用busybox创建基于Linux2.6.24内核的nfs根文件系统 (2008-07-13 20:39)

分类： Linux内核

Jacky Xu @ 2008.7.13

一、主机环境
  Linux version 2.4.20-8, RedHat9, VMWare5.5.3;
  gcc version 3.4.4, Thread model: posix;
  GNU Make 3.81;
  arm-linux-gcc 4.2.1 （此创建过程见另贴用crosstool脚本编译针对Linux2.6内核的交叉编译工具链）
  所需源文件：
  busybox-1.11.1.tar.bz2;

二、用Busybox创建nfs文件系统

1、解压busybox-1.11.1.tar.bz2，路径为
[root@Sure busybox-1.11.1]# pwd

/home/jacky/busybox-1.11.1

修改Makefilez中的ARCH和CROSS_COMPILE与本机的路径一致：

CROSS_COMPILE ?= /opt/crosstool/bin/arm-s3c2410-linux-gnu-
...
ARCH ?= arm

2、编译busybox。先make menuconfig，修改以下：

Busybox Settings --->
    Build Options --->
        [*] Build BusyBox as a static binary (no shared libs)
        //直接编译成静态库，省事点
        (/opt/crosstool/bin/arm-s3c2410-linux-gnu-) Cross Compiler prefix
        //这里和Makefile里保持一致，应该写一处就行了
    Installation Options --->
        [*] Don't use /usr
        //不用本机的目录
Shells --->
    Choose your default shell (ash) --->
    //这里选择shell为ash，应该是默认选中的
        --- ash
        //把ash这档的选项全部选上

保存退出，直接make，make install。

3、用shell脚本创建根文件系统的目录结构，并在想要建立根文件系统的地方运行此脚本。我是用root用户登陆的，直接创建了设备节点。
[root@Sure root-s3c2410]# vim makedir.sh

#!/bin/sh
  echo "makeing rootdir"
  mkdir rootfs
  cd rootfs

  echo "makeing dir: bin dev etc lib proc sbin sys usr"
  mkdir bin dev etc lib proc sbin sys usr #8 dirs
  mkdir usr/bin usr/lib usr/sbin lib/modules

#Don't use mknod, unless you run this Script as
  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/jiffs2 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"

执行这个sh：
[root@Sure root-s3c2410]# sh makedir.sh
创建出一个主文件夹rootfs，里面有一批文件：
[root@Sure rootfs]# ls
bin  boot  dev  etc  home  lib  mnt  proc  root  sbin  sys  tmp  usr  var

4、把busybox源码目录下的etc的内容拷贝到这里的etc下
[root@Sure rootfs]# cd etc/
[root@Sure etc]# cp -a /home/jacky/busybox-1.11.1/examples/bootfloppy/etc/* ./

5、修改拷贝过来的profile文件
[root@Sure etc]# vim profile

# /etc/profile: system-wide .profile file for the Bourne shells

echo "Processing /etc/profile"
# no-op

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

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

# Set PS1
echo " Set PS1"
HOSTNAME=`/bin/hostname`
# 此处让shell提示符显示host名称的。是`，不是’，要注意
# 会在进入根系统后显示Jacky

export PS1="\\e[32m[$USER@$HOSTNAME \\w\\a]\\$\\e[00;37m "
# 此处\\e[32m是让后面的“[$USER@$HOSTNAME \\w\\a]”显示为绿色
# \\e[00是关闭效果
# \\e[05是闪烁
# 37m是让后面的显示为白色
# 多个命令可以；号隔开


echo "All done!"
echo

6、修改初始化文件inittab和fstab
[root@Sure etc]# vim inittab

::sysinit:/etc/init.d/rcS
::respawn:-/bin/sh
::restart:/sbin/init

tty2::askfirst:-/bin/sh
::ctrlaltdel:/bin/umount -a -r
::shutdown:/bin/umount -a -r
::shutdown:/sbin/swapoff –a

[root@Sure etc]# vim 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

7、修改初始化的脚本文件init.d/rcS
[root@Sure etc]# vim init.d/rcS

#! /bin/sh
echo "Processing etc/init.d/rc.S"

#hostname ${HOSTNAME}

echo " Mount all"
/bin/mount -a

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

echo "****************************************************"
echo " RootFS by NFS, s3c2410"
echo " Created by Jacky Xu @ 2008.7.13"
echo " Enjoy it!!!"
echo "****************************************************"
echo

8、创建一个空的mdev.conf文件，在挂载根文件系统时会用到的
[root@Sure etc]# touch mdev.conf

9、从本机拷贝passwd、shadow、group文件。
[root@Sure etc]# cp /etc/passwd .
[root@Sure etc]# cp /etc/shadow .
[root@Sure etc]# cp /etc/group .
修改passwd文件，把第一行和最后一行的bash修改成ash。

10、把busybox默认安装目录中的文件全部复制到这里的rootfs中。会发现多了linuxrc -> bin/busybox文件，这是挂载文件系统需要执行的。
[root@Sure etc]# cd ..
[root@Sure rootfs]# cp -Rfv /home/jacky/busybox-1.11.1/_install/ ./

OK，以上用busybox创建了一个基本的文件系统。
PS:
    如果编译busybox时选择动态库方式编译，则需要查看生成的busybox使用哪些动态库，然后把它们拷贝到rootfs/lib目录下。
[root@Sure lib]# arm-s3c2410-linux-gnu-readelf -d ../bin/busybox

Dynamic section at offset 0xc1014 contains 21 entries:
  Tag Type Name/Value
 0x00000001 (NEEDED) Shared library: [libm.so.6]
 0x00000001 (NEEDED) Shared library: [libc.so.6]
 0x0000000c (INIT) 0xc2ec
 0x0000000d (FINI) 0xa96b8
 0x00000004 (HASH) 0x80e8
 0x00000005 (STRTAB) 0xa4c4
 0x00000006 (SYMTAB) 0x8b64
 0x0000000a (STRSZ) 3505 (bytes)
 0x0000000b (SYMENT) 16 (bytes)
 0x00000015 (DEBUG) 0x0
 0x00000003 (PLTGOT) 0xd10e4
 0x00000002 (PLTRELSZ) 3112 (bytes)
 0x00000014 (PLTREL) REL
 0x00000017 (JMPREL) 0xb6c4
 0x00000011 (REL) 0xb674
 0x00000012 (RELSZ) 80 (bytes)
 0x00000013 (RELENT) 8 (bytes)
 0x6ffffffe (VERNEED) 0xb5a4
 0x6fffffff (VERNEEDNUM) 2
 0x6ffffff0 (VERSYM) 0xb276
 0x00000000 (NULL) 0x0

可以看出，使用了libm.so.6和libc.so.6两个库。发现只拷贝这两个库还不够，还需要ld-linux.so.2和libgcc_s.so.1，也就是我编译出来的这个busybox需要4个动态库文件。
# cp /opt/crosstool/arm-s3c2410-linux-gnu/sys-root/lib/libm.so.6 .
# cp /opt/crosstool/arm-s3c2410-linux-gnu/sys-root/lib/libc.so.6 .
# cp /opt/crosstool/arm-s3c2410-linux-gnu/sys-root/lib/ld-linux.so.2 .
# cp /opt/crosstool/arm-s3c2410-linux-gnu/lib/libgcc_s.so.1 .
这样，使用动态库可以节省一半左右的空间，不过效率有所降低。

三、测试
1、在本机修改/etc/export文件，重启NFS服务：
[root@Sure rootfs]# vim /etc/exports
/home/jacky/root-s3c2410/rootfs 192.168.1.*(rw,sync,no_root_squash)
[root@Sure rootfs]# service nfs restart

2、在Bootloader中传递以下参数给Kernel：
root=/dev/nfs rw nfsroot=192.168.1.249:/home/jacky/root-s3c2410/rootfs ip=192.168.1.199:192.168.1.249:192.168.1.1:255.255.255.0:Jacky:eth0:off console=ttySAC0,115200 init=/linuxrc noinitrd

3、启动目标板，串口输出显示根文件系统已经加载成功：

Boot Parameters: root=/dev/nfs rw nfsroot=192.168.1.249:/home/jacky/root-s3c2410/rootfs ip=192.168.1.199:192.168.1.249:192.168.1.1:255.255.255.0:Jacky:eth0:off console=ttySAC0,115200 init=/linuxrc noinitrd
Now, booting Linux...
Uncompressing Linux........................................................................................................... done, booting the kernel.
Linux version 2.6.24.7 (root@Sure) (gcc version 4.2.1) #5 Sat Jul 12 17:26:16 CST 2008
CPU: ARM920T [41129200] revision 0 (ARMv4T), cr=c0007177
Machine: SMDK2410
ATAG_INITRD is deprecated; please update your bootloader.
Memory policy: ECC disabled, Data cache writeback
CPU S3C2410A (id 0x32410002)
S3C2410: core 200.000 MHz, memory 100.000 MHz, peripheral 50.000 MHz
S3C24XX Clocks, (c) 2004 Simtec Electronics
CLOCK: Slow mode (1.500 MHz), fast, MPLL on, UPLL on
CPU0: D VIVT write-back cache
CPU0: I cache: 16384 bytes, associativity 64, 32 byte lines, 8 sets
CPU0: D cache: 16384 bytes, associativity 64, 32 byte lines, 8 sets
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 16256
Kernel command line: root=/dev/nfs rw nfsroot=192.168.1.249:/home/jacky/root-s3c2410/rootfs ip=192.168.1.199:192.168.1.249:192.168.1.1:255.255.255.0:Jacky:eth0:off console=ttySAC0,115200 init=/linuxrc noinitrd
irq: clearing subpending status 00000003
PID hash table entries: 256 (order: 8, 1024 bytes)
timer tcon=00000000, tcnt a2c1, tcfg 00000200,00000000, usec 00001eb8
Console: colour dummy device 80x30
console [ttySAC0] enabled
Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
Memory: 64MB = 64MB total
Memory: 61440KB available (3048K code, 314K data, 128K init)
Mount-cache hash table entries: 512
CPU: Testing write buffer coherency: ok
net_namespace: 64 bytes
NET: Registered protocol family 16
S3C2410 Power Management, (c) 2004 Simtec Electronics
S3C2410: Initialising architecture
S3C24XX DMA Driver, (c) 2003-2004,2006 Simtec Electronics
DMA channel 0 at c4800000, irq 33
DMA channel 1 at c4800040, irq 34
DMA channel 2 at c4800080, irq 35
DMA channel 3 at c48000c0, irq 36
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
Bluetooth: Core ver 2.11
NET: Registered protocol family 31
Bluetooth: HCI device and connection manager initialized
Bluetooth: HCI socket layer initialized
NET: Registered protocol family 2
IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
TCP established hash table entries: 2048 (order: 2, 16384 bytes)
TCP bind hash table entries: 2048 (order: 1, 8192 bytes)
TCP: Hash tables configured (established 2048 bind 2048)
TCP reno registered
NetWinder Floating Point Emulator V0.97 (double precision)
JFFS2 version 2.2. (NAND) © 2001-2006 Red Hat, Inc.
JFS: nTxBlock = 480, nTxLock = 3840
io scheduler noop registered
io scheduler anticipatory registered (default)
io scheduler deadline registered
io scheduler cfq registered
s3c2410-lcd s3c2410-lcd: no platform data for lcd, cannot attach
s3c2410-lcd: probe of s3c2410-lcd failed with error -22
lp: driver loaded but no devices found
ppdev: user-space parallel port driver
Serial: 8250/16550 driver $Revision: 1.90 $ 4 ports, IRQ sharing enabled
s3c2410-uart.0: s3c2410_serial0 at MMIO 0x50000000 (irq = 70) is a S3C2410
s3c2410-uart.1: s3c2410_serial1 at MMIO 0x50004000 (irq = 73) is a S3C2410
s3c2410-uart.2: s3c2410_serial2 at MMIO 0x50008000 (irq = 76) is a S3C2410
RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize
loop: module loaded
Cirrus Logic CS8900A driver for Linux (Modified for SMDK2410)
eth0: CS8900A rev E at 0xe0000300 irq=53, addr: 00: 0:3E:26:0A: 0
Uniform Multi-Platform E-IDE driver Revision: 7.00alpha2
ide: Assuming 50MHz system bus speed for PIO modes; override with idebus=xx
S3C24XX NAND Driver, (c) 2004 Simtec Electronics
s3c2410-nand s3c2410-nand: Tacls=3, 30ns Twrph0=7 70ns, Twrph1=3 30ns
NAND device: Manufacturer ID: 0xec, Chip ID: 0x76 (Samsung NAND 64MiB 3,3V 8-bit)
Scanning device for bad blocks
Creating 5 MTD partitions on "NAND 64MiB 3,3V 8-bit":
0x00000000-0x00100000 : "Bootloader"
0x00100000-0x00400000 : "Kernel"
0x00400000-0x03400000 : "Root"
0x03400000-0x03fe0000 : "ExtRoot"
0x03fe0000-0x04000000 : "Param"
usbmon: debugfs is not available
s3c2410-ohci s3c2410-ohci: S3C24XX OHCI
s3c2410-ohci s3c2410-ohci: new USB bus registered, assigned bus number 1
s3c2410-ohci s3c2410-ohci: irq 42, io mem 0x49000000
usb usb1: configuration #1 chosen from 1 choice
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 2 ports detected
mice: PS/2 mouse device common for all mice
S3C24XX RTC, (c) 2004,2006 Simtec Electronics
s3c2410-i2c s3c2410-i2c: slave address 0x10
s3c2410-i2c s3c2410-i2c: bus frequency set to 390 KHz
s3c2410-i2c s3c2410-i2c: i2c-0: S3C I2C adapter
S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics
s3c2410-wdt s3c2410-wdt: watchdog inactive, reset disabled, irq enabled
TCP cubic registered
NET: Registered protocol family 1
NET: Registered protocol family 17
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
drivers/rtc/hctosys.c: unable to open rtc device (rtc0)
IP-Config: Complete:
      device=eth0, addr=192.168.1.199, mask=255.255.255.0, gw=192.168.1.1,
     host=Jacky, domain=, nis-domain=(none),
     bootserver=192.168.1.249, rootserver=192.168.1.249, rootpath=
Looking up port of RPC 100003/2 on 192.168.1.249
Looking up port of RPC 100005/1 on 192.168.1.249
VFS: Mounted root (nfs filesystem).
Freeing init memory: 128K
init started: BusyBox v1.11.1 (2008-07-13 14:46:21 CST)
starting pid 789, tty '': '/etc/init.d/rcS'
Processing etc/init.d/rc.S
  Mount all
  Start mdev....
****************************************************
              RootFS by NFS, s3c2410
         Created by Jacky Xu @ 2008.7.13
                   Enjoy
****************************************************

starting pid 793, tty '': '-/bin/sh'
Processing /etc/profile
  Set search library path
  Set user path
  Set PS1
All

[root@Jacky /]# ls
bin dev home linuxrc proc sbin tmp var
boot etc lib mnt root sys usr
[root@Jacky /]#


已经直接进入了nfs文件系统！
-----------------------------------
  Jacky_Xu @ 2008.7.13
  MSN: [e-mail]
  E-mail: [e-mail]
-----------------------------------