BUILD_DIR := $(BUILD_DIR)/cuda/src/$(PROJECT)/test
TEST_CXX_OBJS := $(addprefix $(BUILD_DIR)/, ${TEST_SRCS:.cpp=.o})
TEST_CU_OBJS := $(addprefix $(BUILD_DIR)/cuda/, ${TEST_CU_SRCS:.cu=.o})
TEST_OBJS := $(TEST_CXX_OBJS) $(TEST_CU_OBJS)
GTEST_OBJ := $(addprefix $(BUILD_DIR)/, ${GTEST_SRC:.cpp=.o})
EXAMPLE_OBJS := $(addprefix $(BUILD_DIR)/, ${EXAMPLE_SRCS:.cpp=.o})
# Output files for automatic dependency generation
#　生成的依賴檔案是.d的
DEPS := ${CXX_OBJS:.o=.d} ${CU_OBJS:.o=.d} ${TEST_CXX_OBJS:.o=.d} \
	${TEST_CU_OBJS:.o=.d} $(BUILD_DIR)/${MAT$(PROJECT)_SO:.$(MAT_SO_EXT)=.d}
# tool, example, and test bins
TOOL_BINS := ${TOOL_OBJS:.o=.bin}　 #.o檔案生成.bin檔案
EXAMPLE_BINS := ${EXAMPLE_OBJS:.o=.bin}
# symlinks to tool bins without the ".bin" extension
TOOL_BIN_LINKS := ${TOOL_BINS:.bin=}
# Put the test binaries in build/test for convenience.
TEST_BIN_DIR := $(BUILD_DIR)/test
TEST_CU_BINS := $(addsuffix .testbin,$(addprefix $(TEST_BIN_DIR)/, \
		$(foreach obj,$(TEST_CU_OBJS),$(basename $(notdir $(obj))))))
TEST_CXX_BINS := $(addsuffix .testbin,$(addprefix $(TEST_BIN_DIR)/, \
		$(foreach obj,$(TEST_CXX_OBJS),$(basename $(notdir $(obj))))))
TEST_BINS := $(TEST_CXX_BINS) $(TEST_CU_BINS)
# TEST_ALL_BIN is the test binary that links caffe dynamically.
TEST_ALL_BIN := $(TEST_BIN_DIR)/test_all.testbin

再下來，生成警告檔案

##############################
# Derive compiler warning dump locations
# 警告檔案，.o.warnings.txt；編譯沒有問題生警告檔案為０字元
##############################
WARNS_EXT := warnings.txt
CXX_WARNS := $(addprefix $(BUILD_DIR)/, ${CXX_SRCS:.cpp=.o.$(WARNS_EXT)})
CU_WARNS := $(addprefix $(BUILD_DIR)/cuda/, ${CU_SRCS:.cu=.o.$(WARNS_EXT)})
TOOL_WARNS := $(addprefix $(BUILD_DIR)/, ${TOOL_SRCS:.cpp=.o.$(WARNS_EXT)})
EXAMPLE_WARNS := $(addprefix $(BUILD_DIR)/, ${EXAMPLE_SRCS:.cpp=.o.$(WARNS_EXT)})
TEST_WARNS := $(addprefix $(BUILD_DIR)/, ${TEST_SRCS:.cpp=.o.$(WARNS_EXT)})
TEST_CU_WARNS := $(addprefix $(BUILD_DIR)/cuda/, ${TEST_CU_SRCS:.cu=.o.$(WARNS_EXT)})
ALL_CXX_WARNS := $(CXX_WARNS) $(TOOL_WARNS) $(EXAMPLE_WARNS) $(TEST_WARNS)
ALL_CU_WARNS := $(CU_WARNS) $(TEST_CU_WARNS)
ALL_WARNS := $(ALL_CXX_WARNS) $(ALL_CU_WARNS)

EMPTY_WARN_REPORT := $(BUILD_DIR)/.$(WARNS_EXT)
NONEMPTY_WARN_REPORT := $(BUILD_DIR)/$(WARNS_EXT)

新增cuda的路徑

##############################
# Derive include and lib directories
# 匯出include和lib目錄
##############################
CUDA_INCLUDE_DIR := $(CUDA_DIR)/include

CUDA_LIB_DIR :=
# add <cuda>/lib64 only if it exists
#　新增cuda/lib64檔案路徑：如果你已經安裝了cuda
ifneq ("$(wildcard $(CUDA_DIR)/lib64)","")
	CUDA_LIB_DIR += $(CUDA_DIR)/lib64
endif
CUDA_LIB_DIR += $(CUDA_DIR)/lib

INCLUDE_DIRS += $(BUILD_INCLUDE_DIR) ./src ./include
ifneq ($(CPU_ONLY), 1)
	INCLUDE_DIRS += $(CUDA_INCLUDE_DIR)
	LIBRARY_DIRS += $(CUDA_LIB_DIR)
	LIBRARIES := cudart cublas curand
endif
LIBRARIES += glog gflags protobuf leveldb snappy \
	lmdb boost_system hdf5_hl hdf5 m \
	opencv_core opencv_highgui opencv_imgproc
PYTHON_LIBRARIES := boost_python python2.7
WARNINGS := -Wall -Wno-sign-compare

build文件目錄等

##############################
# Set build directories
# 設定build目錄
##############################

DISTRIBUTE_DIR ?= distribute
DISTRIBUTE_SUBDIRS := $(DISTRIBUTE_DIR)/bin $(DISTRIBUTE_DIR)/lib
DIST_ALIASES := dist
ifneq ($(strip $(DISTRIBUTE_DIR)),distribute)
		DIST_ALIASES += distribute
endif

ALL_BUILD_DIRS := $(sort $(BUILD_DIR) $(addprefix $(BUILD_DIR)/, $(SRC_DIRS)) \
	$(addprefix $(BUILD_DIR)/cuda/, $(SRC_DIRS)) \
	$(LIB_BUILD_DIR) $(TEST_BIN_DIR) $(PY_PROTO_BUILD_DIR) $(LINT_OUTPUT_DIR) \
	$(DISTRIBUTE_SUBDIRS) $(PROTO_BUILD_INCLUDE_DIR))

##############################
# Set directory for Doxygen-generated documentation
# 註釋文件什麼的
##############################
DOXYGEN_CONFIG_FILE ?= ./.Doxyfile
# should be the same as OUTPUT_DIRECTORY in the .Doxyfile
DOXYGEN_OUTPUT_DIR ?= ./doxygen
DOXYGEN_COMMAND ?= doxygen
# All the files that might have Doxygen documentation.
DOXYGEN_SOURCES := $(shell find \
	src/$(PROJECT) \
	include/$(PROJECT) \
	python/ \
	matlab/ \
	examples \
	tools \
	-name "*.cpp" -or -name "*.hpp" -or -name "*.cu" -or -name "*.cuh" -or \
        -name "*.py" -or -name "*.m")
DOXYGEN_SOURCES += $(DOXYGEN_CONFIG_FILE)

作業系統（只貼下linux部分的）

##############################
# Configure build
# 作業系統
##############################

# Determine platform
UNAME := $(shell uname -s)
ifeq ($(UNAME), Linux) #對於linux系統
	LINUX := 1
else ifeq ($(UNAME), Darwin) #ios
	OSX := 1
endif

# Linux
ifeq ($(LINUX), 1)
	CXX ?= /usr/bin/g++ #是否有g++
	GCCVERSION := $(shell $(CXX) -dumpversion | cut -f1,2 -d.)
	# older versions of gcc are too dumb to build boost with -Wuninitalized
	ifeq ($(shell echo | awk '{exit $(GCCVERSION) < 4.6;}'), 1) #如果g++版本<4.6需要新增一些配置
		WARNINGS += -Wno-uninitialized
	endif
	# boost::thread is reasonably called boost_thread (compare OS X)
	# We will also explicitly add stdc++ to the link target.
	LIBRARIES += boost_thread stdc++ #新增boost_thread和stdc++
endif

後面一大堆配置，如自定義編譯，矩陣運算包之類；

# Custom compiler
# 自定義編譯
ifdef CUSTOM_CXX
	CXX := $(CUSTOM_CXX)
endif

# Static linking
# 靜態連結庫
ifneq (,$(findstring clang++,$(CXX)))
	STATIC_LINK_COMMAND := -Wl,-force_load $(STATIC_NAME)
else ifneq (,$(findstring g++,$(CXX)))
	STATIC_LINK_COMMAND := -Wl,--whole-archive $(STATIC_NAME) -Wl,--no-whole-archive
else
  # The following line must not be indented with a tab, since we are not inside a target
  $(error Cannot static link with the $(CXX) compiler)
endif

# Debugging
ifeq ($(DEBUG), 1)
	COMMON_FLAGS += -DDEBUG -g -O0
	NVCCFLAGS += -G
else
	COMMON_FLAGS += -DNDEBUG -O2
endif

# cuDNN acceleration configuration.
ifeq ($(USE_CUDNN), 1)
	LIBRARIES += cudnn
	COMMON_FLAGS += -DUSE_CUDNN
endif

# CPU-only configuration
# 只有CPU下的配置
ifeq ($(CPU_ONLY), 1)
	OBJS := $(PROTO_OBJS) $(CXX_OBJS)
	TEST_OBJS := $(TEST_CXX_OBJS)
	TEST_BINS := $(TEST_CXX_BINS)
	ALL_WARNS := $(ALL_CXX_WARNS)
	TEST_FILTER := --gtest_filter="-*GPU*"
	COMMON_FLAGS += -DCPU_ONLY
endif

# Python layer support
ifeq ($(WITH_PYTHON_LAYER), 1)
	COMMON_FLAGS += -DWITH_PYTHON_LAYER
	LIBRARIES += $(PYTHON_LIBRARIES)
endif

# BLAS configuration (default = ATLAS)
# 矩陣運算庫，預設ATLAS
BLAS ?= atlas
ifeq ($(BLAS), mkl)
	# MKL
	LIBRARIES += mkl_rt
	COMMON_FLAGS += -DUSE_MKL
	MKL_DIR ?= /opt/intel/mkl
	BLAS_INCLUDE ?= $(MKL_DIR)/include
	BLAS_LIB ?= $(MKL_DIR)/lib $(MKL_DIR)/lib/intel64
else ifeq ($(BLAS), open)
	# OpenBLAS
	LIBRARIES += openblas
else
	# ATLAS
	ifeq ($(LINUX), 1)
		ifeq ($(BLAS), atlas)
			# Linux simply has cblas and atlas
			LIBRARIES += cblas atlas
		endif
	else ifeq ($(OSX), 1)
		# OS X packages atlas as the vecLib framework
		LIBRARIES += cblas
		# 10.10 has accelerate while 10.9 has veclib
		XCODE_CLT_VER := $(shell pkgutil --pkg-info=com.apple.pkg.CLTools_Executables | grep -o 'version: 6')
		ifneq (,$(findstring version: 6,$(XCODE_CLT_VER)))
			BLAS_INCLUDE ?= /System/Library/Frameworks/Accelerate.framework/Versions/Current/Frameworks/vecLib.framework/Headers/
			LDFLAGS += -framework Accelerate
		else
			BLAS_INCLUDE ?= /System/Library/Frameworks/vecLib.framework/Versions/Current/Headers/
			LDFLAGS += -framework vecLib
		endif
	endif
endif
INCLUDE_DIRS += $(BLAS_INCLUDE)
LIBRARY_DIRS += $(BLAS_LIB)

LIBRARY_DIRS += $(LIB_BUILD_DIR)

後面一句是為了寫.d檔案

# Automatic dependency generation (nvcc is handled separately)
CXXFLAGS += -MMD -MP　#生成依賴
##
# build資料夾的子目錄中會有.d檔案，MMD生成這個檔案的前半段：.build.......
# MP生成了後面include ...:　的內容
# 第一次編譯時，會編譯所有檔案，而如果include中的內容由改變時，不會重新生成.d.
##

以build/src/bolb.b為例：

MMD生成了：

.build_debug/src/caffe/blob.o: src/caffe/blob.cpp include/caffe/blob.hpp \
 include/caffe/common.hpp include/caffe/util/device_alternate.hpp \
 /usr/local/cuda/include/cublas_v2.h /usr/local/cuda/include/cublas_api.h \
 /usr/local/cuda/include/driver_types.h \.......................

MP生了：

include/caffe/blob.hpp:
include/caffe/common.hpp:
include/caffe/util/device_alternate.hpp:...................................

然後直到下面定義編譯目標：

這裡，就是make xx的東西了

##############################
# Define build targets
#　定義編譯目標，就是make執行的內容
##############################
# make
#如果make後面什麼都不加，就執行所有的all test clean.....
.PHONY: all test clean docs linecount lint lintclean tools examples $(DIST_ALIASES) \
	py mat py$(PROJECT) mat$(PROJECT) proto runtest \
	superclean supercleanlist supercleanfiles warn everything

# make all
all: $(STATIC_NAME) $(DYNAMIC_NAME) tools examples
....................

以tools為例子，解釋一下這部分做的事情：

tools: $(TOOL_BINS) $(TOOL_BIN_LINKS)

這裡的意思是說，如果你執行make tools，會做：右邊的兩件事情，$(TOOL_BIN)和$(TOOL_BIN_LINKS)其實是兩個規則，具體定義如下：

$(TOOL_BINS): %.bin : %.o | $(DYNAMIC_NAME)
	@ echo CXX/LD -o [email protected]
	$(Q)$(CXX) $< -o [email protected] $(LINKFLAGS) -l$(PROJECT) $(LDFLAGS) \
		-Wl,-rpath,$(ORIGIN)/../lib

檔案中的標識中：[email protected]目標檔案，$^--所有的依賴檔案，$<--第一個依賴檔案。

echo後面的內容，是make後在命令視窗中打印出來的內容

$(Q)在Makefile.config的最後定義：預設不列印後面的內容，將這裡註釋掉，就可以打印出所有內容

# enable pretty build (comment to see full commands)
Q ?= @

%.o：是個萬用字元，表示所有的.o檔案，這幾步是把.o檔案生成.bin檔案

| : 是一種依賴規則：當不存在目標檔案時，所有的依賴都會被執行，生成目標檔案，當存在目標時，若修改依賴中的內容，目標檔案不會被重新建立。即｜後面的依賴是一種很弱的依賴，

Makefile中的內容大致就是這樣，現在，註釋掉Makefile.config中的$(Q),執行：

make 2>&1 >out.log　

２是錯誤的輸出，１為正確的輸出，這句的意思是將所有編譯的內容全部輸出到out.log中

將所有內容列印到out.log檔案中，看一下caffe.cpp檔案的執行過程：

CXX tools/caffe.cpp
g++ tools/caffe.cpp -MMD -MP -pthread -fPIC -DDEBUG -g -O0 -DUSE_OPENCV -DUSE_LEVELDB -DUSE_LMDB -I/usr/include/python2.7 -I/usr/lib/python2.7/dist-packages/numpy/core/include -I/usr/local/include -I.build_debug/src -I./src -I./include -I/usr/local/cuda-7.5/include -Wall -Wno-sign-compare -c -o .build_debug/tools/caffe.o 2> .build_debug/tools/caffe.o.warnings.txt \
		|| (cat .build_debug/tools/caffe.o.warnings.txt; exit 1)
CXX/LD -o .build_debug/tools/caffe.bin
g++ .build_debug/tools/caffe.o -o .build_debug/tools/caffe.bin -pthread -fPIC -DDEBUG -g -O0 -DUSE_OPENCV -DUSE_LEVELDB -DUSE_LMDB -I/usr/include/python2.7 -I/usr/lib/python2.7/dist-packages/numpy/core/include -I/usr/local/include -I.build_debug/src -I./src -I./include -I/usr/local/cuda-7.5/include -Wall -Wno-sign-compare -lcaffe -L/home/sindyz/anaconda/lib -L/usr/local/lib -L/usr/lib -L/usr/local/cuda-7.5/lib64 -L/usr/local/cuda-7.5/lib -L.build_debug/lib  -lcudart -lcublas -lcurand -lglog -lgflags -lprotobuf -lboost_system -lboost_filesystem -lm -lhdf5_hl -lhdf5 -lleveldb -lsnappy -llmdb -lopencv_core -lopencv_highgui -lopencv_imgproc -lboost_thread -lstdc++ -lcblas -latlas \
		-Wl,-rpath,\$ORIGIN/../lib

這裡，第一個g++後面的內容，是從.cpp檔案生成.o檔案的過程，可以看到相應的連結庫和配置資訊

第二個g++後面的內容是.o檔案到.bin的生成過程。

由此，我們可以自己寫caffe的程式碼並且配置Makefile了。

初學caffe，由一些地方說明的不清楚的不對的，希望大家一起討論，共同進步。