Android开发环境说明(一)

flagstaff@flagstaff-pc:~/aosp_r.lns/.repo/manifests$ git branch -a
* default
  remotes/m/android-11.0.0_r37 -> origin/android-11.0.0_r37
  remotes/m/android-11.0.0_r38 -> origin/android-11.0.0_r38

flagstaff@flagstaff-pc:~/aosp_r.lns/.repo/manifests$ git remote show origin
  ....
  Local branch configured for 'git pull':
    default merges with remote android-11.0.0_r38

flagstaff@flagstaff-pc:~/aosp_r.lns$ source build/envsetup.sh
flagstaff@flagstaff-pc:~/aosp_r.lns$ lunch 30
test/flagstaffTest/BoardConfig.mk:4: warning: "flagstaff BoardConfig.mk is included
test/flagstaffTest/device.mk:11: warning: "flagstaff device.mk is included."

============================================
PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=11
TARGET_PRODUCT=aosp_x86_64
TARGET_BUILD_VARIANT=eng
TARGET_BUILD_TYPE=release
TARGET_ARCH=x86_64
TARGET_ARCH_VARIANT=x86_64
TARGET_2ND_ARCH=x86
TARGET_2ND_ARCH_VARIANT=x86_64
HOST_ARCH=x86_64
HOST_2ND_ARCH=x86
HOST_OS=linux
HOST_OS_EXTRA=Linux-5.11.0-43-generic-x86_64-Ubuntu-20.04.2-LTS
HOST_CROSS_OS=windows
HOST_CROSS_ARCH=x86
HOST_CROSS_2ND_ARCH=x86_64
HOST_BUILD_TYPE=release
BUILD_ID=RQ3A.210605.005
OUT_DIR=out
PRODUCT_SOONG_NAMESPACES=device/generic/goldfish device/generic/goldfish-opengl hardware/google/camera hardware/google/camera/devices/EmulatedCamera device/generic/goldfish device/generic/goldfish-opengl
============================================

  不论出于什么目的基于AOSP进行功能开发都离不开编译、部署、运行这三步骤，对于这几个步骤Android则有其自己的一套的规则。每个模块则有专属的Android.mk、Android.bp来描述它的编译。在部署的时候会涉及是否打包到system/vendor/etc…，运行时Android则会检测将运行程序的sepolicy。为了将测试代码和AOSP代码隔离，测试代码的目录结构如下。

flagstaff@flagstaff-pc:~/aosp_r.lns/test/flagstaffTest$ tree
.
├── BoardConfig.mk
├── compatibility_matrix
├── device.mk
└── sepolicy

BoardConfig.mk
  同AOSP的BoardConfig.mk，用于放置板级配置。其被包含于device.mk

flagstaff@flagstaff-pc:~/aosp_r.lns/test/flagstaffTest$ cat device.mk
#For my Test
//file ~/aosp_r.lns/test/flagstaffTest/device.mk
...
include test/flagstaffTest/BoardConfig.mk
...

device.mk
  用于添加设备相关的配置信息，其被具体的产品所包含。测试时使用的lunch 30(x86_64)，包含信息如下

--- a/target/product/aosp_x86_64.mk
+++ b/target/product/aosp_x86_64.mk
@@ -63,6 +63,7 @@ $(call inherit-product, $(SRC_TARGET_DIR)/board/generic_x86_64/device.mk)
 ifeq (aosp_x86_64,$(TARGET_PRODUCT))
 $(call inherit-product, $(SRC_TARGET_DIR)/product/gsi_release.mk)
 endif
+$(call inherit-product, test/flagstaffTest/device.mk)

compatibility_matrix
  该目录用于包含兼容矩阵信息。其中文件的内容则用来描述framework请求vendor需要提供的组件信息，也被称为FCM，其组件图如下:

  上图则引用自android的vintf 章节。
  在编译时则需要使用位于Android编译系统的关键字添加，其内容位于device.mk中

file:device.mk
...
DEVICE_frameWORK_COMPATIBILITY_MATRIX_FILE += 
        test/flagstaffTest/compatibility_matrix/framework_compatibility_matrix.xml
...

sepolicy
  用于添加sepolicy信息，sepolicy在Android4.4就被强制开启了，所以新增加的可执行程序/文件如果没有正确配置sepolicy，那么会被系统拒绝运行及访问。

flagstaff@flagstaff-pc:~/aosp_r.lns/test/flagstaffTest$ cat BoardConfig.mk
BOARD_VENDOR_SEPOLICY_DIRS += 
    test/flagstaffTest/sepolicy
...

  如果想详细了解作用及使用规则可以按官网的学习路线进行。
google sepolicy detail