Android编译系统过程研究

大家平时用虚拟机编译Android系统源码的时候，无非就是下面三个步骤：

<!–[if !supportLists]–>1、<!–[endif]–>执行source build/envsetup.sh命令

<!–[if !supportLists]–>2、<!–[endif]–>执行lunch命令，选择需要编译的系统版本

<!–[if !supportLists]–>3、<!–[endif]–>执行make命令，然后就是编译你选择好的系统版本

那么研究Android的编译过程，无非也就是研究这三个步骤各自做了哪些操作。

接下来，将会对这三个步骤进行详细的分析。

一、bulid/envsetup.sh脚本分析

source build/envsetup.sh这个命令就是将envsetup.sh定义的所有命令加载到环境变量中，像后面要使用的lunch、make命令就是这里定义的。打开这个脚本文件，发现里面定义了很多函数（以function为开头），下面分析一下主要函数的一些功能：

function hmm()：显示帮助信息，列出所有支持的命令，比如lunch、mm、mmm等

function get_abs_build_var()：获取编译时一些变量的绝对路径（比如BUILD_SYSTEM）

function get_build_var()：获取编译时一些变量的路径

function check_product()：检查产品是否支持编译

function check_variant()：检查变量variant是否有效，只能是user、userdebug、eng

function setpaths()：设置一些文件路径，并将一些编译所需的路径添加到环境变量中去

function printconfig()：打印配置信息

function set_sequence_number()：设置BUILD_ENV_SEQUENCE_NUMBER的值

function settitle()：设置PROMPT_COMMAND的值

function set_java_home()：设置java主目录

function set_stuff_for_environment()：调用setpaths、settitle、set_java_home、set_sequence_number函数，并设置ANDROID_BUILD_TOP值为Android源码目录

function choosetype()：选择编译类型，release和debug中的一个

function chooseproduct()：用户输入编译产品

function choosevariant()：用户选择variant，只能是user、userdebug、eng中的一个

function choosecombo()：调用choosetype、chooseproduct、choosevariant等函数

function add_lunch_combo()：增加lunch命令的选择项

function print_lunch_menu()：打印lunch命令可选择的项目列表

function lunch()：lunch命令的执行逻辑

function gettop()：获取Android源码根目录

function m()：m命令的执行逻辑

function findmakefile()：查找当前目录下Android.mk文件路径

function mm()：mm命令的执行逻辑

function mmm()：mmm命令的执行逻辑

function croot()：进入Android源码根目录

function pid()：查看某个进程的id

function runtest()：执行测试脚本

function godir ()：进入用户输入文件的所在目录

function set_java_home()：设置环境变量JAVA_HOME

除了定义了很多函数之外，还执行了下面的操作：

for f in `test -d device && find -L device -maxdepth 4 -name ‘vendorsetup.sh’ 2> /dev/null` \

`test -d vendor && find -L vendor -maxdepth 4 -name ‘vendorsetup.sh’ 2> /dev/null`

echo “including $f”

. $f

done

unset f

addcompletions

这里的操作就是查找vendor目录和device目录下的vendorsetup.sh文件，查找到之后就执行这些脚本文件。addcompletions函数主要是查找sdk/bash_completion目录下所有的.bash文件，找到之后执行这些文件。

1.1、执行vendorsetup.sh

vendorsetup.sh脚本都是类似“add_lunch_combo sp7731geaplus_dt-userdebug”这样的内容，也就是调用add_lunch_combo这个函数，将各自产品添加到LUNCH_MENU_CHOICES变量中去。

1.2、执行.bash脚本

这些脚本

主要是为命令提供tab支持，有了这些tab支持，输入命令后如果某个选项忘记了，只需要敲tab键，就能获得提示，使用命令更加方便

。例如

sdk/bash_completion/adb.bash

就是为

adb命令提供tab键提示功能。

二、lunch命令

接下来就分析一下lunch命令的流程，找到

envsetup.sh脚本中lunch函数：

function lunch()

{

local answer

if [ “$1” ] ; then

answer=$1

else

#如果没有输入参数，则打印出产品列表，让用户选择

print_lunch_menu

echo -n “Which would you like? [aosp_arm-eng] ”

read answer

local selection=

if [ -z “$answer” ]

then

selection=aosp_arm-eng #默认产品为aosp_arm-eng

elif (echo -n $answer | grep -q -e “^[0-9][0-9]*$”)

#用户输入的是数字

then

if [ $answer -le ${#LUNCH_MENU_CHOICES[@]} ]

then

selection=${LUNCH_MENU_CHOICES[$(($answer-1))]}

elif (echo -n $answer | grep -q -e “^[^\-][^\-]*-[^\-][^\-]*$”)

#用户输入的是文字

then

selection=$answer

if [ -z “$selection” ]

then

echo

echo “Invalid lunch combo: $answer”

return 1

export TARGET_BUILD_APPS=

#从用户的选择中提取出product

local product=$(echo -n $selection | sed -e “s/-.*$//”)

#检查产品是否支持

check_product $product

#如果不支持

if [ $? -ne 0 ]

then

echo

echo “** Don’t have a product spec for: ‘$product'”

echo “** Do you have the right repo manifest?”

product=

#从用户选择中提取出variant

local variant=$(echo -n $selection | sed -e “s/^[^\-]*-//”)

#检查variant是否支持

check_variant $variant

if [ $? -ne 0 ]

then

echo

echo “** Invalid variant: ‘$variant'”

echo “** Must be one of ${VARIANT_CHOICES[@]}”

variant=

if [ -z “$product” -o -z “$variant” ]

then

echo

return 1

#设置相关环境变量的属性

export TARGET_PRODUCT=$product

export TARGET_BUILD_VARIANT=$variant

export TARGET_BUILD_TYPE=release

echo

#设置编译相关环境变量属性

set_stuff_for_environment

#打印配置信息

printconfig

}

<!–[if !supportLists]–>三、<!–[endif]–>make命令

Make命令就是去执行Android源码根目录下是Makefile脚本，脚本内容如下：

### DO NOT EDIT THIS FILE ###

include build/core/main.mk

### DO NOT EDIT THIS FILE ###

意思就是去加载并执行build/core/main.mk脚本。

接下来分析main.mk脚本的执行流程：

<!–[if !supportLists]–>1、<!–[endif]–>根据ANDROID_BUILD_SHELL的定义来选择编译系统需要的SHELL，分别为/bin/sh和/bin/bash

ifdef ANDROID_BUILD_SHELL

SHELL := $(ANDROID_BUILD_SHELL)

else

SHELL := /bin/bash

endif

<!–[if !supportLists]–>2、<!–[endif]–>检查MAKE_VERSION，必须大于或等于3.81

ifeq (,$(findstring CYGWIN,$(shell uname -sm)))

ifneq (1,$(strip $(shell expr $(MAKE_VERSION) \>= 3.81)))

endif

<!–[if !supportLists]–>3、<!–[endif]–>定义一些编译时所需的变量值和默认目标droid（make命令不加任何参数就执行这个）

PWD := $(shell pwd)

TOP := .

TOPDIR :=

BUILD_SYSTEM := $(TOPDIR)build/core

BUILD_SYSTEM_VENDOR := $(TOPDIR)build/vendor

.PHONY: droid

DEFAULT_GOAL := droid

$(DEFAULT_GOAL):

<!–[if !supportLists]–>4、<!–[endif]–>加载一些其他的.mk脚本

include $(BUILD_SYSTEM)/help.mk

include $(BUILD_SYSTEM)/config.mk

include $(BUILD_SYSTEM)/cleanbuild.mk

<!–[if !supportLists]–>5、<!–[endif]–>检查java版本、jdk版本、javac版本

ifeq ($(LEGACY_USE_JAVA6),)

required_version := “1.7.x”

required_javac_version := “1.7”

java_version := $(shell echo ‘$(java_version_str)’ | grep ‘^java .*[ “]1\.7[\. “$$]’)

javac_version := $(shell echo ‘$(javac_version_str)’ | grep ‘[ “]1\.7[\. “$$]’)

else # if LEGACY_USE_JAVA6

required_version := “1.6.x”

required_javac_version := “1.6”

java_version := $(shell echo ‘$(java_version_str)’ | grep ‘^java .*[ “]1\.6[\. “$$]’)

javac_version := $(shell echo ‘$(javac_version_str)’ | grep ‘[ “]1\.6[\. “$$]’)

endif # if LEGACY_USE_JAVA6

ifeq ($(strip $(java_version)),)

$(info ************************************************************)

$(info You are attempting to build with the incorrect version)

$(info of java.)

$(info $(space))

$(info Your version is: $(java_version_str).)

$(info The required version is: $(required_version))

$(info $(space))

$(info Please follow the machine setup instructions at)

$(info $(space)$(space)$(space)$(space)https://source.android.com/source/initializing.html)

$(info ************************************************************)

$(error stop)

endif

ifeq ($(requires_openjdk), true)

ifeq ($(shell echo ‘$(java_version_str)’ | grep -i openjdk),)

$(info ************************************************************)

$(info You asked for an OpenJDK 7 build but your version is)

$(info $(java_version_str).)

$(info ************************************************************)

$(error stop)

endif # java version is not OpenJdk

else # if requires_openjdk

ifneq ($(shell echo ‘$(java_version_str)’ | grep -i openjdk),)

$(info ************************************************************)

$(info You are attempting to build with an unsupported JDK.)

$(info $(space))

$(info You use OpenJDK but only Sun/Oracle JDK is supported.)

$(info Please follow the machine setup instructions at)

$(info $(space)$(space)$(space)$(space)https://source.android.com/source/download.html)

$(info ************************************************************)

$(error stop)

endif # java version is not Sun Oracle JDK

endif # if requires_openjdk

ifeq ($(strip $(javac_version)),)

$(info ************************************************************)

$(info You are attempting to build with the incorrect version)

$(info of javac.)

$(info $(space))

$(info Your version is: $(javac_version_str).)

$(info The required version is: $(required_javac_version))

$(info $(space))

$(info Please follow the machine setup instructions at)

$(info $(space)$(space)$(space)$(space)https://source.android.com/source/download.html)

$(info ************************************************************)

$(error stop)

endif

6、加载一些.mk脚本，并确定好TARGET_BUILD_VARIANT变量的值（user/userdebug/eng）

include $(BUILD_SYSTEM)/definitions.mk

include $(BUILD_SYSTEM)/dex_preopt.mk

ifneq ($(filter user userdebug eng,$(MAKECMDGOALS)),)

$(info ***************************************************************)

$(info Do not pass ‘$(filter user userdebug eng,$(MAKECMDGOALS))’ on \

the make command line.)

$(info Set TARGET_BUILD_VARIANT in buildspec.mk, or use lunch or)

$(info choosecombo.)

$(info ***************************************************************)

$(error stopping)

endif

ifneq ($(filter-out $(INTERNAL_VALID_VARIANTS),$(TARGET_BUILD_VARIANT)),)

$(info ***************************************************************)

$(info Invalid variant: $(TARGET_BUILD_VARIANT)

$(info Valid values are: $(INTERNAL_VALID_VARIANTS)

$(info ***************************************************************)

$(error stopping)

endif

<!–[if !supportLists]–>7、<!–[endif]–>确定is_sdk_build的值（后面需要用到）

is_sdk_build :=

ifneq ($(filter sdk win_sdk sdk_addon,$(MAKECMDGOALS)),)

is_sdk_build := true

endif

<!–[if !supportLists]–>8、<!–[endif]–>根据TARGET_BUILD_VARIANT的值，设置不同的ro属性

user_variant := $(filter user userdebug,$(TARGET_BUILD_VARIANT))

enable_target_debugging := true

tags_to_install :=

ifneq (,$(user_variant))

ADDITIONAL_DEFAULT_PROPERTIES += ro.secure=1

ifeq ($(user_variant),userdebug)

tags_to_install += debug

ADDITIONAL_BUILD_PROPERTIES += dalvik.vm.lockprof.threshold=500

else

enable_target_debugging :=

endif

ifeq (,$(WITH_DEXPREOPT))

ifeq ($(DALVIK_VM_LIB),libdvm.so)

ifeq ($(user_variant),user)

ifeq ($(HOST_OS),linux)

WITH_DEXPREOPT := true

endif

else # !user_variant

ADDITIONAL_BUILD_PROPERTIES += ro.kernel.android.checkjni=1

ADDITIONAL_DEFAULT_PROPERTIES += ro.secure=0

ADDITIONAL_DEFAULT_PROPERTIES += ro.allow.mock.location=1

endif # !user_variant

ifeq (true,$(strip $(enable_target_debugging)))

ADDITIONAL_DEFAULT_PROPERTIES += ro.debuggable=1

INCLUDE_TEST_OTA_KEYS := true

else # !enable_target_debugging

ADDITIONAL_DEFAULT_PROPERTIES += ro.debuggable=0

endif # !enable_target_debugging

ifeq ($(TARGET_BUILD_VARIANT),eng)

tags_to_install := debug eng

ifneq ($(filter ro.setupwizard.mode=ENABLED, $(call collapse-pairs, $(ADDITIONAL_BUILD_PROPERTIES))),)

# Don’t require the setup wizard on eng builds

ADDITIONAL_BUILD_PROPERTIES := $(filter-out ro.setupwizard.mode=%,\

$(call collapse-pairs, $(ADDITIONAL_BUILD_PROPERTIES))) \

ro.setupwizard.mode=OPTIONAL

endif

ifndef is_sdk_build

ADDITIONAL_BUILD_PROPERTIES += dalvik.vm.image-dex2oat-filter=verify-none

ADDITIONAL_BUILD_PROPERTIES += dalvik.vm.dex2oat-filter=interpret-only

endif

9、判断是否sdk编译，如果是则检查MAKECMDGOALS的值并设置一些属性的值

ifdef is_sdk_build

sdk_repo_goal := $(strip $(filter sdk_repo,$(MAKECMDGOALS)))

MAKECMDGOALS := $(strip $(filter-out sdk_repo,$(MAKECMDGOALS)))

ifneq ($(words $(filter-out $(INTERNAL_MODIFIER_TARGETS) checkbuild emulator_tests target-files-package,$(MAKECMDGOALS))),1)

$(error The ‘sdk’ target may not be specified with any other targets)

endif

tags_to_install := debug eng

ADDITIONAL_BUILD_PROPERTIES += xmpp.auto-presence=true

ADDITIONAL_BUILD_PROPERTIES += ro.config.nocheckin=yes

else # !sdk

endif

<!–[if !supportLists]–>10、<!–[endif]–>判断PRODUCT_TAGS的值，然后设置虚拟机的一些参数

ifneq ($(filter dalvik.gc.type-precise,$(PRODUCT_TAGS)),)

ADDITIONAL_BUILD_PROPERTIES += dalvik.vm.dexopt-flags=m=y

endif

ADDITIONAL_BUILD_PROPERTIES += net.bt.name=Android

ADDITIONAL_BUILD_PROPERTIES += dalvik.vm.stack-trace-file=/data/anr/traces.txt

11、通过findleaves.py工具查找subdir下所有的mk文件

subdir_makefiles := \

$(shell build/tools/findleaves.py –prune=$(OUT_DIR) –prune=.repo –prune=.git $(subdirs) Android.mk)

$(foreach mk, $(subdir_makefiles), $(info including $(mk) …)$(eval include $(mk)))

<!–[if !supportLists]–>12、<!–[endif]–>加载一些.mk文件

include $(BUILD_SYSTEM)/post_clean.mk

ifeq ($(stash_product_vars),true)

$(call assert-product-vars, __STASHED)

endif

include $(BUILD_SYSTEM)/legacy_prebuilts.mk

ifneq ($(filter-out $(GRANDFATHERED_ALL_PREBUILT),$(strip $(notdir $(ALL_PREBUILT)))),)

$(warning *** Some files have been added to ALL_PREBUILT.)

$(warning *)

$(warning * ALL_PREBUILT is a deprecated mechanism that)

$(warning * should not be used for new files.)

$(warning * As an alternative, use PRODUCT_COPY_FILES in)

$(warning * the appropriate product definition.)

$(warning * build/target/product/core.mk is the product)

$(warning * definition used in all products.)

$(warning *)

$(foreach bad_prebuilt,$(filter-out $(GRANDFATHERED_ALL_PREBUILT),$(strip $(notdir $(ALL_PREBUILT)))),$(warning * unexpected $(bad_prebuilt) in ALL_PREBUILT))

$(warning *)

$(error ALL_PREBUILT contains unexpected files)

endif

<!–[if !supportLists]–>13、<!–[endif]–>处理编译依赖，包含32位/64位系统的编译

define get-32-bit-modules

$(strip $(foreach m,$(1),\

$(if $(ALL_MODULES.$(m)$(TARGET_2ND_ARCH_MODULE_SUFFIX).CLASS),\

$(m)$(TARGET_2ND_ARCH_MODULE_SUFFIX))))

endef

define get-32-bit-modules-if-we-can

$(strip $(foreach m,$(1),\

$(if $(ALL_MODULES.$(m)$(TARGET_2ND_ARCH_MODULE_SUFFIX).CLASS),\

$(m)$(TARGET_2ND_ARCH_MODULE_SUFFIX),

$(m))))

endef

$(foreach m,$(ALL_MODULES),\

$(eval r := $(ALL_MODULES.$(m).REQUIRED))\

$(if $(r),\

$(if $(ALL_MODULES.$(m).FOR_2ND_ARCH),\

$(eval r_r := $(call get-32-bit-modules-if-we-can,$(r))),\

$(if $(filter EXECUTABLES SHARED_LIBRARIES,$(ALL_MODULES.$(m).CLASS)),\

$(eval r_r := $(r)),\

$(eval r_r := $(r) $(call get-32-bit-modules,$(r)))\

$(eval ALL_MODULES.$(m).REQUIRED := $(strip $(r_r)))\

)

r_r :=

define add-required-deps

$(1): | $(2)

endef

14、根据FULL_BUILD的值，确定product_FILES和product_MODULES的值

ifdef FULL_BUILD

product_MODULES := $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_PACKAGES)

# Filter out the overridden packages before doing expansion

product_MODULES := $(filter-out $(foreach p, $(product_MODULES), \

$(PACKAGES.$(p).OVERRIDES)), $(product_MODULES))

# Resolve the :32 :64 module name

modules_32 := $(patsubst %:32,%,$(filter %:32, $(product_MODULES)))

modules_64 := $(patsubst %:64,%,$(filter %:64, $(product_MODULES)))

modules_rest := $(filter-out %:32 %:64,$(product_MODULES))

# Note for 32-bit product, $(modules_32) and $(modules_64) will be

# added as their original module names.

product_MODULES := $(call get-32-bit-modules-if-we-can, $(modules_32))

product_MODULES += $(modules_64)

# For the rest we add both

product_MODULES += $(call get-32-bit-modules, $(modules_rest))

product_MODULES += $(modules_rest)

$(call expand-required-modules,product_MODULES,$(product_MODULES))

product_FILES := $(call module-installed-files, $(product_MODULES))

ifeq (0,1)

$(info product_FILES for $(TARGET_DEVICE) ($(INTERNAL_PRODUCT)):)

$(foreach p,$(product_FILES),$(info : $(p)))

$(error done)

endif

else

# We’re not doing a full build, and are probably only including

# a subset of the module makefiles. Don’t try to build any modules

# requested by the product, because we probably won’t have rules

# to build them.

product_FILES :=

endif

<!–[if !supportLists]–>15、<!–[endif]–>检查我们构建的模块是否冗余了

modules_to_check := $(foreach m,$(ALL_MODULES),$(ALL_MODULES.$(m).CHECKED))

ifneq ($(filter all,$(MAKECMDGOALS)),)

modules_to_check += $(foreach m,$(ALL_MODULES),$(ALL_MODULES.$(m).BUILT))

endif

# for easier debugging

modules_to_check := $(sort $(modules_to_check))

<!–[if !supportLists]–>16、<!–[endif]–>上面的都是配置操作，接下来就是整个项目的编译操作，确定好要生成的目标并开始编译。make默认执行droid，droid依赖于droidcore，droidcore依赖于files等等，这些依赖关系就控制着整个项目的编译流程。

.PHONY: files

files: prebuilt \

$(modules_to_install) \

$(INSTALLED_ANDROID_INFO_TXT_TARGET)

.PHONY: droidcore

droidcore: files \

systemimage \

$(INSTALLED_CHIPRAM_TARGET) \

$(INSTALLED_UBOOT_TARGET) \

$(INSTALLED_BOOTIMAGE_TARGET) \

$(INSTALLED_RECOVERYIMAGE_TARGET) \

$(INSTALLED_USERDATAIMAGE_TARGET) \

$(INSTALLED_CACHEIMAGE_TARGET) \

$(INSTALLED_PRODNVIMAGE_TARGET) \

$(INSTALLED_VENDORIMAGE_TARGET) \

$(INSTALLED_FILES_FILE)

四、加载的其他mk脚本分析

1、help.mk的分析

这个脚本功能主要是打印出编译时的一些帮助信息

.PHONY: help

help:

@echo

@echo “Common make targets:”

@echo “———————————————————————————-”

@echo “droid Default target”

@echo “clean (aka clobber) equivalent to rm -rf out/”

@echo “snod Quickly rebuild the system image from built packages”

@echo “offline-sdk-docs Generate the HTML for the developer SDK docs”

@echo “doc-comment-check-docs Check HTML doc links & validity, without generating HTML”

@echo “libandroid_runtime All the JNI framework stuff”

@echo “framework All the java framework stuff”

@echo “services The system server (Java) and friends”

@echo “help You’re reading it right now”

.PHONY: out

out:

@echo “I’m sure you’re nice and all, but no thanks.”

2、config.mk的分析

2.1、定义一些文件路径变量

SRC_DOCS:= $(TOPDIR)docs

SRC_HEADERS := \

$(TOPDIR)system/core/include \

$(TOPDIR)hardware/libhardware/include \

$(TOPDIR)hardware/libhardware_legacy/include \

$(TOPDIR)hardware/ril/include \

$(TOPDIR)libnativehelper/include \

$(TOPDIR)frameworks/native/include \

$(TOPDIR)frameworks/native/opengl/include \

$(TOPDIR)frameworks/av/include \

$(TOPDIR)frameworks/base/include

SRC_HOST_HEADERS:=$(TOPDIR)tools/include

SRC_LIBRARIES:= $(TOPDIR)libs

SRC_SERVERS:= $(TOPDIR)servers

SRC_TARGET_DIR := $(TOPDIR)build/target

SRC_API_DIR := $(TOPDIR)prebuilts/sdk/api

SRC_SYSTEM_API_DIR := $(TOPDIR)prebuilts/sdk/system-api

SRC_DROIDDOC_DIR := $(TOPDIR)build/tools/droiddoc

2.2、加载pathmap.mk脚本文件，这个文件主要定义了一些绝对路径变量，便于其他脚本调用。

include $(BUILD_SYSTEM)/pathmap.mk

2.3、定义一些重要编译命令

BUILD_COMBOS:= $(BUILD_SYSTEM)/combo

CLEAR_VARS:= $(BUILD_SYSTEM)/clear_vars.mk

BUILD_HOST_STATIC_LIBRARY:= $(BUILD_SYSTEM)/host_static_library.mk

BUILD_HOST_SHARED_LIBRARY:= $(BUILD_SYSTEM)/host_shared_library.mk

BUILD_STATIC_LIBRARY:= $(BUILD_SYSTEM)/static_library.mk

BUILD_RAW_STATIC_LIBRARY := $(BUILD_SYSTEM)/raw_static_library.mk

BUILD_SHARED_LIBRARY:= $(BUILD_SYSTEM)/shared_library.mk

BUILD_EXECUTABLE:= $(BUILD_SYSTEM)/executable.mk

BUILD_RAW_EXECUTABLE:= $(BUILD_SYSTEM)/raw_executable.mk

BUILD_HOST_EXECUTABLE:= $(BUILD_SYSTEM)/host_executable.mk

BUILD_PACKAGE:= $(BUILD_SYSTEM)/package.mk

BUILD_PHONY_PACKAGE:= $(BUILD_SYSTEM)/phony_package.mk

BUILD_HOST_PREBUILT:= $(BUILD_SYSTEM)/host_prebuilt.mk

BUILD_PREBUILT:= $(BUILD_SYSTEM)/prebuilt.mk

BUILD_MULTI_PREBUILT:= $(BUILD_SYSTEM)/multi_prebuilt.mk

BUILD_JAVA_LIBRARY:= $(BUILD_SYSTEM)/java_library.mk

BUILD_STATIC_JAVA_LIBRARY:= $(BUILD_SYSTEM)/static_java_library.mk

BUILD_HOST_JAVA_LIBRARY:= $(BUILD_SYSTEM)/host_java_library.mk

BUILD_DROIDDOC:= $(BUILD_SYSTEM)/droiddoc.mk

BUILD_COPY_HEADERS := $(BUILD_SYSTEM)/copy_headers.mk

BUILD_NATIVE_TEST := $(BUILD_SYSTEM)/native_test.mk

BUILD_HOST_NATIVE_TEST := $(BUILD_SYSTEM)/host_native_test.mk

BUILD_SHARED_TEST_LIBRARY := $(BUILD_SYSTEM)/shared_test_lib.mk

BUILD_HOST_SHARED_TEST_LIBRARY := $(BUILD_SYSTEM)/host_shared_test_lib.mk

BUILD_STATIC_TEST_LIBRARY := $(BUILD_SYSTEM)/static_test_lib.mk

BUILD_HOST_STATIC_TEST_LIBRARY := $(BUILD_SYSTEM)/host_static_test_lib.mk

BUILD_NOTICE_FILE := $(BUILD_SYSTEM)/notice_files.mk

BUILD_HOST_DALVIK_JAVA_LIBRARY := $(BUILD_SYSTEM)/host_dalvik_java_library.mk

BUILD_HOST_DALVIK_STATIC_JAVA_LIBRARY := $(BUILD_SYSTEM)/host_dalvik_static_java_library.mk

############# vendor configs ################

BUILD_THEME_PACKAGE := $(BUILD_SYSTEM_VENDOR)/themepackage.mk

BUILD_ADDON_PACKAGE := $(BUILD_PACKAGE)

APPLY_PRODUCT_REVISION:= build/vendor/product_config.mk

其中

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

2.4、打包后缀名的设置

COMMON_PACKAGE_SUFFIX := .zip

COMMON_JAVA_PACKAGE_SUFFIX := .jar

COMMON_ANDROID_PACKAGE_SUFFIX := .apk

2.5、加载一些其他mk文件

ifndef ANDROID_BUILDSPEC

ANDROID_BUILDSPEC := $(TOPDIR)buildspec.mk

endif

-include $(ANDROID_BUILDSPEC)

# —————————————————————

# Define most of the global variables. These are the ones that

# are specific to the user’s build configuration.

include $(BUILD_SYSTEM)/envsetup.mk

….

include $(BUILD_SYSTEM)/combo/select.mk

2.6、判断支持32位编译还是64位编译

ifeq (,$(TARGET_CPU_ABI_LIST))

ifeq ($(TARGET_IS_64_BIT)|$(TARGET_PREFER_32_BIT_APPS),true|true)

TARGET_CPU_ABI_LIST := $(TARGET_CPU_ABI_LIST_32_BIT) $(TARGET_CPU_ABI_LIST_64_BIT)

else

TARGET_CPU_ABI_LIST := $(TARGET_CPU_ABI_LIST_64_BIT) $(TARGET_CPU_ABI_LIST_32_BIT)

endif

2.7、加载javac.mk脚本

include $(BUILD_SYSTEM)/combo/javac.mk

2.8、设置一些命令的变量（比如aapt、aidl等）

AAPT := $(HOST_OUT_EXECUTABLES)/aapt$(HOST_EXECUTABLE_SUFFIX)

AIDL := $(HOST_OUT_EXECUTABLES)/aidl$(HOST_EXECUTABLE_SUFFIX)

PROTOC := $(HOST_OUT_EXECUTABLES)/aprotoc$(HOST_EXECUTABLE_SUFFIX)

SIGNAPK_JAR := $(HOST_OUT_JAVA_LIBRARIES)/signapk$(COMMON_JAVA_PACKAGE_SUFFIX)

MKBOOTFS := $(HOST_OUT_EXECUTABLES)/mkbootfs$(HOST_EXECUTABLE_SUFFIX)

MINIGZIP := $(HOST_OUT_EXECUTABLES)/minigzip$(HOST_EXECUTABLE_SUFFIX)

ifeq (,$(strip $(BOARD_CUSTOM_MKBOOTIMG)))

MKBOOTIMG := $(HOST_OUT_EXECUTABLES)/mkbootimg$(HOST_EXECUTABLE_SUFFIX)

else

MKBOOTIMG := $(BOARD_CUSTOM_MKBOOTIMG)

endif

MKYAFFS2 := $(HOST_OUT_EXECUTABLES)/mkyaffs2image$(HOST_EXECUTABLE_SUFFIX)

APICHECK := $(HOST_OUT_EXECUTABLES)/apicheck$(HOST_EXECUTABLE_SUFFIX)

FS_GET_STATS := $(HOST_OUT_EXECUTABLES)/fs_get_stats$(HOST_EXECUTABLE_SUFFIX)

MKEXT2IMG := $(HOST_OUT_EXECUTABLES)/genext2fs$(HOST_EXECUTABLE_SUFFIX)

MAKE_EXT4FS := $(HOST_OUT_EXECUTABLES)/make_ext4fs$(HOST_EXECUTABLE_SUFFIX)

MKEXTUSERIMG := $(HOST_OUT_EXECUTABLES)/mkuserimg.sh

MAKE_F2FS := $(HOST_OUT_EXECUTABLES)/make_f2fs$(HOST_EXECUTABLE_SUFFIX)

MKF2FSUSERIMG := $(HOST_OUT_EXECUTABLES)/mkf2fsuserimg.sh

MKEXT2BOOTIMG := external/genext2fs/mkbootimg_ext2.sh

SIMG2IMG := $(HOST_OUT_EXECUTABLES)/simg2img$(HOST_EXECUTABLE_SUFFIX)

E2FSCK := $(HOST_OUT_EXECUTABLES)/e2fsck$(HOST_EXECUTABLE_SUFFIX)

MKTARBALL := build/tools/mktarball.sh

TUNE2FS := $(HOST_OUT_EXECUTABLES)/tune2fs$(HOST_EXECUTABLE_SUFFIX)

E2FSCK := $(HOST_OUT_EXECUTABLES)/e2fsck$(HOST_EXECUTABLE_SUFFIX)

JARJAR := $(HOST_OUT_JAVA_LIBRARIES)/jarjar.jar

PROGUARD := external/proguard/bin/proguard.sh

JAVATAGS := build/tools/java-event-log-tags.py

LLVM_RS_CC := $(HOST_OUT_EXECUTABLES)/llvm-rs-cc$(HOST_EXECUTABLE_SUFFIX)

BCC_COMPAT := $(HOST_OUT_EXECUTABLES)/bcc_compat$(HOST_EXECUTABLE_SUFFIX)

LINT := prebuilts/sdk/tools/lint

RMTYPEDEFS := $(HOST_OUT_EXECUTABLES)/rmtypedefs

APPEND2SIMG := $(HOST_OUT_EXECUTABLES)/append2simg

VERITY_SIGNER := $(HOST_OUT_EXECUTABLES)/verity_signer

BUILD_VERITY_TREE := $(HOST_OUT_EXECUTABLES)/build_verity_tree

BOOT_SIGNER := $(HOST_OUT_EXECUTABLES)/boot_signer

2.9、执行shell脚本去查找jdk的tools和jar，根据系统环境的不同（OS、32位和64位）执行不同的java操作

ifeq ($(HOST_OS),darwin)

ifeq ($(LEGACY_USE_JAVA6),)

HOST_JDK_TOOLS_JAR:= $(shell $(BUILD_SYSTEM)/find-jdk-tools-jar.sh)

else

# Deliberately set to blank for Java 6 installations on MacOS. These

# versions allegedly use a non-standard directory structure.

HOST_JDK_TOOLS_JAR :=

endif

else

HOST_JDK_TOOLS_JAR:= $(shell $(BUILD_SYSTEM)/find-jdk-tools-jar.sh)

endif

ifneq ($(HOST_JDK_TOOLS_JAR),)

ifeq ($(wildcard $(HOST_JDK_TOOLS_JAR)),)

$(error Error: could not find jdk tools.jar, please check if your JDK was installed correctly)

endif

2.10、根据TARGET_BUILD_VARIANT（debug、user、userdebug）的不同，设置不同的签名

ifdef PRODUCT_DEFAULT_DEV_CERTIFICATE

DEFAULT_SYSTEM_DEV_CERTIFICATE := $(PRODUCT_DEFAULT_DEV_CERTIFICATE)

else

ifeq ($(strip $(TARGET_BUILD_VARIANT)),user)

DEFAULT_SYSTEM_DEV_CERTIFICATE := build/target/product/security/release/releasekey

BUILD_KEYS := release-keys

else

DEFAULT_SYSTEM_DEV_CERTIFICATE := build/target/product/security/testkey

endif

2.11、DEX2OAT运行的一些变量配置

DEX2OAT_TARGET_ARCH := $(TARGET_ARCH)

DEX2OAT_TARGET_CPU_VARIANT := $(TARGET_CPU_VARIANT)

DEX2OAT_TARGET_INSTRUCTION_SET_FEATURES := default

ifneq (,$(filter $(DEX2OAT_TARGET_CPU_VARIANT),cortex-a7 cortex-a15 krait denver))

DEX2OAT_TARGET_INSTRUCTION_SET_FEATURES := div

endif

ifdef TARGET_2ND_ARCH

$(TARGET_2ND_ARCH_VAR_PREFIX)DEX2OAT_TARGET_ARCH := $(TARGET_2ND_ARCH)

$(TARGET_2ND_ARCH_VAR_PREFIX)DEX2OAT_TARGET_CPU_VARIANT := $(TARGET_2ND_CPU_VARIANT)

$(TARGET_2ND_ARCH_VAR_PREFIX)DEX2OAT_TARGET_INSTRUCTION_SET_FEATURES := default

ifneq (,$(filter $($(TARGET_2ND_ARCH_VAR_PREFIX)DEX2OAT_TARGET_CPU_VARIANT),cortex-a7 cortex-a15 krait denver))

$(TARGET_2ND_ARCH_VAR_PREFIX)DEX2OAT_TARGET_INSTRUCTION_SET_FEATURES := div

endif

3、envsetup.mk的分析

3.1、加载version_defaults.mk脚本

include $(BUILD_SYSTEM)/version_defaults.mk

3.2、设置一些变量的值

# —————————————————————

# If you update the build system such that the environment setup

# or buildspec.mk need to be updated, increment this number, and

# people who haven’t re-run those will have to do so before they

# can build. Make sure to also update the corresponding value in

# buildspec.mk.default and envsetup.sh.

CORRECT_BUILD_ENV_SEQUENCE_NUMBER := 10

# —————————————————————

# The product defaults to generic on hardware

# NOTE: This will be overridden in product_config.mk if make

# was invoked with a PRODUCT-xxx-yyy goal.

ifeq ($(TARGET_PRODUCT),)

TARGET_PRODUCT := full

endif

# the variant — the set of files that are included for a build

ifeq ($(strip $(TARGET_BUILD_VARIANT)),)

TARGET_BUILD_VARIANT := eng

endif

3.3、根据shell命令uname -sm执行结果，也就是当前编译系统的环境，来设置一些变量的值，我这边虚拟机运行的结果是：Linux x86_64

UNAME := $(shell uname -sm)

# HOST_OS

ifneq (,$(findstring Linux,$(UNAME)))

HOST_OS := linux

endif

ifneq (,$(findstring Darwin,$(UNAME)))

HOST_OS := darwin

endif

ifneq (,$(findstring Macintosh,$(UNAME)))

HOST_OS := darwin

endif

ifneq (,$(findstring CYGWIN,$(UNAME)))

HOST_OS := windows

endif

# BUILD_OS is the real host doing the build.

BUILD_OS := $(HOST_OS)

# Under Linux, if USE_MINGW is set, we change HOST_OS to Windows to build the

# Windows SDK. Only a subset of tools and SDK will manage to build properly.

ifeq ($(HOST_OS),linux)

ifneq ($(USE_MINGW),)

HOST_OS := windows

endif

ifeq ($(HOST_OS),)

$(error Unable to determine HOST_OS from uname -sm: $(UNAME)!)

endif

# TODO: Replace BUILD_HOST_64bit with a flag that forces 32-bit build,

# after we default to 64-bit host build.

ifeq (,$(BUILD_HOST_64bit))

# Default to 32-bit-by-default multilib host build.

HOST_PREFER_32_BIT := true

endif

# HOST_ARCH

ifneq (,$(findstring x86_64,$(UNAME)))

HOST_ARCH := x86_64

HOST_2ND_ARCH := x86

HOST_IS_64_BIT := true

endif

ifeq ($(HOST_PREFER_32_BIT),true)

SDK_HOST_ARCH := x86

else

SDK_HOST_ARCH := $(HOST_ARCH)

endif

BUILD_ARCH := $(HOST_ARCH)

BUILD_2ND_ARCH := $(HOST_2ND_ARCH)

ifeq ($(HOST_ARCH),)

$(error Unable to determine HOST_ARCH from uname -sm: $(UNAME)!)

endif

# the host build defaults to release, and it must be release or debug

ifeq ($(HOST_BUILD_TYPE),)

HOST_BUILD_TYPE := release

endif

ifneq ($(HOST_BUILD_TYPE),release)

ifneq ($(HOST_BUILD_TYPE),debug)

$(error HOST_BUILD_TYPE must be either release or debug, not ‘$(HOST_BUILD_TYPE)’)

endif

# We don’t want to move all the prebuilt host tools to a $(HOST_OS)-x86_64 dir.

HOST_PREBUILT_ARCH := x86

# This is the standard way to name a directory containing prebuilt host

# objects. E.g., prebuilt/$(HOST_PREBUILT_TAG)/cc

ifeq ($(HOST_OS),windows)

HOST_PREBUILT_TAG := windows

else

HOST_PREBUILT_TAG := $(HOST_OS)-$(HOST_PREBUILT_ARCH)

endif

3.4、设置输出目录名称

TARGET_COPY_OUT_SYSTEM := system

TARGET_COPY_OUT_DATA := data

TARGET_COPY_OUT_OEM := oem

TARGET_COPY_OUT_ROOT := root

TARGET_COPY_OUT_RECOVERY := recovery

3.5、加载product_config.mk脚本

include $(BUILD_SYSTEM)/product_config.mk

3.6、根据TARGET_DEVICE的值寻找BoardConfig.mk脚本并加载

board_config_mk := \

$(strip $(wildcard \

$(SRC_TARGET_DIR)/board/$(TARGET_DEVICE)/BoardConfig.mk \

$(shell test -d device && find device -maxdepth 4 -path ‘*/$(TARGET_DEVICE)/BoardConfig.mk’) \

$(shell test -d vendor && find vendor -maxdepth 4 -path ‘*/$(TARGET_DEVICE)/BoardConfig.mk’) \

))

ifeq ($(board_config_mk),)

$(error No config file found for TARGET_DEVICE $(TARGET_DEVICE))

endif

ifneq ($(words $(board_config_mk)),1)

$(error Multiple board config files for TARGET_DEVICE $(TARGET_DEVICE): $(board_config_mk))

endif

include $(board_config_mk)

3.7、根据系统环境设置输出目录的路径

TARGET_OS := linux

# TARGET_ARCH should be set by BoardConfig.mk and will be checked later

ifneq ($(filter %64,$(TARGET_ARCH)),)

TARGET_IS_64_BIT := true

endif

# the target build type defaults to release

ifneq ($(TARGET_BUILD_TYPE),debug)

TARGET_BUILD_TYPE := release

endif

# —————————————————————

# figure out the output directories

ifeq (,$(strip $(OUT_DIR)))

ifeq (,$(strip $(OUT_DIR_COMMON_BASE)))

OUT_DIR := $(TOPDIR)out

else

OUT_DIR := $(OUT_DIR_COMMON_BASE)/$(notdir $(PWD))

endif

DEBUG_OUT_DIR := $(OUT_DIR)/debug

# Move the host or target under the debug/ directory

# if necessary.

TARGET_OUT_ROOT_release := $(OUT_DIR)/target

TARGET_OUT_ROOT_debug := $(DEBUG_OUT_DIR)/target

TARGET_OUT_ROOT := $(TARGET_OUT_ROOT_$(TARGET_BUILD_TYPE))

HOST_OUT_ROOT_release := $(OUT_DIR)/host

HOST_OUT_ROOT_debug := $(DEBUG_OUT_DIR)/host

HOST_OUT_ROOT := $(HOST_OUT_ROOT_$(HOST_BUILD_TYPE))

<!–[if !supportLists]–>

4、

<!–[endif]–>

product_config.mk分析

4.1、定义函数find-copy-subdir-files，执行shell命令查找子目录下指定文件用于PRODUCT_COPY_FILES和PRODUCT_SDK_ADDON_COPY_FILES

###########################################################

## List all of the files in a subdirectory in a format

## suitable for PRODUCT_COPY_FILES and

## PRODUCT_SDK_ADDON_COPY_FILES

## $(1): Glob to match file name

## $(2): Source directory

## $(3): Target base directory

###########################################################

define find-copy-subdir-files

$(shell find $(2) -name “$(1)” | $(SED_EXTENDED) “s:($(2)/?(.*)):\\1\\:$(3)/\\2:” | sed “s://:/:g”)

endef

4.2、确定TARGET_BUILD_VARIANT和TARGET_PRODUCT的值

# These are the valid values of TARGET_BUILD_VARIANT. Also, if anything else is passed

# as the variant in the PRODUCT-$TARGET_BUILD_PRODUCT-$TARGET_BUILD_VARIANT form,

# it will be treated as a goal, and the eng variant will be used.

INTERNAL_VALID_VARIANTS := user userdebug eng

# —————————————————————

# Provide “PRODUCT-<prodname>-<goal>” targets, which lets you build

# a particular configuration without needing to set up the environment.

product_goals := $(strip $(filter PRODUCT-%,$(MAKECMDGOALS)))

ifdef product_goals

# Scrape the product and build names out of the goal,

# which should be of the form PRODUCT-<productname>-<buildname>.

ifneq ($(words $(product_goals)),1)

$(error Only one PRODUCT-* goal may be specified; saw “$(product_goals)”)

endif

goal_name := $(product_goals)

product_goals := $(patsubst PRODUCT-%,%,$(product_goals))

product_goals := $(subst -, ,$(product_goals))

ifneq ($(words $(product_goals)),2)

$(error Bad PRODUCT-* goal “$(goal_name)”)

endif

# The product they want

TARGET_PRODUCT := $(word 1,$(product_goals))

# The variant they want

TARGET_BUILD_VARIANT := $(word 2,$(product_goals))

ifeq ($(TARGET_BUILD_VARIANT),tests)

$(error “tests” has been deprecated as a build variant. Use it as a build goal instead.)

endif

# The build server wants to do make PRODUCT-dream-installclean

# which really means TARGET_PRODUCT=dream make installclean.

ifneq ($(filter-out $(INTERNAL_VALID_VARIANTS),$(TARGET_BUILD_VARIANT)),)

MAKECMDGOALS := $(MAKECMDGOALS) $(TARGET_BUILD_VARIANT)

TARGET_BUILD_VARIANT := eng

default_goal_substitution :=

else

default_goal_substitution := $(DEFAULT_GOAL)

endif

4.3、加载一些其他的mk脚本

include $(BUILD_SYSTEM)/node_fns.mk

include $(BUILD_SYSTEM)/product.mk

include $(BUILD_SYSTEM)/device.mk

4.4、搜索所有的AndroidProducts.mk文件，找到当前产品的配置文件

ifneq ($(strip $(TARGET_BUILD_APPS)),)

# An unbundled app build needs only the core product makefiles.

all_product_configs := $(call get-product-makefiles,\

$(SRC_TARGET_DIR)/product/AndroidProducts.mk)

else

# Read in all of the product definitions specified by the AndroidProducts.mk

# files in the tree.

all_product_configs := $(get-all-product-makefiles)

endif

# Find the product config makefile for the current product.

# all_product_configs consists items like:

# <product_name>:<path_to_the_product_makefile>

# or just <path_to_the_product_makefile> in case the product name is the

# same as the base filename of the product config makefile.

current_product_makefile :=

all_product_makefiles :=

$(foreach f, $(all_product_configs),\

$(eval _cpm_words := $(subst :,$(space),$(f)))\

$(eval _cpm_word1 := $(word 1,$(_cpm_words)))\

$(eval _cpm_word2 := $(word 2,$(_cpm_words)))\

$(if $(_cpm_word2),\

$(eval all_product_makefiles += $(_cpm_word2))\

$(if $(filter $(TARGET_PRODUCT),$(_cpm_word1)),\

$(eval current_product_makefile += $(_cpm_word2)),),\

$(eval all_product_makefiles += $(f))\

$(if $(filter $(TARGET_PRODUCT),$(basename $(notdir $(f)))),\

$(eval current_product_makefile += $(f)),)))

_cpm_words :=

_cpm_word1 :=

_cpm_word2 :=

current_product_makefile := $(strip $(current_product_makefile))

all_product_makefiles := $(strip $(all_product_makefiles))

4.5、调用clear-var-list函数去清除一些变量，并设置产品的运行时态product_runtimes

$(call clear-var-list, $(_product_var_list))

# Set PRODUCT_RUNTIMES, allowing buildspec to override using OVERRIDE_RUNTIMES

product_runtimes := $(sort $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_RUNTIMES))

ifneq ($(OVERRIDE_RUNTIMES),)

$(info Overriding PRODUCT_RUNTIMES=$(product_runtimes) with $(OVERRIDE_RUNTIMES))

product_runtimes := $(OVERRIDE_RUNTIMES)

endif

$(foreach runtime, $(product_runtimes), $(eval include $(SRC_TARGET_DIR)/product/$(runtime).mk))

$(foreach v, $(_product_var_list), $(if $($(v)),\

$(eval PRODUCTS.$(INTERNAL_PRODUCT).$(v) += $(sort $($(v))))))

$(call clear-var-list, $(_product_var_list))

# Now we can assign to PRODUCT_RUNTIMES

PRODUCT_RUNTIMES := $(product_runtimes)

product_runtimes :=

PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_PROPERTY_OVERRIDES += persist.sys.dalvik.vm.lib.2=$(DALVIK_VM_LIB)

ifeq ($(words $(PRODUCT_RUNTIMES)),1)

# If we only have one runtime, we can strip classes.dex by default during dex_preopt

DEX_PREOPT_DEFAULT := true

else

# If we have more than one, we leave the classes.dex alone for post-boot analysis

DEX_PREOPT_DEFAULT := nostripping

endif

4.6、获取BOOTCLASSPATH中的所有jar文件

# A list of module names of BOOTCLASSPATH (jar files)

PRODUCT_BOOT_JARS := $(strip $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_BOOT_JARS))

PRODUCT_SYSTEM_SERVER_JARS := $(strip $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SYSTEM_SERVER_JARS))

4.7、设置TARGET_DEVICE和PRODUCT_LOCALES的值

# Find the device that this product maps to.

TARGET_DEVICE := $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_DEVICE)

# Figure out which resoure configuration options to use for this

# product.

PRODUCT_LOCALES := $(strip $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_LOCALES))

# TODO: also keep track of things like “port”, “land” in product files.

# If CUSTOM_LOCALES contains any locales not already included

# in PRODUCT_LOCALES, add them to PRODUCT_LOCALES.

extra_locales := $(filter-out $(PRODUCT_LOCALES),$(CUSTOM_LOCALES))

ifneq (,$(extra_locales))

ifneq ($(CALLED_FROM_SETUP),true)

# Don’t spam stdout, because envsetup.sh may be scraping values from it.

$(info Adding CUSTOM_LOCALES [$(extra_locales)] to PRODUCT_LOCALES [$(PRODUCT_LOCALES)])

endif

PRODUCT_LOCALES += $(extra_locales)

extra_locales :=

endif

4.8、配置aapt的相关属性

# Add PRODUCT_LOCALES to PRODUCT_AAPT_CONFIG

PRODUCT_AAPT_CONFIG := $(strip $(PRODUCT_LOCALES) $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_AAPT_CONFIG))

PRODUCT_AAPT_PREF_CONFIG := $(strip $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_AAPT_PREF_CONFIG))

PRODUCT_AAPT_PREBUILT_DPI := $(strip $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_AAPT_PREBUILT_DPI))

# Keep a copy of the space-separated config

PRODUCT_AAPT_CONFIG_SP := $(PRODUCT_AAPT_CONFIG)

# Convert spaces to commas.

PRODUCT_AAPT_CONFIG := \

$(subst $(space),$(comma),$(strip $(PRODUCT_AAPT_CONFIG)))

# product-scoped aapt flags

PRODUCT_AAPT_FLAGS :=

ifneq ($(filter en_XA ar_XB,$(PRODUCT_LOCALES)),)

# Force generating resources for pseudo-locales.

PRODUCT_AAPT_FLAGS += –pseudo-localize

endif

4.9、设置一些变量的值

PRODUCT_BRAND := $(strip $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_BRAND))

PRODUCT_MODEL := $(strip $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_MODEL))

ifndef PRODUCT_MODEL

PRODUCT_MODEL := $(strip $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_NAME))

endif

PRODUCT_MANUFACTURER := \

$(strip $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_MANUFACTURER))

ifndef PRODUCT_MANUFACTURER

PRODUCT_MANUFACTURER := unknown

endif

ifeq ($(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_CHARACTERISTICS),)

TARGET_AAPT_CHARACTERISTICS := default

else

TARGET_AAPT_CHARACTERISTICS := $(strip $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_CHARACTERISTICS))

endif

PRODUCT_DEFAULT_WIFI_CHANNELS := \

$(strip $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_DEFAULT_WIFI_CHANNELS))

PRODUCT_DEFAULT_DEV_CERTIFICATE := \

$(strip $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_DEFAULT_DEV_CERTIFICATE))

ifdef PRODUCT_DEFAULT_DEV_CERTIFICATE

ifneq (1,$(words $(PRODUCT_DEFAULT_DEV_CERTIFICATE)))

$(error PRODUCT_DEFAULT_DEV_CERTIFICATE=’$(PRODUCT_DEFAULT_DEV_CERTIFICATE)’, \

only 1 certificate is allowed.)

endif

<!–[if !supportLists]–>

5、

<!–[endif]–>

definitions.mk分析

这个脚本主要是定义了很多函数，相当于一个函数库用于编译所需

define print-vars

$(foreach var,$(1), \

$(info $(var):) \

$(foreach word,$($(var)), \

$(info $(space)$(space)$(word)) \

) \

)

endef

define true-or-empty

$(filter true, $(1))

endef

define my-dir

$(strip \

$(eval LOCAL_MODULE_MAKEFILE := $$(lastword $$(MAKEFILE_LIST))) \

$(if $(filter $(BUILD_SYSTEM)/% $(OUT_DIR)/%,$(LOCAL_MODULE_MAKEFILE)), \

$(error my-dir must be called before including any other makefile.) \

, \

$(patsubst %/,%,$(dir $(LOCAL_MODULE_MAKEFILE))) \

) \

)

endef

五、Android.mk分析

Android.mk是用来向编译系统描述你的源代码，也就是告诉编译系统你的源代码需要编译成什么样。你可以在一个Android.mk文件中定义一个或者多个模块，模块的类型包括：

1）APK程序，一般的Android程序，编译打包生成apk文件

2）Java库，java类库，编译打包生成jar文件

3) C\C++应用程序，可执行的C\C++应用程序

4）C\C++静态库，编译生成C\C++静态库，并打包成.a文件

5）C\C++共享库，编译生成共享库（动态链接库），并打包成.so文件，有且只有共享库才能被安装/复制到您的应用软件（APK）包中。

下面是一个Android.mk的例子：

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE := settings_talpa

LOCAL_MODULE_TAGS := optional

LOCAL_MODULE_CLASS := APPS

LOCAL_MODULE_SUFFIX := .apk

LOCAL_SRC_FILES := Settings.apk

LOCAL_MODULE_PATH := $(TARGET_OUT_APPS_PRIVILEGED)

LOCAL_CERTIFICATE := platform

LOCAL_OVERRIDES_PACKAGES := Settings

include $(BUILD_PREBUILT)

接下来根据这个例子来解释每一行代码

<!–[if !supportLists]–>1、<!–[endif]–>LOCAL_PATH := $(call my-dir)

每个Android.mk必须定义LOCAL_PATH这个变量，它用于在开发树中查找源文件。my-dir是一个函数名，由编译系统提供，用于返回当前Android.mk的目录路径。$(call my-dir)表示的就是去调用my-dir这个函数

2、include $(CLEAR_VARS)

CLEAR_VARS是由编译系统提供的变量，config.mk文件中能找到其定义，前面也提到过，它的值是$(BUILD_SYSTEM)/clear_vars.mk，这句代码表示去加载并执行这个mk脚本，清理掉local_xxx这样的一些变量。

<!–[if !supportLists]–>3、<!–[endif]–>LOCAL_MODULE := settings_talpa

LOCAL_MODULE也是必须定义的变量，表示模块的名字，这个名字必须唯一且不包含空格。编译系统会自动添加适当的前缀和后缀。

4、LOCAL_MODULE_TAGS := optional

LOCAL_MODULE_TAGS表示当前模块在哪种模式下编译，模式包含user eng tests optional。

user: 指该模块只在user版本下才编译

eng: 指该模块只在eng版本下才编译

tests: 指该模块只在tests版本下才编译

optional:指该模块在所有版本下都编译

5、LOCAL_MODULE_CLASS := APPS

LOCAL_MODULE_CLASS 指定模块的文件类型，apk文件用APPS, 并且会检查是否是apk文件，动态库so文件用SHARED_LIBRARIES ，bin文件用EXECUTABLES，其他文件用ETC

6、LOCAL_MODULE_SUFFIX := .apk

LOCAL_MODULE_SUFFIX指定模块的后缀

<!–[if !supportLists]–>7、<!–[endif]–>LOCAL_SRC_FILES

LOCAL_SRC_FILES指定需要打包进模块的文件

<!–[if !supportLists]–>8、<!–[endif]–>LOCAL_MODULE_PATH

LOCAL_MODULE_PATH指定模块的安装路径

$(TARGET_OUT_APPS_PRIVILEGED):system/priv-app/

$(TARGET_OUT_APPS):system/app/

9、LOCAL_CERTIFICATE := platform

LOCAL_CERTIFICATE指定模块的签名key值，包含media、shared、platform、

PRESIGNED

（表示已经签过名，不需要签名）

<!–[if !supportLists]–>10、<!–[endif]–>LOCAL_OVERRIDES_PACKAGES := Settings

LOCAL_OVERRIDES_PACKAGES表示当前模块需要覆盖系统原有的哪个模块名

11、include $(BUILD_PREBUILT)

这句代码同样也是加载其他的脚本

BUILD_PACKAGE

：指向build/core/package.mk，用来编译APK文件。

BUILD_JAVA_LIBRARY

：指向build/core/java_library.mk，用来编译Java库文件。

BUILD_STATIC_JAVA_LIBRARY

：指向build/core/tatic_java_library.mk，用来编译Java静态库文件。

BUILD_STATIC_LIBRARY

：指向build/core/static_library.mk，用来编译静态库文件。也就是.a文件。

BUILD_EXECUTABLE

：指向build/core/executable.mk，用来编译可执行文件。

BUILD_PREBUILT

：指向build/core/prebuilt.mk。用来编译已经预编译好的第三方库文件，实际上是将这些预编译好的第三方库文件拷贝到合适的位置去，以便可以让其它模块引用。

六、Android源码各级目录分析

我们知道Android平台分为四层架构，分别是应用程序层、应用框架层、运行库层和Linux内核层，这四层架构和Android源码目录的对应关系如下：

<!–[if !supportLists]–>

1、

<!–[endif]–>

应用程序层对应的是packages/apps

<!–[if !supportLists]–>

2、

<!–[endif]–>

应用框架层对应的是frameworks

<!–[if !supportLists]–>

3、

<!–[endif]–>

运行库层对应的是libcore、dalvik

<!–[if !supportLists]–>

4、

<!–[endif]–>

Linux内核层对应的是kernel

下面详细介绍Android源码的目录结构：

B

ionic：包含一些C语言库，比如内核层的一些头文件、时区的相关代码等等

B

ootable：启动引导的相关代码，包含bootloader、ota、recovery等等

B

uild：存放系统编译规则以及编译所需的基础包和相关工具

C

ts：

Android兼容性测试套件标准

D

alvik：dalvik虚拟机的相关代码

D

evelopment：应用程序开发所需的一些例子源码和相关工具

E

xternal：Android的一些开源模块，比如加密、xml解析、压缩、数据库等等

F

rameworks：Android的核心框架（Java和C++语言），比如WiFi、蓝牙、通讯等等

H

ardware：

部分厂家开源的硬解适配层HAL代码

P

ackages：Android应用程序包，比如浏览器、计算器、相机、多媒体应用等等

P

rebuilt：

x86和arm架构下预编译的一些资源

S

dk：Android的SDK和模拟器

S

ystem：

底层文件系统库、应用及组件

V

endor：厂商定制代码

K

ernel：Linux内核相关代码和脚本

O

ut：系统编译输出目录，包含相关基础包以及相关镜像文件

D

evice：产品的相关描述文件（与编译系统有关）

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原文链接：https://blog.csdn.net/yao891203/article/details/84803372

Android编译系统过程研究

一、bulid/envsetup.sh脚本分析

二、lunch命令

<!–[if !supportLists]–>三、<!–[endif]–>make命令

四、加载的其他mk脚本分析

1、help.mk的分析

2、config.mk的分析

3、envsetup.mk的分析

<!–[if !supportLists]–> 4、 <!–[endif]–> product_config.mk分析

<!–[if !supportLists]–> 5、 <!–[endif]–> definitions.mk分析

五、Android.mk分析

六、Android源码各级目录分析

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<!–[if !supportLists]–>

4、

<!–[endif]–>

product_config.mk分析

<!–[if !supportLists]–>

5、

<!–[endif]–>

definitions.mk分析