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：
[html] 1 ### DO NOT EDIT THIS FILE ###
2 include build/core/main.mk
3 ### DO NOT EDIT THIS FILE ###
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
在main.mk里，定义了变量TOPDIR，TOP为当前目录，BUILD_SYSTEM为build/core目录。
在49行，包含了build/core/config.mk文件。
后面的代码是check环境 变量，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。这儿不是我们的重点，不再多说。
2. build/core/config.mk
该文件被main.mk包含。
定义了以下环境变量：
[plain] 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
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
[plain] .....然后定义了下面几个重要的编译命令
.....然后定义了下面几个重要的编译命令[plain] 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
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
[plain] 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 :=
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 $(board_config_mk)))
131 board_config_mk :=
112行又包含了另外一个重要的mk文件envsetup.mk，我们来看一下。
3. envsetup.mk
[plain] 25 ifeq ($(TARGET_PRODUCT),) #判断TARGET_PRODUCT是否为空，
26 ifeq ($(TARGET_SIMULATOR),true)
27 TARGET_PRODUCT := sim
28 else
29 TARGET_PRODUCT := generic
30 endif
31 endif
25 ifeq ($(TARGET_PRODUCT),) #判断TARGET_PRODUCT是否为空，
26 ifeq ($(TARGET_SIMULATOR),true)
27 TARGET_PRODUCT := sim
28 else
29 TARGET_PRODUCT := generic
30 endif
31 endif
第25行，判断TARGET_PRODUCT是否为空，根据上一节分析可知，TARGET_PRODUCT=fs100
[plain] 34 # the variant -- the set of files that are included for a build
35 ifeq ($(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 $(BUILD_SYSTEM)/product_config.mk
34 # the variant -- the set of files that are included for a build
35 ifeq ($(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 $(BUILD_SYSTEM)/product_config.mk在41行又包含了product_config.mk文件，等会我们再分析它，先看下面的
[plain] 148 # ---------------------------------------------------------------
149 # figure out the output directories
150
151 ifeq (,$(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 := $(TARGET_INSTALLER_OUT)/root/system
148 # ---------------------------------------------------------------
149 # figure out the output directories
150
151 ifeq (,$(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：
[plain] 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
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
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
[plain] 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 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，调用函数import-products, $(get-all-product-makefiles)，这儿我们看上面的注释：
Read in all of the product definitions specified by the AndroidProducts.mk files in the tree.
TODO: when we start allowing direct pointers to product files, guarantee that they're in this list.
意思是说：读取指定的目录下所有的AndrodProducts.mk文件中定义的产品信息
其实get-all-product-makefiles返回所有的产品文件xxx.mk
import-products函数去验证这些产品配置文件是否都包含有必须的配置信息，细节后面分析。
173行调用了resolve-short-product-name函数，它将返回TARGET_PRODUCT产品的配置文件目录，并赋给INTERNAL_PRODUCT
也就是说：
INTERNAL_PRODUCT = vendor/farsight/products/fs100.mk
TARGET_DEVICE = fs100
如果调试看其结果，可以在167行，将#$(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：
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
[plain] 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
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：
[plain] vendor/sample/products/AndroidProduct.mk
vendor/sample/products/AndroidProduct.mk其内容如下：
[plain] 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
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里面只定义了一个产品配置文件，即当前目录下的sample_addon.mk：
[plain] 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
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：
[plain] PRODUCT_MAKEFILES := $(LOCAL_DIR)/fs100.mk
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
[plain] 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