Android编译过程详解(二)

     Android编译过程详解(一):http://www.cnblogs.com/mr-raptor/archive/2012/06/07/2540359.html

    Android编译过程详解(二):http://www.cnblogs.com/mr-raptor/archive/2012/06/08/2541571.html

    Android编译过程详解(三):http://www.cnblogs.com/mr-raptor/archive/2012/06/12/2547030.html

 

通过上篇文章,我们分析了编译android时source build/envsetup.sh和lunch命令,在执行完上述两个命令后, 我们就可以进行编译android了。

 

1. make 

执行make命令的结果就是去执行当前目录下的Makefile文件,我们来看下它的内容:

?
### DO NOT EDIT THIS FILE ###
include build/core/main.mk
### DO NOT EDIT THIS FILE ###


呵呵,看到上面 的内容,我们都会笑,这是我见过最简单的Makefile了,我们再看下build/core/main.mk

main.mk文件里虽然脚本不多,但是却定义了整个Android的编译关系,它主要引入了下列几个重要的mk文件:

49 include $(BUILD_SYSTEM)/config.mk

55 include $(BUILD_SYSTEM)/cleanbuild.mk

142 include $(BUILD_SYSTEM)/definitions.mk

当然每个mk文件都有自己独特的意义,我们一并将主线流程相关mk文件都列出来,大概来介绍下,先有个整体的概念,然后再细化了解。

Android编译过程详解(二)_第1张图片

所有的Makefile都通过build/core/main.mk这个文件组织在一起,它定义了一个默认goals:droid,当我们在TOP目录下,敲Make实际上就等同于我们执行make droid。

当Make include所有的文件,完成对所有make我文件的解析以后就会寻找生成droid的规则,依次生成它的依赖,直到所有满足的模块被编译好,然后使用相应的工具打包成相应的img。其中,config.mk,envsetup.mk,product_config.mk文件是编译用户指定平台系统的关键文件。上图中红色部分是用户指定平台产品的编译主线,我们先来看下config.mk的主要作用。

 

2. build/core/config.mk

该文件被main.mk包含。

定义了以下环境变量:

?
16 SRC_HEADERS := \
  17     $(TOPDIR) system /core/include \
  18     $(TOPDIR)hardware/libhardware/include \
  19     $(TOPDIR)hardware/libhardware_legacy/include \
  20     $(TOPDIR)hardware/ril/include \
  21     $(TOPDIR)dalvik/libnativehelper/include \
  22     $(TOPDIR)frameworks/base/include \
  23     $(TOPDIR)frameworks/base/opengl/include \
  24     $(TOPDIR)external/skia/include
  25 SRC_HOST_HEADERS:=$(TOPDIR)tools/include
  26 SRC_LIBRARIES:= $(TOPDIR)libs
  27 SRC_SERVERS:= $(TOPDIR)servers
  28 SRC_TARGET_DIR := $(TOPDIR)build/target
  29 SRC_API_DIR := $(TOPDIR)frameworks/base/api
.....然后定义了下面几个重要的编译命令 43 CLEAR_VARS:= $(BUILD_SYSTEM)/clear_vars.mk
  44 BUILD_HOST_STATIC_LIBRARY:= $(BUILD_SYSTEM)/host_static_library.mk
  45 BUILD_HOST_SHARED_LIBRARY:= $(BUILD_SYSTEM)/host_shared_library.mk
  46 BUILD_STATIC_LIBRARY:= $(BUILD_SYSTEM)/static_library.mk
  47 BUILD_RAW_STATIC_LIBRARY := $(BUILD_SYSTEM)/raw_static_library.mk
  48 BUILD_SHARED_LIBRARY:= $(BUILD_SYSTEM)/shared_library.mk
  49 BUILD_EXECUTABLE:= $(BUILD_SYSTEM)/executable.mk
  50 BUILD_RAW_EXECUTABLE:= $(BUILD_SYSTEM)/raw_executable.mk
  51 BUILD_HOST_EXECUTABLE:= $(BUILD_SYSTEM)/host_executable.mk
  52 BUILD_PACKAGE:= $(BUILD_SYSTEM)/package.mk
  53 BUILD_HOST_PREBUILT:= $(BUILD_SYSTEM)/host_prebuilt.mk
  54 BUILD_PREBUILT:= $(BUILD_SYSTEM)/prebuilt.mk
  55 BUILD_MULTI_PREBUILT:= $(BUILD_SYSTEM)/multi_prebuilt.mk
  56 BUILD_JAVA_LIBRARY:= $(BUILD_SYSTEM)/java_library.mk
  57 BUILD_STATIC_JAVA_LIBRARY:= $(BUILD_SYSTEM)/static_java_library.mk
  58 BUILD_HOST_JAVA_LIBRARY:= $(BUILD_SYSTEM)/host_java_library.mk
  59 BUILD_DROIDDOC:= $(BUILD_SYSTEM)/droiddoc.mk
  60 BUILD_COPY_HEADERS := $(BUILD_SYSTEM)/copy_headers.mk
  61 BUILD_KEY_CHAR_MAP := $(BUILD_SYSTEM)/key_char_map.mk

 

 上述命令变量其实是对应的mk文件名,所有的Android.mk文件里基本上都包含上述命令变量,如:

CLEAR_VARS:用来清除之前定义的环境变量

BUILD_SHARED_LIBRARY:用来指定编译动态库过程

?
109 # ---------------------------------------------------------------
110 # Define most of the global variables.  These are the ones that
111 # are specific to the user's build configuration.
112 include $(BUILD_SYSTEM)/envsetup.mk
113
114 # Boards may be defined under $(SRC_TARGET_DIR)/board/$(TARGET_DEVICE)
115 # or under vendor /*/$(TARGET_DEVICE).  Search in both places, but
116 # make sure only one exists.
117 # Real boards should always be associated with an OEM vendor.
118 board_config_mk := \
119     $(strip $(wildcard \
120         $(SRC_TARGET_DIR)/board/$(TARGET_DEVICE)/BoardConfig.mk \
121         vendor/*/ $(TARGET_DEVICE)/BoardConfig.mk \
122     ))
123 ifeq ($(board_config_mk),)
124   $(error No config file found for TARGET_DEVICE $(TARGET_DEVICE))
125 endif
126 ifneq ($(words $(board_config_mk)),1)
127   $(error Multiple board config files for TARGET_DEVICE $(TARGET_DEVICE): $(board_config_mk))
128 endif
129 include $(board_config_mk)
130 TARGET_DEVICE_DIR := $(patsubst %/,%,$(dir $(board_config_mk)))
131 board_config_mk :=

 

112行又包含了另外一个重要的mk文件envsetup.mk,我们来看一下。

 

3. envsetup.mk

 

复制代码
 25 ifeq ($(TARGET_PRODUCT),)    #判断TARGET_PRODUCT是否为空,
 26 ifeq ($(TARGET_SIMULATOR),true)
 27 TARGET_PRODUCT := sim
 28 else
 29 TARGET_PRODUCT := generic
 30 endif
 31 endif
复制代码

 

第25行,判断TARGET_PRODUCT是否为空,根据上一节分析可知,TARGET_PRODUCT=fs100 

复制代码
 34 # the variant -- the set of files that are included for a build
 35 ifeq ($(strip $(TARGET_BUILD_VARIANT)),)
 36 TARGET_BUILD_VARIANT := eng
 37 endif
 38 
 39 # Read the product specs so we an get TARGET_DEVICE and other
 40 # variables that we need in order to locate the output files.
 41 include $(BUILD_SYSTEM)/product_config.mk
复制代码

 

在41行又包含了product_config.mk文件,等会我们再分析它,先看下面的

 

复制代码
148 # ---------------------------------------------------------------
149 # figure out the output directories
150 
151 ifeq (,$(strip $(OUT_DIR)))
152 OUT_DIR := $(TOPDIR)out
153 endif
154 
155 DEBUG_OUT_DIR := $(OUT_DIR)/debug
156 
157 # Move the host or target under the debug/ directory
158 # if necessary.
159 TARGET_OUT_ROOT_release := $(OUT_DIR)/target
160 TARGET_OUT_ROOT_debug := $(DEBUG_OUT_DIR)/target
161 TARGET_OUT_ROOT := $(TARGET_OUT_ROOT_$(TARGET_BUILD_TYPE))
162 
...
184 PRODUCT_OUT := $(TARGET_PRODUCT_OUT_ROOT)/$(TARGET_DEVICE)
187 
188 HOST_OUT_EXECUTABLES:= $(HOST_OUT)/bin
189 HOST_OUT_SHARED_LIBRARIES:= $(HOST_OUT)/lib
190 HOST_OUT_JAVA_LIBRARIES:= $(HOST_OUT)/framework
191 HOST_OUT_SDK_ADDON := $(HOST_OUT)/sdk_addon
...
200 TARGET_OUT_INTERMEDIATES := $(PRODUCT_OUT)/obj
201 TARGET_OUT_HEADERS:= $(TARGET_OUT_INTERMEDIATES)/include
202 TARGET_OUT_INTERMEDIATE_LIBRARIES := $(TARGET_OUT_INTERMEDIATES)/lib
203 TARGET_OUT_COMMON_INTERMEDIATES := $(TARGET_COMMON_OUT_ROOT)/obj
204 
205 TARGET_OUT := $(PRODUCT_OUT)/system
206 TARGET_OUT_EXECUTABLES:= $(TARGET_OUT)/bin
207 TARGET_OUT_OPTIONAL_EXECUTABLES:= $(TARGET_OUT)/xbin
208 TARGET_OUT_SHARED_LIBRARIES:= $(TARGET_OUT)/lib
209 TARGET_OUT_JAVA_LIBRARIES:= $(TARGET_OUT)/framework
210 TARGET_OUT_APPS:= $(TARGET_OUT)/app
211 TARGET_OUT_KEYLAYOUT := $(TARGET_OUT)/usr/keylayout
212 TARGET_OUT_KEYCHARS := $(TARGET_OUT)/usr/keychars
213 TARGET_OUT_ETC := $(TARGET_OUT)/etc
214 TARGET_OUT_STATIC_LIBRARIES:= $(TARGET_OUT_INTERMEDIATES)/lib
215 TARGET_OUT_NOTICE_FILES:=$(TARGET_OUT_INTERMEDIATES)/NOTICE_FILES
216 
217 TARGET_OUT_DATA := $(PRODUCT_OUT)/data
218 TARGET_OUT_DATA_EXECUTABLES:= $(TARGET_OUT_EXECUTABLES)
219 TARGET_OUT_DATA_SHARED_LIBRARIES:= $(TARGET_OUT_SHARED_LIBRARIES)
220 TARGET_OUT_DATA_JAVA_LIBRARIES:= $(TARGET_OUT_JAVA_LIBRARIES)
221 TARGET_OUT_DATA_APPS:= $(TARGET_OUT_DATA)/app
222 TARGET_OUT_DATA_KEYLAYOUT := $(TARGET_OUT_KEYLAYOUT)
223 TARGET_OUT_DATA_KEYCHARS := $(TARGET_OUT_KEYCHARS)
224 TARGET_OUT_DATA_ETC := $(TARGET_OUT_ETC)
225 TARGET_OUT_DATA_STATIC_LIBRARIES:= $(TARGET_OUT_STATIC_LIBRARIES)
226 
227 TARGET_OUT_UNSTRIPPED := $(PRODUCT_OUT)/symbols
228 TARGET_OUT_EXECUTABLES_UNSTRIPPED := $(TARGET_OUT_UNSTRIPPED)/system/bin
229 TARGET_OUT_SHARED_LIBRARIES_UNSTRIPPED := $(TARGET_OUT_UNSTRIPPED)/system/lib
230 TARGET_ROOT_OUT_UNSTRIPPED := $(TARGET_OUT_UNSTRIPPED)
231 TARGET_ROOT_OUT_SBIN_UNSTRIPPED := $(TARGET_OUT_UNSTRIPPED)/sbin
232 TARGET_ROOT_OUT_BIN_UNSTRIPPED := $(TARGET_OUT_UNSTRIPPED)/bin
233 
234 TARGET_ROOT_OUT := $(PRODUCT_OUT)/root
235 TARGET_ROOT_OUT_BIN := $(TARGET_ROOT_OUT)/bin
236 TARGET_ROOT_OUT_SBIN := $(TARGET_ROOT_OUT)/sbin
237 TARGET_ROOT_OUT_ETC := $(TARGET_ROOT_OUT)/etc
238 TARGET_ROOT_OUT_USR := $(TARGET_ROOT_OUT)/usr
239 
240 TARGET_RECOVERY_OUT := $(PRODUCT_OUT)/recovery
241 TARGET_RECOVERY_ROOT_OUT := $(TARGET_RECOVERY_OUT)/root
242 
243 TARGET_SYSLOADER_OUT := $(PRODUCT_OUT)/sysloader
244 TARGET_SYSLOADER_ROOT_OUT := $(TARGET_SYSLOADER_OUT)/root
245 TARGET_SYSLOADER_SYSTEM_OUT := $(TARGET_SYSLOADER_OUT)/root/system
246 
247 TARGET_INSTALLER_OUT := $(PRODUCT_OUT)/installer
248 TARGET_INSTALLER_DATA_OUT := $(TARGET_INSTALLER_OUT)/data
249 TARGET_INSTALLER_ROOT_OUT := $(TARGET_INSTALLER_OUT)/root
250 TARGET_INSTALLER_SYSTEM_OUT := $(TARGET_INSTALLER_OUT)/root/system
复制代码

 

上面的代码是指定了目标输出代码的位置和主机输出代码的位置,重要的几个如下:

 

复制代码
PRODUCT_OUT = 这个的结果要根据product_config.mk文件内容来决定,其实是out/target/product/fs100/
TARGET_OUT = $(PRODUCT_OUT)/system
TARGET_OUT_EXECUTABLES =  $(PRODUCT_OUT)/system/bin
TARGET_OUT_SHARED_LIBRARIES =  $(PRODUCT_OUT)/system/lib
TARGET_OUT_JAVA_LIBRARIES = $(PRODUCT_OUT)/system/framework
TARGET_OUT_APPS = $(PRODUCT_OUT)/system/app
TARGET_OUT_ETC = $(PRODUCT_OUT)/system/etc
TARGET_OUT_STATIC_LIBRARIES  = $(PRODUCT_OUT)/obj/lib
TARGET_OUT_DATA = $(PRODUCT_OUT)/data
TARGET_OUT_DATA_APPS = $(PRODUCT_OUT)/data/app
TARGET_ROOT_OUT = $(PRODUCT_OUT)/root
TARGET_ROOT_OUT_BIN = $(PRODUCT_OUT)/bin
TARGET_ROOT_OUT_SBIN  = $(PRODUCT_OUT)/system/sbin
TARGET_ROOT_OUT_ETC = $(PRODUCT_OUT)/system/etc
TARGET_ROOT_OUT_USR = $(PRODUCT_OUT)/system/usr
复制代码

 

总结下:

envsetup.mk文件主要包含了product_config.mk文件,然后指定了编译时要输出的所有文件的OUT目录。


4. build/core/product_config.mk

 

复制代码
157 include $(BUILD_SYSTEM)/product.mk
...
160 # Read in all of the product definitions specified by the AndroidProducts.mk
161 # files in the tree.
162 #
163 #TODO: when we start allowing direct pointers to product files,
164 #    guarantee that they're in this list.
165 $(call import-products, $(get-all-product-makefiles))
166 $(check-all-products)
...
170 # Convert a short name like "sooner" into the path to the product
171 # file defining that product.
172 #
173 INTERNAL_PRODUCT := $(call resolve-short-product-name, $(TARGET_PRODUCT))
...
176 # Find the device that this product maps to.
177 TARGET_DEVICE := $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_DEVICE)
复制代码

 

157行,我靠,又包含了product.mk文件

 

165行,调用函数import-products, $(get-all-product-makefiles),这儿我们看上面的注释:

复制代码
    Read in all of the product definitions specified by the AndroidProducts.mk files in the tree.
    TODO: when we start allowing direct pointers to product files, guarantee that they're in this list.
复制代码

 

    意思是说:读取指定的目录下所有的AndrodProducts.mk文件中定义的产品信息

    其实get-all-product-makefiles返回所有的产品文件xxx.mk

    import-products函数去验证这些产品配置文件是否都包含有必须的配置信息,细节后面分析。

173行调用了resolve-short-product-name函数,它将返回TARGET_PRODUCT产品的配置文件目录,并赋给INTERNAL_PRODUCT

    也就是说:

复制代码
    INTERNAL_PRODUCT = vendor/farsight/products/fs100.mk
    TARGET_DEVICE = fs100
复制代码

       如果调试看其结果,可以在167行,将#$(dump-product)取消注释

     然后在175行添加: $(info $(INTERNAL_PRODUCT))

       在178行添加: $(info $(TARGET_DEVICE )),查看调试结果。

总结一下:

接合前面的图,product_config.mk主要读取vendor目录下不同厂商自己定义的AndrodProducts.mk文件,从该文件里取得所有产品的配置文件,然后再根据lunch选择的编译项TARGET_PRODUCT,找到与之对应的配置文件,然后设置TARGET_DEVICE变量,用于后续编译。

 

5. build/core/product.mk

 

复制代码
17 #
 18 # Functions for including AndroidProducts.mk files
 19 #
 20 
 21 #
 22 # Returns the list of all AndroidProducts.mk files.
 23 # $(call ) isn't necessary.
 24 #
 25 define _find-android-products-files
 26 $(shell test -d vendor && find vendor -maxdepth 6 -name AndroidProducts.mk) \
 27   $(SRC_TARGET_DIR)/product/AndroidProducts.mk
 28 endef
 29 
 30 #
 31 # Returns the sorted concatenation of all PRODUCT_MAKEFILES
 32 # variables set in all AndroidProducts.mk files.
 33 # $(call ) isn't necessary.
 34 #
 35 define get-all-product-makefiles
 36 $(sort \
 37   $(foreach f,$(_find-android-products-files), \
 38     $(eval PRODUCT_MAKEFILES :=) \
 39     $(eval LOCAL_DIR := $(patsubst %/,%,$(dir $(f)))) \
 40     $(eval include $(f)) \
 41     $(PRODUCT_MAKEFILES) \
 42    ) \
 43   $(eval PRODUCT_MAKEFILES :=) \
 44   $(eval LOCAL_DIR :=) \
 45  )
 46 endef
复制代码

 

 通过注释可知,本文件中主要是一些用来处理AndroidProduct.mk的函数
_find-android-products-files:

    用来获得vendor目录下,所有名字为AndroidProduct.mk的文件列表。
get-all-product-makefiles:

    用来获得所有AndroidProduct.mk文件里定义的PRODUCT_MAKEFILES的值(其实是产品文件路径名)。


在vendor目录下,每个公司目录下都会存在一个AndroidProduct.mk文件,这个文件是用来定义这个公司的产品列表,每个产品用<product_name>.mk来表示
如Android给的示例:

vendor/sample/products/AndroidProduct.mk

其内容如下:

复制代码
1 #
  2 # This file should set PRODUCT_MAKEFILES to a list of product makefiles
  3 # to expose to the build system.  LOCAL_DIR will already be set to
  4 # the directory containing this file. 
  5 #
  6 # This file may not rely on the value of any variable other than
  7 # LOCAL_DIR; do not use any conditionals, and do not look up the
  8 # value of any variable that isn't set in this file or in a file that
  9 # it includes.
 10 #
 11 
 12 PRODUCT_MAKEFILES := \
 13   $(LOCAL_DIR)/sample_addon.mk
复制代码

 

  里面只定义了一个产品配置文件,即当前目录下的sample_addon.mk:
复制代码
  1 # List of apps and optional libraries (Java and native) to put in the add-on system image.
  2 PRODUCT_PACKAGES := \
  3     PlatformLibraryClient \
  4     com.example.android.platform_library \
  5     libplatform_library_jni
复制代码

 

上述文件里定义了产品相关个性化信息,如,PRODUCT_PACKAGES表示要在当前产品里添加一些安装包。
由此可见,get-all-product-makefiles函数,其实就是返回了当前公司里全部的产品对应的mk文件列表。

 


总结:

如果用户想个性定制自己的产品,应该有以下流程,包含上一节内容:

1. 创建公司目录

    #mkdir vendor/farsight

2. 创建一个vendorsetup.sh文件,将当前产品编译项添加到lunch里,让lunch能找到用户个性定制编译项

    #echo "add_lunch_combo fs100-eng" > vendor/farsight/vendorsetup.sh

3. 仿着Android示例代码,在公司目录下创建products目录

    #mkdir -p vendor/farsight/products

4. 仿着Android示例代码,在products目录下创建两个mk文件

    #touch vendor/farsight/products/AndroidProduct.mk vendor/farsight/products/fs100.mk

在AndroidProduct.mk里添加如下内容:

 

PRODUCT_MAKEFILES := $(LOCAL_DIR)/fs100.mk

表示只有一个产品fs100,它对应的配置文件在当前目录下的fs100.mk。

 

5. 在产品配置文件里添加最基本信息

 

复制代码
  1 
  2 PRODUCT_PACKAGES := \
  3     IM \
  4     VoiceDialer
  5 
  6 $(call inherit-product, build/target/product/generic.mk)  ##从某一默认配置开始派生余下内容参考派生起点
  7 
  8 # Overrides
  9 PRODUCT_MANUFACTURER := farsight
 10 PRODUCT_NAME := fs100
 11 PRODUCT_DEVICE := fs100
复制代码

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