Android make 基础

1- adroid 演进过程

Android编译演进过程：

• Android7.0之前 使用GNU Make
• Android7.0 引入ninja、kati、Android.bp和soong构建系统
• Android8.0 默认打开Android.bp

• Android9.0 强制使用Android.bp
  Make 构建系统得到了广泛的支持和使用，但在 Android 层面变得缓慢、容易出错、无法扩展且难以测试。Soong 构建系统正好提供了 Android build 所需的灵活性。

  
  

2- android build 流程

build/ 目录下

• blueprint：用于处理Android.bp，编译生成*.ninja文件，用于做ninja的处理
• kati：用于处理Android.mk，编译生成*.ninja文件，用于做ninja的处理
• make：文件夹还是原始的make那一套流程，比如envsetup.sh

• soong：构建系统，核心编译为soong_ui.bash

  
  

build 流程

3 编译环境初始化

source build/envsetup.sh
输入指令hmm 就可以查看信息

Run "m help" for help with the build system itself.

Invoke ". build/envsetup.sh" from your shell to add the following functions to your environment:
- lunch:      lunch <product_name>-<build_variant>
              Selects <product_name> as the product to build, and <build_variant> as the variant to
              build, and stores those selections in the environment to be read by subsequent
              invocations of 'm' etc.
- tapas:      tapas [<App1> <App2> ...] [arm|x86|mips|arm64|x86_64|mips64] [eng|userdebug|user]
- croot:      Changes directory to the top of the tree, or a subdirectory thereof.
- m:          Makes from the top of the tree.
- mm:         Builds all of the modules in the current directory, but not their dependencies.
- mmm:        Builds all of the modules in the supplied directories, but not their dependencies.
              To limit the modules being built use the syntax: mmm dir/:target1,target2.
- mma:        Builds all of the modules in the current directory, and their dependencies.
- mmma:       Builds all of the modules in the supplied directories, and their dependencies.
- provision:  Flash device with all required partitions. Options will be passed on to fastboot.
- cgrep:      Greps on all local C/C++ files.
- ggrep:      Greps on all local Gradle files.
- jgrep:      Greps on all local Java files.
- resgrep:    Greps on all local res/*.xml files.
- mangrep:    Greps on all local AndroidManifest.xml files.
- mgrep:      Greps on all local Makefiles files.
- sepgrep:    Greps on all local sepolicy files.
- sgrep:      Greps on all local source files.
- godir:      Go to the directory containing a file.
- allmod:     List all modules.
- gomod:      Go to the directory containing a module.
- pathmod:    Get the directory containing a module.
- refreshmod: Refresh list of modules for allmod/gomod.

Environment options:
- SANITIZE_HOST: Set to 'true' to use ASAN for all host modules. Note that
                 ASAN_OPTIONS=detect_leaks=0 will be set by default until the
                 build is leak-check clean.
- ANDROID_QUIET_BUILD: set to 'true' to display only the essential messages.

lunch 2

PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=10
TARGET_PRODUCT=aosp_arm64
TARGET_BUILD_VARIANT=eng
TARGET_BUILD_TYPE=release
TARGET_ARCH=arm64
TARGET_ARCH_VARIANT=armv8-a
TARGET_CPU_VARIANT=generic
TARGET_2ND_ARCH=arm
TARGET_2ND_ARCH_VARIANT=armv8-a
TARGET_2ND_CPU_VARIANT=generic
HOST_ARCH=x86_64
HOST_2ND_ARCH=x86
HOST_OS=linux
HOST_OS_EXTRA=Linux-4.15.0-137-generic-x86_64-Ubuntu-16.04.7-LTS
HOST_CROSS_OS=windows
HOST_CROSS_ARCH=x86
HOST_CROSS_2ND_ARCH=x86_64
HOST_BUILD_TYPE=release
BUILD_ID=QD4A.200805.003
OUT_DIR=out

4-make 说明

通过soong执行编译构建，这里执行make命令时，main.mk文件把一些环境变量和目标都配置好后，会执行envsetup.sh中的make()进行编译。

function make()
{
    _wrap_build $(get_make_command "$@") "$@"
}
function get_make_command()
{
    # If we're in the top of an Android tree, use soong_ui.bash instead of make
    if [ -f build/soong/soong_ui.bash ]; then
        # Always use the real make if -C is passed in
        for arg in "$@"; do
            if [[ $arg == -C* ]]; then
                echo command make
                return
            fi
        done
        echo build/soong/soong_ui.bash --make-mode
    else
        echo command make
    fi
}

build/soong/soong_ui.bash --make-mode
------->

[build/soong/soong_ui.bash]  -------》 下面说明
# Save the current PWD for use in soong_ui
export ORIGINAL_PWD=${PWD}
export TOP=$(gettop)
source ${TOP}/build/soong/scripts/microfactory.bash
soong_build_go soong_ui android/soong/cmd/soong_ui  -->生成soog_ui
cd ${TOP}  --->return root
exec "$(getoutdir)/soong_ui" "$@"------>exec  out/soong_ui  --make-mode build
“echo build/soong/soong_ui.bash --make-mode ”

soong的编译过程:

soong_ui.bash 调用流程：

可以看到include 了main.mk文件，从main.mk开始，将通过include命令将其所有需要的.mk文件包含进来，最终在内存中形成一个包括所有编译脚本的集合，这个相当于一个巨大Makefile文件。Makefile文件看上去很庞大，其实主要由三种内容构成: 变量定义、函数定义和目标依赖规则，此外mk文件之间的包含也很重要。

文件	作用
build/make/core/main.mk	Build的主控文件，主要作用是包含其他mk，以及定义几个最重要的编译目标，同时检查编译工具的版本，例如如gcc、clang、java等
build/make/core/config.mk	Build的配置文件，主要是区分各个产品的配置，并将这些编译器参数引入产品配置 BoardConfig.mk,同时也配置了一些编译器的路径等
build/make/core/definitions.mk	最重要的 Make 文件之一，在其中定义了大量的函数。这些函数都是 Build 系统的其他文件将用到的。例如：my-dir，all-subdir-makefiles，find-subdir-files，sign-package 等，关于这些函数的说明请参见每个函数的代码注释。
build/make/core/dex_preopt.mk	定义了dex优化相关的路径和参数

5.工具链的关系

Android.bp --> Blueprint --> Soong --> Ninja 
Makefile or Android.mk --> kati --> Ninja 

(Android.mk --> Soong --> Blueprint --> Android.bp)

REF
https://blog.csdn.net/yiranfeng/article/details/109082489