i.mx6 Android5.1.1 build解析

参考资料：理解 Android Build 系统

把总结放前面：

1. 常用编译命令

make clean	执行清理，等同于：rm -rf out/。
make sdk	编译出 Android 的 SDK。
make clean-sdk	清理 SDK 的编译产物。
make update-api	更新 API。在 framework API 改动之后，需要首先执行该命令来更新 API，公开的 API 记录在 frameworks/base/api 目录下。
make dist	执行 Build，并将 MAKECMDGOALS 变量定义的输出文件拷贝到 /out/dist 目录。
make all	编译所有内容，不管当前产品的定义中是否会包含。
make help	帮助信息，显示主要的 make 目标。
make snod	从已经编译出的包快速重建系统镜像。
make libandroid_runtime	编译所有 JNI framework 内容。
make framework	编译所有 Java framework 内容。
make services	编译系统服务和相关内容。
make <local_target>	编译一个指定的模块，local_target 为模块的名称。
make clean-<local_target>	清理一个指定模块的编译结果。
make dump-products	显示所有产品的编译配置信息，例如：产品名，产品支持的地区语言，产品中会包含的模块等信息。
make PRODUCT-xxx-yyy	编译某个指定的产品。
make bootimage	生成 boot.img
make recoveryimage	生成 recovery.img
make userdataimage	生成 userdata.img
make cacheimage	生成 cache.img

2.常用命令：

名称	说明
croot	切换到源码树的根目录
m	在源码树的根目录执行 make
mm	Build 当前目录下的模块
mmm	Build 指定目录下的模块
cgrep	在所有 C/C++ 文件上执行 grep
jgrep	在所有 Java 文件上执行 grep
resgrep	在所有 res/*.xml 文件上执行 grep
godir	转到包含某个文件的目录路径
printconfig	显示当前 Build 的配置信息
add_lunch_combo	在 lunch 函数的菜单中添加一个条目

我们正常步骤为：

1). source build/envsetup.sh

2). lunch

3). make -jx

build/envsetup.sh

打开build/envsetup.sh，发现里面全都是函数，折叠全部函数，一直拖到最后，发现代码

if [ "x$SHELL" != "x/bin/bash" ]; then
    case `ps -o command -p $$` in
        *bash*)
            ;;
        *)
            echo "WARNING: Only bash is supported, use of other shell would lead to erroneous results"
            ;;
    esac
fi

# Execute the contents of any vendorsetup.sh files we can find.
#包含各种vendorsetup.s脚本文件进来，然后去执行 

for f in `test -d device && find -L device -maxdepth  -name 'vendorsetup.sh' > /dev/null` \

         `test -d vendor && find -L vendor -maxdepth  -name 'vendorsetup.sh' > /dev/null`
do
    echo "including $f"
    . $f
done
unset f

addcompletions

查看发现没错，查看lunch

function lunch()
{
    local answer
　　#如果有第一个参数
    if [ "$1" ] ; then
        answer=$
    else  #如果没有参数，就进入print_lunch_menu函数
        print_lunch_menu
        echo -n "Which would you like? [aosp_arm-eng] "
        read answer
    fi

    local selection=

    if [ -z "$answer" ]
    then
        selection=aosp_arm-eng
    elif (echo -n $answer | grep -q -e "^[0-9][0-9]*$")
    then
        if [ $answer -le ${#LUNCH_MENU_CHOICES[@]} ]
        then
            selection=${LUNCH_MENU_CHOICES[$(($answer-))]}
        fi
    elif (echo -n $answer | grep -q -e "^[^\-][^\-]*-[^\-][^\-]*$")
    then
        selection=$answer
    fi

    if [ -z "$selection" ]
    then
        echo
        echo "Invalid lunch combo: $answer"
        return
    fi

    export TARGET_BUILD_APPS=

    local product=$(echo -n $selection | sed -e "s/-.*$//")
    check_product $product
    if [ $? -ne  ]
    then
        echo
        echo "** Don't have a product spec for: '$product'"
        echo "** Do you have the right repo manifest?"
        product=
    fi

    local variant=$(echo -n $selection | sed -e "s/^[^\-]*-//")
    check_variant $variant
    if [ $? -ne  ]
    then
        echo
        echo "** Invalid variant: '$variant'"
        echo "** Must be one of ${VARIANT_CHOICES[@]}"
        variant=
    fi

    if [ -z "$product" -o -z "$variant" ]
    then
        echo
        return
    fi
　　#到处环境变量
    export TARGET_PRODUCT=$product
    export TARGET_BUILD_VARIANT=$variant
    export TARGET_BUILD_TYPE=release

    echo

    set_stuff_for_environment
    printconfig
}

function hmm() {
cat <<EOF
Invoke ". build/envsetup.sh" from your shell to add the following functions to your environment:
- lunch:   lunch <product_name>-<build_variant>
- tapas:   tapas [<App1> <App2> ...] [arm|x86|mips|armv5|arm64|x86_64|mips64] [eng|userdebug|user]
- croot:   Changes directory to the top of the tree.
- 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.
- 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.
- sgrep:   Greps on all local source files.
- godir:   Go to the directory containing a file.

Look at the source to view more functions. The complete list is:
EOF
    T=$(gettop)
    local A
    A=""
    for i in `cat $T/build/envsetup.sh | sed -n "/^[ \t]*function /s/function \([a-z_]*\).*/\/p" | sort | uniq`; do
      A="$A $i"
    done
    echo $A
}