Makefile文件的规则

格式TARGET:PREFEQUISTES COMMANDS

main.c 
#include <stdio.h>
#include <utility.h>

int main(int argc,char *argv[]){
    printf("%d",getNumber());
    return 0;
}

utility.h
int getNumber();

utility.c
int getNumber(){
    return 2;
}

例子

SimpleMakefile:main.o utility.o     gcc -o SimpleMakefile main.o utility.o
main.o:main.c   gcc -c main.c
utility.o:utility.c gcc -c utility.c

Makefile(另一种写法)
OBEJCT=main.o utility.o

SimpleMakefile:$(OBEJCT)	gcc -o SimpleMakefile $(OBEJCT)

Android 系统的编译：

1. 1.Makefile->build/core/main.mk

2. main.mk的droid流程
   APP:droid->app_only->$(unbunled_build_modules)
   系统:droid->droidcore
   ->dist_files

3. main.mk的定制文件（处理属性 零件）
   vendorsetup.sh (出现在envsetup.sh)
   AndroidProducts.mk
   BoardConfig.mk
   Android.mk (出现在main.mk)

4. droidcore编译过程

# 生成droidcore的过程 主要files 与最后一个生成的installed-files.txt记录预安装程序模块
# 负责生成系统的所有可执行程序包 如system.img boot.img recovery.img等
.PHONY: droidcore
droidcore: files     systemimage     $(INSTALLED_BOOTIMAGE_TARGET)     $(INSTALLED_RECOVERYIMAGE_TARGET)     $(INSTALLED_USERDATAIMAGE_TARGET)     $(INSTALLED_CACHEIMAGE_TARGET)     $(INSTALLED_VENDORIMAGE_TARGET)     $(INSTALLED_FILES_FILE)

------------------------------files-----------------------------------------
# 重点看files生成过程
# prebuilt 该机制用于早期版本
.PHONY: files
files: prebuilt         $(modules_to_install)         $(INSTALLED_ANDROID_INFO_TXT_TARGET)

# 描述系统需要安装的模块
# product_FILES各modules安装文件的列表
# tags_to_install 通过标志选择性编译的模块
# get-tagged-modules 判断目标是否有“拒绝”标签，如果有 则不被编译
modules_to_install := $(sort     $(ALL_DEFAULT_INSTALLED_MODULES)     $(product_FILES)     $(foreach tag,$(tags_to_install),$($(tag)_MODULES))     $(call get-tagged-modules, shell_$(TARGET_SHELL))     $(CUSTOM_MODULES)   )
----------------------------------------------------------------------------

------------------------------systemimage-----------------------------------
# 该定义在build/core/Makefile
# BUILT_SYSTEMIMAGE := $(systemimage_intermediates)/system.img   最终生成system.img文件
# $@ 代表target的集合
$(INSTALLED_SYSTEMIMAGE): $(BUILT_SYSTEMIMAGE) $(RECOVERY_FROM_BOOT_PATCH) | $(ACP)
    @echo "Install system fs image: $@"
    $(copy-file-to-target)
    $(hide) $(call assert-max-image-size,$@ $(RECOVERY_FROM_BOOT_PATCH),$(BOARD_SYSTEMIMAGE_PARTITION_SIZE),yaffs)

systemimage: $(INSTALLED_SYSTEMIMAGE)
----------------------------------------------------------------------------

1. dist_files编译过程

# 在out目录下生成dist文件夹用于存储多种分发包 
# dist_files only for putting your library into the dist directory with a full build.
.PHONY: dist_files

Android.mk系统例子

• 以 $(源码)\system\core\adb 项目的android.mk为例

# Copyright 2005 The Android Open Source Project
#
# Android.mk for adb
#

LOCAL_PATH:= $(call my-dir)

# adb host tool
# =========================================================
# CLEAR_VARS清除上百个LOCAL_PATH外的变量
include $(CLEAR_VARS)

# Default to a virtual (sockets) usb interface
# 定义usb驱动
USB_SRCS :=
EXTRA_SRCS :=

ifeq ($(HOST_OS),linux)
  USB_SRCS := usb_linux.c
  EXTRA_SRCS := get_my_path_linux.c
  LOCAL_LDLIBS += -lrt -ldl -lpthread
  LOCAL_CFLAGS += -DWORKAROUND_BUG6558362
endif

ifeq ($(HOST_OS),darwin)
  USB_SRCS := usb_osx.c
  EXTRA_SRCS := get_my_path_darwin.c
  LOCAL_LDLIBS += -lpthread -framework CoreFoundation -framework IOKit -framework Carbon
endif

ifeq ($(HOST_OS),freebsd)
  USB_SRCS := usb_libusb.c
  EXTRA_SRCS := get_my_path_freebsd.c
  LOCAL_LDLIBS += -lpthread -lusb
endif

ifeq ($(HOST_OS),windows)
  USB_SRCS := usb_windows.c
  EXTRA_SRCS := get_my_path_windows.c ../libcutils/list.c
  EXTRA_STATIC_LIBS := AdbWinApi
  ifneq ($(strip $(USE_CYGWIN)),)
    # Pure cygwin case
    LOCAL_LDLIBS += -lpthread -lgdi32
    LOCAL_C_INCLUDES += /usr/include/w32api/ddk
  endif
  ifneq ($(strip $(USE_MINGW)),)
    # MinGW under Linux case
    LOCAL_LDLIBS += -lws2_32 -lgdi32
    USE_SYSDEPS_WIN32 := 1
    LOCAL_C_INCLUDES += /usr/i586-mingw32msvc/include/ddk
  endif
  LOCAL_C_INCLUDES += development/host/windows/usb/api/
endif

# 定义本模块所用到的所有源文件 包括上面用的驱动变量
LOCAL_SRC_FILES :=     adb.c     console.c     transport.c     transport_local.c     transport_usb.c     commandline.c     adb_client.c     adb_auth_host.c     sockets.c     services.c     file_sync_client.c     $(EXTRA_SRCS)     $(USB_SRCS)     usb_vendors.c

LOCAL_C_INCLUDES += external/openssl/include

ifneq ($(USE_SYSDEPS_WIN32),)
  LOCAL_SRC_FILES += sysdeps_win32.c
else
  LOCAL_SRC_FILES += fdevent.c
endif

LOCAL_CFLAGS += -O2 -g -DADB_HOST=1  -Wall -Wno-unused-parameter
LOCAL_CFLAGS += -D_XOPEN_SOURCE -D_GNU_SOURCE
# 所要生成的模块名称
LOCAL_MODULE := adb
LOCAL_MODULE_TAGS := debug
# 编译需要用到的库
LOCAL_STATIC_LIBRARIES := libzipfile libunz libcrypto_static $(EXTRA_STATIC_LIBS)
ifeq ($(USE_SYSDEPS_WIN32),)
    LOCAL_STATIC_LIBRARIES += libcutils
endif

# 表示生成一个Host可执行文件
include $(BUILD_HOST_EXECUTABLE)

$(call dist-for-goals,dist_files sdk,$(LOCAL_BUILT_MODULE))

ifeq ($(HOST_OS),windows)
$(LOCAL_INSTALLED_MODULE):     $(HOST_OUT_EXECUTABLES)/AdbWinApi.dll     $(HOST_OUT_EXECUTABLES)/AdbWinUsbApi.dll
endif


# adbd device daemon
# =========================================================
# 第二个模块编译开始标志
include $(CLEAR_VARS)

LOCAL_SRC_FILES :=     adb.c     backup_service.c     fdevent.c     transport.c     transport_local.c     transport_usb.c     adb_auth_client.c     sockets.c     services.c     file_sync_service.c     jdwp_service.c     framebuffer_service.c     remount_service.c     usb_linux_client.c     log_service.c

LOCAL_CFLAGS := -O2 -g -DADB_HOST=0 -Wall -Wno-unused-parameter
LOCAL_CFLAGS += -D_XOPEN_SOURCE -D_GNU_SOURCE

ifneq (,$(filter userdebug eng,$(TARGET_BUILD_VARIANT)))
LOCAL_CFLAGS += -DALLOW_ADBD_ROOT=1
endif

# 所要生成的模块名称
LOCAL_MODULE := adbd

LOCAL_FORCE_STATIC_EXECUTABLE := true
LOCAL_MODULE_PATH := $(TARGET_ROOT_OUT_SBIN)
LOCAL_UNSTRIPPED_PATH := $(TARGET_ROOT_OUT_SBIN_UNSTRIPPED)

LOCAL_STATIC_LIBRARIES := liblog libcutils libc libmincrypt

# 生成adbd可执行文件
include $(BUILD_EXECUTABLE)

Android.mk变量解析