busybox分析--1.总

一.
1. 用git管理代码
1.1 用git管理代码

cong@msi:/work/busybox$ git init
Initialized empty Git repository in /work/busybox/.git/
cong@msi:/work/busybox$ git add ./
cong@msi:/work/busybox$ git commit -m 'busybox project init'
[master (root-commit) f641676] busybox project init

1.2 将临时文件重定向到_install目录
中间编译的.o文件及编译配置文件(.config.in)会频繁改动,为了避免这些临时文件的干扰，
需要将所有的临时文件定向到_install目录中, 加上O=./_install选项就可以了。

cong@msi:/work/busybox$ mkdir _install
cong@msi:/work/busybox$ make O=./_install/ menuconfig

cong@msi:/work/busybox$ make O=./_install/ -j16

1.3 过滤
生一利必有一弊,这儿需要将新建的_install目录过滤掉,同时将.gitignore添加到工程

cong@msi:/work/busybox$ git status
On branch master
Untracked files:
  (use "git add ..." to include in what will be committed)

    _install/


cong@msi:/work/busybox$ vi .gitignore     //新建一个.gitignore文件
cong@msi:/work/busybox$ cat .gitignore    //这个.gitignore文件的内容就是要过滤的文件或目录
readme
_install/
docs/

cong@msi:/work/busybox$ git status       //再将.gitignore添加到工程就可以了
On branch master
Untracked files:
  (use "git add ..." to include in what will be committed)

    .gitignore

2.编译
2.1 参写INSTALL

The BusyBox build process is similar to the Linux kernel build:

  make menuconfig       # This creates a file called ".config"
  make                  # This creates the "busybox" executable
  make install          # or make CONFIG_PREFIX=/path/from/root install

2.2 编译脚本

cong@msi:/work/busybox$ cat readme
#!/bin/sh
my_build()
{
    if [ ! -d ./_install ]; then
        mkdir ./_install
        make O=./_install/ menuconfig
    fi
    make O=./_install/ -j16
}

case "$1" in
    build)
        my_build
        ;;
    *)
        my_build
        ;;
esac

这样编译时直接运行 . readme就可以了,多快好省
3. 添加打印

在include/libbb.h的最后L2085
#define dbmsg(fmt, args ...) printf("%s:%s[%d]: "fmt"\n", __FILE__,__FUNCTION__, __LINE__,##args)

注:如果make menuconfig通不过,需要库

cong@msi:/work/busybox$ sudo apt-get install libncurses5-dev

三. ndk编译buysbox
1. 下载busybox-1.20.2在源码的configs目录下有android_ndk_defconfig

cong@msi:/work/busybox-1.20.2$ ls configs/
android2_defconfig  android_defconfig  android_ndk_defconfig
cygwin_defconfig  freebsd_defconfig  TEST_nommu_defconfig  TEST_noprintf_defconfig  TEST_rh9_defconfig

2. 编译过程

a. 修改Makefile指定ARCH与CROSS_COMPILE
 vi Makefile
 164 CROSS_COMPILE ?=/work/bak/android/android-ndk-r10e/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/arm-linux-androideabi-

 190 #ARCH ?= $(SUBARCH)
 191 ARCH ?=arm

b.修改config文件指定sys_root
 vi ./configs/android_ndk_defconfig
   68 CONFIG_SYSROOT="/work/bak/android/android-ndk-r10e/platforms/android-9/arch-arm"

cong@msi:/work/busybox-1.20.2$ make android_ndk_defconfig
cong@msi:/work/busybox-1.20.2$ make

3. 最后链接不过的解决方法

Then it dies with "ld: internal error in do_print_to_mapfile, at
/s/ndk-toolchain/src/build/../binutils/binutils-2.25/gold/output.h:395" due to
Google changing it to use gold linker by default.
Fixed by appending -fuse-ld=bfd to CFLAGS

Updated android_ndk_defconfig and patch for udhcpc attached.

vi Makefile 
     319 CFLAGS      := $(CFLAGS) -fuse-ld=bfd

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