Android编译过程详解（三）

前面两节讲解了自定义Android编译项和创建Product产品配置文件，除了编译和定义产品相关环境变量外，还需要定义Board相关环境变量。

1. build/core/config.mk

[plain] <pre name="code" class="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 :=
<pre name="code" class="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 :=

上述代码在上一节已经见到过，只是分析了112行的envsetup.mk，根据上一节内容可知，envsetup.mk设置了很多OUT变量，最终在build/core/product_config.mk文件里，设置了TARGET_DEVICE = fs100。

我们从114行继续分析。

从114~117行解释大意可知：

Board相关配置文件会存在于$(SRC_TARGET_DIR)/board/$(TARGET_DEVICE)/或vendor/*/$(TARGET_DEVICE)/目录中，一个Vendor厂商只能有一个对应的Board配置文件。

118行定义board_config_mk变量：

$(wildcard xxx)函数就是找到与xxx的匹配项放到空格列表里，前面定义TARGET_DEVICE变量 = fs100，所以$(SRC_TARGET_DIR)/board/fs100/BoardConfig.mk不存在，必须要存在vendor/*/fs100/BoardConfig.mk文件来定义开发板配置信息。

129行，通过include将vendor/*/fs100/BoardConfig.mk包含进来，

130行，TARGET_DEVICE_DIR为board_config_mk的路径，即：vendor/*/fs100

总结：

一个vendor厂商必须要有一个对应的Board配置文件，即：vendor/*/fs100/BoardConfig.mk

定义了TARGET_DEVICE_DIR变量，为board_config_mk的路径，即：vendor/*/fs100

指定board 相关特性,一定要包含:
TARGET_CPU_ABI := armeabi/...
其他属性参见其他board样例.(build/target/board/XXX

2. build/core/main.mk

[plain] 141 # Bring in standard build system definitions.
142 include $(BUILD_SYSTEM)/definitions.mk
...
347 ifeq ($(SDK_ONLY),true)
348
349 # ----- SDK for Windows ------
350 # These configure the build targets that are available for the SDK under Cygwin.
351 # The first section defines all the C/C++ tools that can be compiled under Cygwin,
352 # the second section defines all the Java ones (assuming javac is available.)
353
354 subdirs := \
355     prebuilt \
356     build/libs/host \
357     build/tools/zipalign \
...
382 # The following can only be built if "javac" is available.
383 # This check is used when building parts of the SDK under Cygwin.
384 ifneq (,$(shell which javac 2>/dev/null))
385 $(warning sdk-only: javac available.)
386 subdirs += \
387     build/tools/signapk \
388     dalvik/dx \
389     dalvik/libcore \
...
414 else    # !SDK_ONLY
415 ifeq ($(BUILD_TINY_ANDROID), true)
416
417 # TINY_ANDROID is a super-minimal build configuration, handy for board
418 # bringup and very low level debugging
419
420 subdirs := \
421     bionic \
422     system/core \
423     build/libs \
424     build/target \
...
433 else    # !BUILD_TINY_ANDROID
434
435 #
436 # Typical build; include any Android.mk files we can find.
437 #
438 subdirs := $(TOP)
439
440 FULL_BUILD := true
441
442 endif   # !BUILD_TINY_ANDROID
443
444 endif   # !SDK_ONLY
...
464 #
465 # Include all of the makefiles in the system
466 #
467
468 # Can't use first-makefiles-under here because
469 # --mindepth=2 makes the prunes not work.
470 subdir_makefiles := \
471     $(shell build/tools/findleaves.py --prune=out --prune=.repo --prune=.git $(subdirs) Android.mk)
472
473 include $(subdir_makefiles)
141 # Bring in standard build system definitions.
142 include $(BUILD_SYSTEM)/definitions.mk
...
347 ifeq ($(SDK_ONLY),true)
348
349 # ----- SDK for Windows ------
350 # These configure the build targets that are available for the SDK under Cygwin.
351 # The first section defines all the C/C++ tools that can be compiled under Cygwin,
352 # the second section defines all the Java ones (assu

补充：移动开发 , Android ,