通過(guò)上篇文章Android編譯過(guò)程詳解（一），我們分析了編譯android時(shí)source build/envsetup.sh和lunch命令，在執(zhí)行完上述兩個(gè)命令后， 我們就可以進(jìn)行編譯android了。
1、 make
執(zhí)行make命令的結(jié)果就是去執(zhí)行當(dāng)前目錄下的Makefile文件，我們來(lái)看下它的內(nèi)容：
1 ### DO NOT EDIT THIS FILE ###
2 include build/core/main.mk
3 ### DO NOT EDIT THIS FILE ###
呵呵，看到上面 的內(nèi)容，我們都會(huì)笑，這是我見(jiàn)過(guò)簡(jiǎn)單的Makefile了，我們?cè)倏聪耣uild/core/main.mk
在main.mk里，定義了變量TOPDIR，TOP為當(dāng)前目錄，BUILD_SYSTEM為build/core目錄。
在49行，包含了build/core/config.mk文件。
后面的代碼是check環(huán)境 變量，所有的Makefile都通過(guò)build/core/main.mk這個(gè)文件組織在一起，它定義了一個(gè)默認(rèn)goals：droid，當(dāng)我們?cè)赥OP目錄下，敲Make實(shí)際上就等同于我們執(zhí)行make droid。當(dāng)Make include所有的文件，完成對(duì)所有make我文件的解析以后就會(huì)尋找生成droid的規(guī)則，依次生成它的依賴(lài)，直到所有滿(mǎn)足的模塊被編譯好，然后使用相應(yīng)的工具打包成相應(yīng)的img。這兒不是我們的重點(diǎn)，不再多說(shuō)。
2、 build/core/config.mk
該文件被main.mk包含。
定義了以下環(huán)境變量：
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
.....然后定義了下面幾個(gè)重要的編譯命令 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
上述命令變量其實(shí)是對(duì)應(yīng)的mk文件名，所有的Android.mk文件里基本上都包含上述命令變量，如：
CLEAR_VARS：用來(lái)清除之前定義的環(huán)境變量
BUILD_SHARED_LIBRARY：用來(lái)指定編譯動(dòng)態(tài)庫(kù)過(guò)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 $(board_config_mk)))
131 board_config_mk :=
112行又包含了另外一個(gè)重要的mk文件envsetup.mk，我們來(lái)看一下。
3、envsetup.mk
25 ifeq ($(TARGET_PRODUCT),) #判斷TARGET_PRODUCT是否為空，
26 ifeq ($(TARGET_SIMULATOR),true)
27 TARGET_PRODUCT := sim
28 else
29 TARGET_PRODUCT := generic
30 endif
31 endif
第25行，判斷TARGET_PRODUCT是否為空，根據(jù)上一節(jié)分析可知，TARGET_PRODUCT=fs100
34 # the variant -- the set of files that are included for a build
35 ifeq ($(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 $(BUILD_SYSTEM)/product_config.mk
在41行又包含了product_config.mk文件，等會(huì)我們?cè)俜治鏊�，先看下面�?/p>
148 # ---------------------------------------------------------------
149 # figure out the output directories
150
151 ifeq (,$(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
上面的代碼是指定了目標(biāo)輸出代碼的位置和主機(jī)輸出代碼的位置，重要的幾個(gè)如下：
PRODUCT_OUT = 這個(gè)的結(jié)果要根據(jù)product_config.mk文件內(nèi)容來(lái)決定，其實(shí)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
總結(jié)下：
envsetup.mk文件主要包含了product_config.mk文件，然后指定了編譯時(shí)要輸出的所有文件的OUT目錄。
4、 build/core/product_config.mk
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)157行，我靠，又包含了product.mk文件
165行，調(diào)用函數(shù)import-products, $(get-all-product-makefiles)，這兒我們看上面的注釋?zhuān)?/p>
Read in all of the product definitions specified by the AndroidProducts.mk files in the tree.
TODO: when we start allowing direct pointers to product files, guarantee that they're in this list.
意思是說(shuō)：讀取指定的目錄下所有的AndrodProducts.mk文件中定義的產(chǎn)品信息
其實(shí)get-all-product-makefiles返回所有的產(chǎn)品文件xxx.mk
import-products函數(shù)去驗(yàn)證這些產(chǎn)品配置文件是否都包含有必須的配置信息，細(xì)節(jié)后面分析。
173行調(diào)用了resolve-short-product-name函數(shù)，它將返回TARGET_PRODUCT產(chǎn)品的配置文件目錄，并賦給INTERNAL_PRODUCT
也就是說(shuō)：
INTERNAL_PRODUCT = vendor/farsight/products/fs100.mk
TARGET_DEVICE = fs100
如果調(diào)試看其結(jié)果，可以在167行，將#$(dump-product)取消注釋
然后在175行添加： $(info $(INTERNAL_PRODUCT))
在178行添加： $(info $(TARGET_DEVICE ))，查看調(diào)試結(jié)果。
總結(jié)一下：
product_config.mk主要讀取vendor目錄下不同廠商自己定義的AndrodProducts.mk文件，從該文件里取得所有產(chǎn)品的配置文件，然后再根據(jù)lunch選擇的編譯項(xiàng)TARGET_PRODUCT，找到與之對(duì)應(yīng)的配置文件，然后設(shè)置TARGET_DEVICE變量，用于后續(xù)編譯。
5、 build/core/product.mk
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 <strong>_find-android-products-files</strong>
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 <strong>get-all-product-makefiles</strong>
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通過(guò)注釋可知，本文件中主要是一些用來(lái)處理AndroidProduct.mk的函數(shù)
_find-android-products-files:
用來(lái)獲得vendor目錄下，所有名字為AndroidProduct.mk的文件列表。
get-all-product-makefiles：
用來(lái)獲得所有AndroidProduct.mk文件里定義的PRODUCT_MAKEFILES的值（其實(shí)是產(chǎn)品文件路徑名）。
在vendor目錄下，每個(gè)公司目錄下都會(huì)存在一個(gè)AndroidProduct.mk文件，這個(gè)文件是用來(lái)定義這個(gè)公司的產(chǎn)品列表，每個(gè)產(chǎn)品用<product_name>.mk來(lái)表示， 如Android給的示例：
vendor/sample/products/AndroidProduct.mk。其內(nèi)容如下：
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里面只定義了一個(gè)產(chǎn)品配置文件，即當(dāng)前目錄下的sample_addon.mk：
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
上述文件里定義了產(chǎn)品相關(guān)個(gè)性化信息，如，PRODUCT_PACKAGES表示要在當(dāng)前產(chǎn)品里添加一些安裝包。由此可見(jiàn)，get-all-product-makefiles函數(shù)，其實(shí)就是返回了當(dāng)前公司里全部的產(chǎn)品對(duì)應(yīng)的mk文件列表。
總結(jié)：
如果用戶(hù)想個(gè)性定制自己的產(chǎn)品，應(yīng)該有以下流程，包含上一節(jié)內(nèi)容：
1. 創(chuàng)建公司目錄
#mkdir vendor/farsight
2. 創(chuàng)建一個(gè)vendorsetup.sh文件，將當(dāng)前產(chǎn)品編譯項(xiàng)添加到lunch里，讓lunch能找到用戶(hù)個(gè)性定制編譯項(xiàng)
#echo "add_lunch_combo fs100-eng" > vendor/farsight/vendorsetup.sh
3. 仿著Android示例代碼，在公司目錄下創(chuàng)建products目錄
#mkdir -p vendor/farsight/products
4. 仿著Android示例代碼，在products目錄下創(chuàng)建兩個(gè)mk文件
#touch vendor/farsight/products/AndroidProduct.mk vendor/farsight/products/fs100.mk
在AndroidProduct.mk里添加如下內(nèi)容：
PRODUCT_MAKEFILES := $(LOCAL_DIR)/fs100.mk表示只有一個(gè)產(chǎn)品fs100，它對(duì)應(yīng)的配置文件在當(dāng)前目錄下的fs100.mk。
5.在產(chǎn)品配置文件里添加基本信息
1
2 PRODUCT_PACKAGES := \
3 IM \
4 VoiceDialer
5
6 $(call inherit-product, build/target/product/generic.mk) ##從某一默認(rèn)配置開(kāi)始派生余下內(nèi)容參考派生起點(diǎn)
7
8 # Overrides
9 PRODUCT_MANUFACTURER := farsight
10 PRODUCT_NAME := fs100
11 PRODUCT_DEVICE := fs100