构建嵌入式Linux根文件系统

移植好了UBOOT和内核之后，便是构建linux根文件系统了。以http://blog.chinaunix.net/u1/34474/showart_485837.html文章为基础进行修改。

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：

[HongGe@Hzh1024n]$ ./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
[HongGe@Hzh1024n]$ cd rootfs/dev/
[HongGe@Hzh1024n dev]$ su
口令：
[root@Hzh1024n dev]# mknod -m 600 console c 5 1;mknod -m 666 null c 1 3;exit
exit
[HongGe@Hzh1024n dev]$

2）配置、编译和安装Busybox-1.9.0

[HongGe@Hzh1024n source]$ tar -xjvf busybox-1.9.0.tar.bz2


修改Makefile文件：

[HongGe@Hzh1024n busybox-1.9.0]$ pwd
/home/work/hzh1024n/source/busybox-1.9.0
[HongGe@Hzh1024n busybox-1.9.0]$ kwrite Makefile

......(第174行附近)
#ARCH        ?= $(SUBARCH)
#CROSS_COMPILE    ?=
ARCH         = arm
CROSS_COMPILE = /usr/local/arm/3.3.2/bin/arm-linux-
[HongGe@Hzh1024n busybox-1.9.0]$ make menuconfig

 

在原有的基础上修改如下：

 

Busybox Settings --->
      Installation Options --->
           [*] Don't use /usr

           (/home/work/hzh1024n/rootfs) BusyBox installation prefix

        Busybox Library Tuning  --->

           [*] Support for /etc/networks

           [*]   Additional editing keys     

           [*]   vi-style line editing commands   

           (15)  History size  

           [*]   History saving  

           [*]   Tab completion 

           [*]     Username completion  

           [*]   Fancy shell prompts

 

Linux Module Utilities  ---> 

      [N] Support version 2.2.x to 2.4.x Linux kernels

Shells  --->

      ---   Ash Shell Options 下的选项全选

[HongGe@Hzh1024n busybox-1.9.0]$ make
......
  LINK busybox_unstripped
Trying libraries: crypt m
 Library crypt is needed
 Library m is needed
Final link with: crypt m
[HongGe@Hzh1024n busybox-1.9.0]$ make install

3)安装glibc库

  在开发板上只需要加载器和动态库，假设要构建的根文件系统目录为/home/work/hzh1024n/rootfs,操作如下：

[HongGe@Hzh1024n busybox-1.9.0]$ cd /usr/local/arm/3.3.2/arm-linux/lib

[HongGe@Hzh1024n lib]$ cp *.so* /home/work/hzh1024n/rootfs/lib -d

上面复制的库文件不是每个都会被用到，可以根据应用程序对库的依赖关系保留需要用到的。通过ldd命令可以查看一个程序会用到哪些库，主机自带的ldd命令不能查看交叉编译出来的程序，有以下两种替代方法。

*如果有uClibc-0.9.28的代码，可以进入utils子目录生成ldd.host工具。

$cd uClibc-0.9.28/utils

$make ldd.host

然后将生成的ldd.host放到主机/usr/local/bin目录下即可

$ldd.host busybox

*也可以使用下面命令

$arm-linux-readelf -a "your binary" | grep "shared"

比如对于动态链接的Busybox，它的库依赖关系如下。

 0x00000001 (NEEDED) Shared library: [libcrypt.so.1]
 0x00000001 (NEEDED) Shared library: [libm.so.6]
 0x00000001 (NEEDED) Shared library: [libc.so.6]


4）修改和创建必要的文件。

 

[HongGe@Hzh1024n busybox-1.9.0]$ cp -a examples/bootfloppy/etc/*

[HongGe@Hzh1024n busybox-1.9.0]$ cd /home/work/hzh1024n/rootfs/etc/

1、增加为SHELL导入全局变量的文件/etc/profile

[HongGe@Hzh1024n 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 (彩色特效)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

[HongGe@Hzh1024n etc]$ kwrite inittab

::sysinit:/etc/init.d/rcS
::restart:/sbin/init
::askfirst:-/bin/sh
::ctrlaltdel:/sbin/reboot
::shutdown:/bin/umount -a -r
::shutdown:/sbin/swapoff -a

 

[HongGe@Hzh1024n etc]$ kwrite fstab

proc  /proc proc defaults    0 0

tmpfs /tmp tmpfs defaults 0 0
sysfs /sys sysfs defaults 0 0
tmpfs /dev tmpfs  defaults 0 0

 

3、增加初始化脚本

[HongGe@Hzh1024n etc]$ kwrite init.d/rcS

#! /bin/sh
ifconfig eth0 192.168.1.67
echo "----------mount all"
/bin/mount -a
/bin/mkdir /dev/pts
echo "----------Starting mdev......"
/bin/mount -t devpts devpts /dev/pts
/bin/echo /sbin/mdev > /proc/sys/kernel/hotplug
mdev -s

echo "*********************************************************"
echo "  HongGe Hzh1024n rootfs    "
echo "   Wellcome  ! !         "
echo "********************************************************"

 

4、删除备份文件

[HongGe@Hzh1024n etc]$ rm *~ init.d/*~

 

5、为mdev创建配置文件

[HongGe@Hzh1024n etc]$ vi mdev.conf

创建一个mdev.conf文件，内容可有可无。

 

到此为止一个基本的根文件系统已经制作成功，下一步是挂载jffs2根文件系统。

如果要以挂载JFFS2格式的根文件系统，其基本方法就是将这个建立好的根文件系统制作成jffs2镜像，烧到FLASH中，改改Linux的启动参数即可。

 

具体做法如下：

一、宿主机HOST编译制做MTD工具

 

从下载mtd-utils 的tarball，可以下载最新的。然后解压，并在其目录下 make 就好！

 

二、制作根文件系统的JFFS2镜像。

 

使用MTD工具中的mkfs.jffs2命令，具体做法如下：

mkfs.jffs2 -r /home/work/hzh1024n/rootfs -o rootfs.jffs2 -e 0x4000 --pad=0x500000 -s 0x200 -n

 

各参数的意义：

(1)-r ： 指定要做成image的源資料夾.
(2)-o : 指定輸出image檔案的文件名.
(3)-e : 每一塊要抹除的block size，預設是64KB.要注意，不同的flash, 其block size會不一樣.我的是三星的K9F1208U0B.
(4)--pad （-p）: 用16進制來表示所要輸出檔案的大小，也就是root.jffs2的size。很重要的是, 為了不浪費flash空間, 這個值最好符合flash driver所規劃的區塊大小.以我的板子來說，就是5MB.
(5)如果挂载后会出现类似：CLEANMARKER node found at 0x0042c000 has totlen 0xc != normal 0x0  的警告，则加上 -n 就会消失。
(6) 还有的选项，自己看帮助！-h

 

三、烧写JFFS2镜像到NAND FLASH。

将 rootfs.jffs2烧写到FLASH中，注意内核挂载文件系统的参数，按照参数把文件系统烧写到相关的位置当中。然后启动开发板。

Uncompressing Linux........................................................................................................ done, booting the kernel.
Linux version 2.6.22.6 (HongGe) (gcc version 3.3.2) #1 Wed Feb 07 11:18:36 CST 2008
CPU: ARM920T [41129200] revision 0 (ARMv4T), cr=c0007177
Machine: Hzh1024n
Memory policy: ECC disabled, Data cache writeback
CPU S3C2440A (id 0x32440001)
S3C244X: core 405.000 MHz, memory 101.250 MHz, peripheral 50.625 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: noinitrd root=/dev/mtdblock4 rootfstype=jffs2 rw console=ttySAC0,115200 init=/linuxrc mem=64M
irq: clearing pending ext status 00000200
irq: clearing subpending status 00000003
irq: clearing subpending status 00000002
PID hash table entries: 256 (order: 8, 1024 bytes)
timer tcon=00500000, tcnt a4ca, tcfg 00000200,00000000, usec 00001e57
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: 61464KB available (2960K code, 306K data, 120K 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
S3C2440: Initialising architecture
S3C2440: IRQ Support
S3C2440: Clock Support, DVS off
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
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.
fuse init (API version 7.9)
yaffs Feb 15 2008 10:10:34 Installing.
io scheduler noop registered
io scheduler anticipatory registered (default)
io scheduler deadline registered
io scheduler cfq registered
Serial: 8250/16550 driver $Revision: 1.90 $ 4 ports, IRQ sharing enabled
s3c2440-uart.0: s3c2410_serial0 at MMIO 0x50000000 (irq = 70) is a S3C2440
s3c2440-uart.1: s3c2410_serial1 at MMIO 0x50004000 (irq = 73) is a S3C2440
s3c2440-uart.2: s3c2410_serial2 at MMIO 0x50008000 (irq = 76) is a S3C2440
RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize
loop: module loaded
dm9000 Ethernet Driver
eth0: dm9000 at f6100300,f6100304 IRQ 51 MAC: 08:08:08:08:12:27
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
s3c2440-nand s3c2440-nand: Tacls=1, 9ns Twrph0=4 39ns, Twrph1=1 9ns
NAND device: Manufacturer ID: 0xec, Chip ID: 0x76 (Samsung NAND 64MiB 3,3V 8-bit)
Scanning device for bad blocks
Bad eraseblock 3579 at 0x037ec000
Creating 7 MTD partitions on "NAND 64MiB 3,3V 8-bit":
0x00000000-0x00020000 : "U-Boot-1.2.0"
0x00020000-0x00030000 : "U-Boot-1.2.0 Parameter"
0x00030000-0x00500000 : "Linux2.6.22.6 Kernel"
0x00500000-0x00a00000 : "Root(cramfs)"
0x00a00000-0x00f00000 : "Root(JFFS2)"
0x00f00000-0x01400000 : "Root(YAFFS)"
0x01400000-0x04000000 : "DATA"
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-rtc s3c2410-rtc: rtc disabled, re-enabling
s3c2410-rtc s3c2410-rtc: rtc core: registered s3c as rtc0
s3c2440-i2c s3c2440-i2c: slave address 0x10
s3c2440-i2c s3c2440-i2c: bus frequency set to 98 KHz
s3c2440-i2c s3c2440-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
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
s3c2410-rtc s3c2410-rtc: setting system clock to 2008-02-17 12:46:08 UTC (1203252368)
VFS: Mounted root (jffs2 filesystem).
Freeing init memory: 120K
init started: BusyBox v1.9.1 (2008-02-16 15:04:08 CST)
starting pid 779, tty '': '/etc/init.d/rcS'
----------mount all
----------Starting mdev......
*********************************************************
  HongGe Hzh1024n rootfs 
     Wellcome  ! ! 

********************************************************
starting pid 783, tty '': '/bin/login'
(none) login: root
Password:
login[783]: root login on 'console'

Processing /etc/profile...
Set search library path in /etc/profile
Set user path in /etc/profile
Set PS1 in /etc/profile
Done

[root@~]#

成功！！！