构建基本的嵌入式Linux根文件系统

2019-07-12 22:28发布

在chinalinux论坛上看到了这篇文章,写得很好,转够来自己好好研究一下。下面是作者推荐的书,我都还没来得及看呢! 1、 《Linux系统移植》:一个经典的Linux移植文档,共有95页的PDF文档,内容十分详细,里面有根文件系统的创建,还多地方都有下载(有的网站称之为《Linux系统全线移植文档》等等),很值得参考。在这里感谢文档的作者们。 2、 《构建嵌入式Linux系统》必看!里面对文件系统的构建讲的挺细。 3、 《Filesystem Hierarchy Standard》Linux文件系统的标准规范。我只看到英文的。 其他再遇到不懂的就google,基本上都是Linux的相关知识,都是找得到的。
(1)创建根文件系统的基本目录结构。
我把这个过程做成了shell脚本(文件名为mkroot) ,很方便! #! /bin/sh
    echo "creatint rootfs dir......"
    mkdir rootfs
    cd rootfs

    echo "making dir : bin dev etc lib proc sbin sys usr"
    mkdir bin dev etc lib proc sbin sys usr #必备的8个目录
    mkdir usr/bin usr/lib usr/sbin lib/modules

# Don't use mknod ,unless you run this Script as root !
# mknod -m 600 dev/console c 5 1
# mknod -m 666 dev/null c 1 3       echo "making dir : mnt tmp var"
    mkdir mnt tmp var
    chmod 1777 tmp
    mkdir mnt/etc mnt/jffs2 mnt/yaffs mnt/data mnt/temp
    mkdir var/lib var/lock var/log var/run var/tmp 
    chmod 1777 var/tmp
      echo "making dir : home root boot"
    mkdir home root boot
    echo "done"  
    在你想要建立根文件系统的地方,运行: [tekkamanninja@Tekkaman-Ninja nfs]$ ./mkroot
creatint rootfs dir......
making dir : bin dev etc lib proc sbin sys usr
making dir : mnt tmp var
making dir : home root boot
done
[tekkamanninja@Tekkaman-Ninja nfs]$ cd rootfs/dev/
[tekkamanninja@Tekkaman-Ninja dev]$ su
口令:
[root@Tekkaman-Ninja dev]# mknod -m 600 console c 5 1;mknod -m 666 null c 1 3;exit
exit
[tekkamanninja@Tekkaman-Ninja dev]$

  2)配置、编译和安装Busybox-1.9.1 [tekkamanninja@Tekkaman-Ninja source]$ tar -xjvf busybox-1.9.1.tar.bz2
修改Makefile文件: [tekkamanninja@Tekkaman-Ninja busybox-1.9.1]$ pwd
/home/tekkamanninja/working/source/busybox-1.9.1
[tekkamanninja@Tekkaman-Ninja busybox-1.9.1]$ kwrite Makefile


......(第151-154行)
#SUBARCH := $(shell uname -m | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ /
#                 -e s/arm.*/arm/ -e s/sa110/arm/ /
#                 -e s/s390x/s390/ -e s/parisc64/parisc/ /
#                 -e s/ppc.*/powerpc/ -e s/mips.*/mips/ )
......(第174行附近)
#ARCH        ?= $(SUBARCH)
#CROSS_COMPILE    ?=
ARCH         = arm
CROSS_COMPILE = /home/tekkamanninja/working/gcc4.1.1/gcc-4.1.1-glibc-2.3.2/arm-9tdmi-linux-gnu/bin/arm-9tdmi-linux-gnu-

[tekkamanninja@Tekkaman-Ninja busybox-1.9.1]$ make menuconfig
[tekkamanninja@Tekkaman-Ninja busybox-1.9.1]$ make
......
  LINK busybox_unstripped
Trying libraries: crypt m
 Library crypt is needed
 Library m is needed
Final link with: crypt m
[tekkamanninja@Tekkaman-Ninja busybox-1.9.1]$ make install
我是动态编译所以查看一下需要的动态库   [tekkamanninja@Tekkaman-Ninja busybox-1.9.1]$ /home/tekkamanninja/working/gcc4.1.1/gcc-4.1.1-glibc-2.3.2/arm-9tdmi-linux-gnu/bin/arm-9tdmi-linux-gnu-readelf -d busybox

Dynamic section at offset 0xac014 contains 22 entries:
  Tag Type Name/Value
 0x00000001 (NEEDED) Shared library: [libcrypt.so.1]
 0x00000001 (NEEDED) Shared library: [libm.so.6]
 0x00000001 (NEEDED) Shared library: [libc.so.6]
 0x0000000c (INIT) 0xc0f0
 0x0000000d (FINI) 0x97608
 0x00000004 (HASH) 0x80e8
 0x00000005 (STRTAB) 0xa3c0
 0x00000006 (SYMTAB) 0x8b30
 0x0000000a (STRSZ) 3371 (bytes)
 0x0000000b (SYMENT) 16 (bytes)
 0x00000015 (DEBUG) 0x0
 0x00000003 (PLTGOT) 0xbc0ec
 0x00000002 (PLTRELSZ) 2976 (bytes)
 0x00000014 (PLTREL) REL
 0x00000017 (JMPREL) 0xb550
 0x00000011 (REL) 0xb4e0
 0x00000012 (RELSZ) 112 (bytes)
 0x00000013 (RELENT) 8 (bytes)
 0x6ffffffe (VERNEED) 0xb400
 0x6fffffff (VERNEEDNUM) 3
 0x6ffffff0 (VERSYM) 0xb0ec
 0x00000000 (NULL) 0x0

3)修改和创建必要的文件。   [tekkamanninja@Tekkaman-Ninja busybox-1.9.1]$ cp -a examples/bootfloppy/etc/* /home/tekkamanninja/working/nfs/rootfs/etc/ [tekkamanninja@Tekkaman-Ninja busybox-1.9.1]$ cd ../../nfs/rootfs/etc/ 1、增加为SHELL导入全局变量的文件/etc/profile [tekkamanninja@Tekkaman-Ninja etc]$ kwrite profile   # /etc/profile: system-wide .profile file for the Bourne shells
echo
echo "Processing /etc/profile... "
# no-op

# Set search library path
echo "Set search library path in /etc/profile"
export LD_LIBRARY_PATH=/lib:/usr/lib 

# Set user path
echo "Set user path in /etc/profile"
PATH=/bin:/sbin:/usr/bin:/usr/sbin
export PATH 

# Set PS1
#注意:ash 除了SHELL变量外,支持/u、/h、/W、/$、/!、/n、/w 、/nnn(ASCII字符对应的八进制数)
#以及/e[xx;xxm (彩 {MOD}特效)等等!
#而且前面还要多加一个 '/'
echo "Set PS1 in /etc/profile" export PS1="//e[05;32m[$USER@//w//a]//$//e[00;34m"   echo "Done" echo  
  2、增加初始化文件 [tekkamanninja@Tekkaman-Ninja etc]$ kwrite inittab ::sysinit:/etc/init.d/rcS
::respawn:-/bin/login
::restart:/sbin/init

::ctrlaltdel:/sbin/reboot
::shutdown:/bin/umount -a -r
::shutdown:/sbin/swapoff -a
  [tekkamanninja@Tekkaman-Ninja etc]$ kwrite fstab proc /proc proc defaults 0 0
none /tmp ramfs defaults 0 0
mdev /dev ramfs defaults 0 0
sysfs /sys sysfs defaults 0 0

      3、增加初始化脚本 [tekkamanninja@Tekkaman-Ninja etc]$ kwrite init.d/rcS #! /bin/sh
echo "----------mount all"
/bin/mount -a

echo "----------Starting mdev......"
/bin/echo /sbin/mdev > /proc/sys/kernel/hotplug
mdev -s

echo "*********************************************************"
echo " Tekkaman Ninja 2440 Rootfs(nfs) 2008.2 "
echo " Love Linux ! ! @@ Love Ke Ke ! ! "
echo "********************************************************"
    [tekkamanninja@Tekkaman-Ninja etc]$ rm *~ init.d/*~   5、为mdev创建配置文件 [tekkamanninja@Tekkaman-Ninja etc]$ vi mdev.conf 创建一个mdev.conf文件,内容可有可无。   4为使用用户登录功能移植TinyLogin 1、下载 http://tinylogin.busybox.net/ 下载tinylogin-snapshot.tar.bz2,并解压. [tekkamanninja@Tekkaman-Ninja source]$ tar -xjvf tinylogin-snapshot.tar.bz2   2、修改tinyLogin的Makefile [tekkamanninja@Tekkaman-Ninja source]$ cd tinylogin [tekkamanninja@Tekkaman-Ninja tinylogin]$ kwrite Makefile     指明tinyLogin使用自己来处理用户密码 USE_SYSTEM_PWD_GRP = false
......
CROSS =/home/tekkamanninja/working/gcc4.1.1/gcc-4.1.1-glibc-2.3.2/arm-9tdmi-linux-gnu/bin/arm-9tdmi-linux-gnu-
CC = $(CROSS)gcc
AR = $(CROSS)ar
STRIPTOOL = $(CROSS)strip
     3、 编译并安装  [tekkamanninja@Tekkaman-Ninja tinylogin]$ make PREFIX=/home/tekkamanninja/working/nfs/rootfs install
Aborting install -- You must be root, otherwise I can
't.
make tinylogin be setuid root, which will cause it to fail.  make: *** [install] 错误 1 [tekkamanninja@Tekkaman-Ninja tinylogin]$su 口令: [root@Tekkaman-Ninja tinylogin]# make PREFIX=/home/tekkamanninja/working/nfs/rootfs install [root@Tekkaman-Ninja tinylogin]# exit exit
   我是动态编译所以查看一下需要的动态库   [tekkamanninja@Tekkaman-Ninja tinylogin]$ /home/tekkamanninja/working/gcc4.1.1/gcc-4.1.1-glibc-2.3.2/arm-9tdmi-linux-gnu/bin/arm-9tdmi-linux-gnu-readelf -d tinylogin 

Dynamic section at offset 0x9670 contains 21 entries:
  Tag Type Name/Value
 0x00000001 (NEEDED) Shared library: [libcrypt.so.1]
 0x00000001 (NEEDED) Shared library: [libc.so.6]
 0x0000000c (INIT) 0x9c40
 0x0000000d (FINI) 0x10160
 0x00000004 (HASH) 0x8128
 0x00000005 (STRTAB) 0x9070
 0x00000006 (SYMTAB) 0x85e0
 0x0000000a (STRSZ) 1430 (bytes)
 0x0000000b (SYMENT) 16 (bytes)
 0x00000015 (DEBUG) 0x0
 0x00000003 (PLTGOT) 0x19740
 0x00000002 (PLTRELSZ) 1064 (bytes)
 0x00000014 (PLTREL) REL
 0x00000017 (JMPREL) 0x9818
 0x00000011 (REL) 0x97c8
 0x00000012 (RELSZ) 80 (bytes)  0x00000013 (RELENT) 8 (bytes)
 0x6ffffffe (VERNEED) 0x9758
 0x6fffffff (VERNEEDNUM) 2
 0x6ffffff0 (VERSYM) 0x9606
 0x00000000 (NULL) 0x0
  创建帐号及密码文件: [tekkamanninja@Tekkaman-Ninja tinylogin]$ cd ../../nfs/rootfs/etc/
[tekkamanninja@Tekkaman-Ninja etc]$
su
口令:
[root@Tekkaman-Ninja etc]# cp /etc/passwd . ;cp /etc/shadow . ;cp /etc/group .
[root@Tekkaman-Ninja etc]# kwrite passwd
root:x:0:0:root:/root:/bin/sh
[root@Tekkaman-Ninja etc]# kwrite group
root:x:0:root
[root@Tekkaman-Ninja etc]#
kwrite shadow
root:$1$N8K8eEQe$.XkJo3xcsjOE6vo1jW9Nk/:13923:0:99999:7:::

[root@Tekkaman-Ninja etc]#
rm *~
rm:是否删除 普通文件 “group~? y
rm:是否删除 普通文件 “passwd~? y
rm:是否删除 普通文件 “shadow~? y
[root@Tekkaman-Ninja etc]# exit
exit
[tekkamanninja@Tekkaman-Ninja etc]$
3个文件是从Host中拷贝来的