原创 arm-linux学习之busybox文件系统（一）

 2008-12-29 23:00  6872 8 8 分类: MCU/ 嵌入式

    移植linux到arm平台，完成bootloader和kernel之后就要制作自己的文件系统。这个东西搞的大爷很惨，上网查了很多资料，最初是从cramfs文件系统开始，然后ramdisk的ext2文件系统，最后才是jffs2文件系统。开始是找不到系统，后来是can't access tty,joy control turn off,后来是不能运行自己的程序。不知道怎么淡出就没有作笔记的习惯，现在从新作同样的事情的时候却又不出现这样的问题了￥＃％＠＃……％￥……％
    （1）下载并且配置busybox，偶使用的版本是busybox-1.13.0.tar.gz，解压缩，

    [root@localhost busybox]# cd busybox-1.13.0
    [root@localhost busybox-1.13.0]# make menuconfig
    [root@localhost busybox-1.13.0]# make
    [root@localhost busybox-1.13.0]# make install PREFIX=_install
其中配置时:
Busybox Settings --->
     Build Options --->
        [ ] Build BusyBox as a static binary (no shared libs)      //采用静态编译的方式，不需要lib的支持，这种办法比较简单，但是不能运行自己的程序，所以选择下面的 Build shared libbusybox   方式，但是需要手动把运行程序以来的lib文件copy到/lib中。
        [ ]   Build BusyBox as a position independent executable
        [ ] Force NOMMU build

Build shared libbusybox
        [ ]   Produce a binary for each applet, linked against libbusybox
        [ ]   Produce additional busybox binary linked against libbusybox
        [ ] Build with Large File Support (for accessing files > 2 GB)
        (arm-9tdmi-linux-gnu-) Cross Compiler prefix //交叉编译

        其他各项的配置省略，把.config文件放在后面。使用命令执行make install PREFIX=_install执行安装，目标在_install目录之下。安装完成之后会得到以下几个目录和一个文件
[root@localhost _install]# ls
bin linuxrc sbin usr
[root@localhost _install]# ls -l
总计 28
drwxr-xr-x 2 root root 4096 11-30 04:22 bin
lrwxrwxrwx 1 root root   11 11-30 04:22 linuxrc -> bin/busybox
drwxr-xr-x 2 root root 4096 11-30 04:22 sbin
drwxr-xr-x 4 root root 4096 11-30 04:22 usr
    其中有个linuxrc文件，这就是默认情况下的脚本文件，一般需要自己编写这个文件。其实bosybox编译的结构就是一个二进制二文件busybosy，其他命令像ls，cd等等所有都是连接到busybox这个文件的。这一点比较＃＠＃￥＠＃％。
（二）制作跟文件系统
1、顶层文件系统
在/home/arm/建立一个root_dir的目录，然后在root_dir下面建立以下目录
[root@localhost root_dir]# ls
bin etc   lib     mnt   root sys usr
dev home lib64    proc sbin tmp var
再建立一个linuxrc的文件，将其属性改成可执行的脚本。
[root@localhost root_dir]# ls
bin etc   lib    linuxrc   mnt   root sys usr
dev home lib64    proc sbin tmp var
然后把刚才编译的busybox的的_install的bin   sbin usr这三个目录全部copy到/home/arm/root_dir
下。
查看一下
[root@localhost root_dir]# cd bin
[root@localhost bin]# ls
addgroup cp        egrep   login     mountpoint     rm         umount
adduser   cpio      fgrep   ls        mt             rmdir      uncompress
ash       date      grep    lsattr    mv             run-parts vi
busybox   delgroup gunzip makemime ping           sh         zcat
cat       deluser   gzip    mkdir     pipe_progress su
chattr    dmesg     ip      mknod     ps             tar
chmod     dumpkmap kill    mktemp    pwd            tinylogin
chown     echo      ln      mount     reformime      touch
[root@localhost bin]# ls -l
总计 1104
lrwxrwxrwx 1 root root      9 11-15 00:16 addgroup -> tinylogin
lrwxrwxrwx 1 root root      9 11-15 00:16 adduser -> tinylogin
lrwxrwxrwx 1 root root      7 11-30 04:24 ash -> busybox
-rwxr-xr-x 1 root root 431172 11-30 04:22 busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 cat -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 chattr -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 chmod -> busybox
lrwxrwxrwx 1 root root      7 11-18 03:18 chown -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 cp -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 cpio -> busybox
lrwxrwxrwx 1 root root      7 11-18 03:18 date -> busybox
lrwxrwxrwx 1 root root      9 11-15 00:16 delgroup -> tinylogin
lrwxrwxrwx 1 root root      9 11-15 00:16 deluser -> tinylogin
lrwxrwxrwx 1 root root      7 11-30 04:24 dmesg -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 dumpkmap -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 echo -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 egrep -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 fgrep -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 grep -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 gunzip -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 gzip -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 ip -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 kill -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 ln -> busybox
lrwxrwxrwx 1 root root      9 11-15 00:16 login -> tinylogin
lrwxrwxrwx 1 root root      7 11-30 04:24 ls -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 lsattr -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 makemime -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 mkdir -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 mknod -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 mktemp -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 mount -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 mountpoint -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 mt -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 mv -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 ping -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 pipe_progress -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 ps -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 pwd -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 reformime -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 rm -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 rmdir -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 run-parts -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 sh -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 su -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 tar -> busybox
-rwsr-xr-x 1 root root 473256 11-15 00:16 tinylogin
lrwxrwxrwx 1 root root      7 11-18 03:18 touch -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 umount -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 uncompress -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 vi -> busybox
lrwxrwxrwx 1 root root      7 11-30 04:24 zcat -> busybox
[root@localhost bin]#
2、设备节点
在dev目录下创建三个节点
[root@localhost dev]# ls -al
总计 28
crw-r--r-- 1 root root 5, 1 11-28 23:28 console
crw-r--r-- 1 root root 1, 3 11-14 23:57 null
crw-r--r-- 1 root root 1, 5 11-14 23:57 zero
当然这几个节点远远不够，需要的时候在给据major 和minor补充
3、inittab文件
    inittab是init程序的配置文件，busybox目录下有个exmples目录（/home/arm/busybox/busybox-1.13.0/examples）该目录下有个示例inittab
/home/arm/busybox/busybox-1.13.0/examples中inittab文件第38行到46行
# Note: BusyBox init works just fine without an inittab. If no inittab is
# found, it has the following default behavior:
#         ::sysinit:/etc/init.d/rcS
#         ::askfirst:/bin/sh
#         ::ctrlaltdel:/sbin/reboot
#         ::shutdown:/sbin/swapoff -a
#         ::shutdown:/bin/umount -a -r
#         ::restart:/sbin/init
#
# if it detects that /dev/console is _not_ a serial console, it will
# also run:
#         tty2::askfirst:/bin/sh
#         tty3::askfirst:/bin/sh
#         tty4::askfirst:/bin/sh

    如果出现can't access tty2,joy control turn off,等等，症结可能在这里。

    将/home/arm/busybox/busybox-1.13.0/examples/inittab 文件copy到/home/arm/root_dir/etc/目录下，并根据自己的要求修改就行了。(待续)

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