1- adroid 演進(jìn)過程

Android編譯演進(jìn)過程：

• Android7.0之前 使用GNU Make
• Android7.0 引入ninja枫吧、kati强岸、Android.bp和soong構(gòu)建系統(tǒng)
• Android8.0 默認(rèn)打開Android.bp

• Android9.0 強(qiáng)制使用Android.bp
  Make 構(gòu)建系統(tǒng)得到了廣泛的支持和使用胶坠，但在 Android 層面變得緩慢鸭叙、容易出錯(cuò)衣形、無法擴(kuò)展且難以測試嘉抒。Soong 構(gòu)建系統(tǒng)正好提供了 Android build 所需的靈活性权埠。

  
  

2- android build 流程

build/ 目錄下

• blueprint：用于處理Android.bp榨了，編譯生成*.ninja文件，用于做ninja的處理
• kati：用于處理Android.mk攘蔽，編譯生成*.ninja文件龙屉，用于做ninja的處理
• make：文件夾還是原始的make那一套流程，比如envsetup.sh

• soong：構(gòu)建系統(tǒng)满俗，核心編譯為soong_ui.bash

  
  

build 流程

3 編譯環(huán)境初始化

source build/envsetup.sh
輸入指令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 說明

通過soong執(zhí)行編譯構(gòu)建转捕，這里執(zhí)行make命令時(shí)，main.mk文件把一些環(huán)境變量和目標(biāo)都配置好后唆垃，會(huì)執(zhí)行envsetup.sh中的make()進(jìn)行編譯五芝。

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]  -------》 下面說明
# 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的編譯過程:

soong_ui.bash 調(diào)用流程：

可以看到include 了main.mk文件，從main.mk開始辕万，將通過include命令將其所有需要的.mk文件包含進(jìn)來枢步，最終在內(nèi)存中形成一個(gè)包括所有編譯腳本的集合，這個(gè)相當(dāng)于一個(gè)巨大Makefile文件渐尿。Makefile文件看上去很龐大醉途，其實(shí)主要由三種內(nèi)容構(gòu)成: 變量定義、函數(shù)定義和目標(biāo)依賴規(guī)則砖茸，此外mk文件之間的包含也很重要隘擎。

5.工具鏈的關(guān)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