手工构建最简化的/dev目录
利用udev构建完整的/dev目录
利用交叉编译工具链，构建/lib目录
手工构建/etc目录
编译／安装busybox，生成/bin、/sbin、/usr/bin、/usr/sbin目录
配置系统自动生成/proc目录
创建其它空目录
1.根文件系统树制作
在/opt/下新建文件夹rootfs
[luminqi@localhost opt]$ mkdir rootfs
[luminqi@localhost opt]$ cd rootfs
[luminqi@localhost rootfs]$ mkdir -p {apps,bin,data,dev,info,proc,root,sbin,sys,tmp,var,etc/{,init.d,dropbear},mnt/{,usb,sdc,nfs,dev},usr/{,bin,sbin,lib,share},lib/{,modules/{,3.0.0}}}
[luminqi@localhost rootfs]$ tree -L 3
.
├── apps #挂载Application所在分区用的目录
├── bin #必备的用户命令，例如ls、cp等
├── data #挂载data分区所在的目录
├── dev #设备文件，例如mtdblock0
├── etc #系统配置文件，包括启动文件，例如inittab等
│?? ├── dropbear #dropbear ssh server依赖的文件
│?? └── init.d #系统启动初始化脚本
├── info #挂载info分区所在的目录
├── lib #动态库所存放的目录
│?? └── modules #insmod时，依赖/lib/modules/内核版本目录
│?? └── 3.0.0 #我们将Linux驱动放到该目录下，目录名对应内核版本号
├── mnt #设备在运行时的一些挂载点
│?? ├── dev #保留备用
│?? ├── nfs #NFS挂载点
│?? ├── sdc #SD卡挂载点
│?? └── usb #U盘挂载点
├── proc #proc文件挂载点,用来提供内核与进程信息的虚拟文件系统，由内核自动生成目录下的内容
├── root #root用户目录
├── sbin #必备的系统管理员命令，例如ifconfig、reboot等
├── sys #sys文件系统挂载点,用来提供内核与设备信息的虚拟文件系统，由内核自动生成目录下的内容
├── tmp #tmpfs文件系统挂载点,临时性的文件，重启后将自动清除
├── usr
│?? ├── bin #非必备的用户程序，例如find、du等
│?? ├── lib #用户程序动态库放到这里
│?? ├── sbin #非必备的管理员程序
│?? └── share
└── var #守护程序和工具程序所存放的可变，例如日志文件
27 directories, 0 files
因为内核挂载完文件系统后，init进程需要用到/dev/console和/dev/null这两个设备文件来调用mdev构建dev，所以必须在制作文件系统时静态创建这两个设备文件，否则在系统启动时将提示
Waring：unable to open an initial console:
[luminqi@localhost rootfs]$ sudo mknod -m666 dev/null c 1 3 #空设备通常被用于丢弃不需要的输出流，或作为用于输入流的空文件 [luminqi@localhost rootfs]$ sudo mknod -m666 dev/console c 5 1 #系统控制终端，系统的错误信息什么的都输出到这里 [luminqi@localhost rootfs]$ sudo mknod -m666 dev/ttyS0 c 4 64 #串行端口终端,是使用计算机串行端口连接的终端设备。 [luminqi@localhost rootfs]$ sudo mknod -m666 dev/ttySAC0 c 4 64 #串口驱动设备文件 [luminqi@localhost rootfs]$ sudo mknod dev/mtdblock0 b 31 0 #mtd块设备 [luminqi@localhost rootfs]$ sudo mknod dev/mtdblock1 b 31 1 #mtd块设备 [luminqi@localhost rootfs]$ sudo mknod dev/mtdblock2 b 31 2 #mtd块设备 [luminqi@localhost rootfs]$ sudo mknod dev/mtdblock3 b 31 3 #mtd块设备 [luminqi@localhost rootfs]$ sudo mknod dev/mtdblock4 b 31 4 #mtd块设备
3.Var目录下创建符号链接文件
[luminqi@localhost rootfs]$ ln -s /tmp var/lock [luminqi@localhost rootfs]$ ln -s /tmp var/log [luminqi@localhost rootfs]$ ln -s /tmp var/run [luminqi@localhost rootfs]$ ln -s /tmp var/tmp
[luminqi@localhost rootfs]$ cp -af /opt/buildroot-2011.02/arm920t/usr/arm-linux/sysroot/lib/*so* lib/ [luminqi@localhost rootfs]$ cp -af /opt/buildroot-2011.02/arm920t/usr/arm-linux/lib/*so* lib/
5.1创建inittab文件
[luminqi@localhost rootfs]$ cd etc/ [luminqi@localhost etc]$ vim inittab # /etc/inittab # # Copyright (C) 2017 lulinux <lulinux@gmail.com> # # Note: BusyBox init doesn't support runlevels. The runlevels field is # completely ignored by BusyBox init. If you want runlevels, use sysvinit. # # Format for each entry: <id>:<runlevels>:<action>:<process> # # id == tty to run on, or empty for /dev/console. # If specified, then /dev/$id device must exist # runlevels == ignored, busybox doesn't support it # action == one of sysinit, respawn, askfirst, wait, and once # process == program to run # Startup the system # mount all the file systems specified in /etc/fstab ::sysinit:/bin/mount -a #Use mdev as hotplug to auto mount USB storage or SD card ::sysinit:/bin/echo /sbin/mdev > /proc/sys/kernel/hotplug #Use mdev to auto generate the device node in /dev path ::sysinit:/sbin/mdev -s #make shm, pts support ::sysinit:/bin/mkdir -p /dev/pts ::sysinit:/bin/mkdir -p /dev/shm ::sysinit:/bin/mount -t devpts devpts /dev/pts #Mount our apps/data partition null::wait:/bin/mount -o sync,noatime,ro -t jffs2 /dev/mtdblock3 /apps null::wait:/bin/mount -o sync,noatime,ro -t jffs2 /dev/mtdblock4 /data #Set hostname null::sysinit:/bin/hostname -F /etc/hostname #Enable console logon null::respawn:/sbin/getty -L ttyS0 115200 vt100 # now run any rc scripts null::wait:/etc/init.d/rcS # system daemon null::respawn:/sbin/syslogd -n null::respawn:/sbin/klogd -n # Stuff to do before rebooting null::shutdown:/bin/umount /apps null::shutdown:/bin/umount /data null::shutdown:/bin/killall klogd null::shutdown:/bin/killall syslogd null::shutdown:/bin/umount -a -r #null::shutdown:/sbin/swapoff -a
5.2创建/etc/init.d/rcS脚本
[luminqi@localhost etc]$ vim init.d/rcS
#!/bin/sh
# Copyright (C) 2017 lulinux <lulinux@gmail.com>
# Start all init scripts in /etc/init.d
# executing them in numerical order.
#
for i in /etc/init.d/S??* ; do
$i
done
5.3配置网卡的启动脚本
[luminqi@localhost etc]$ vim init.d/S01_network #!/bin/sh ifconfig eth0 192.168.1.111 netmask 255.255.255.0 up
[luminqi@localhost etc]$ vim init.d/S99_rcsApp
#!/bin/sh
# Copyright (C) 2017 lulinux <lulinux@gmail.com>
#
# Start all init scripts in /apps/etc/init.d
# executing them in numerical order.
#
if (test -d /apps/etc/init.d)
then
for i in /apps/etc/init.d/S??* ; do
$i
done
fi
[luminqi@localhost etc]$ chmod 777 init.d/*
5.6创建fstab文件
[luminqi@localhost etc]$ vim fstab # /etc/fstab: static file system information. # Copyright (C) 2017 lulinux <lulinux@gmail.com> # #<File system> <mount pt> <type> <options> <dump> <pass> #devpts /dev/pts devpts defaults 0 0 #/dev/root / ext2 rw,noauto 0 1 proc /proc proc defaults 0 0 tmpfs /tmp tmpfs defaults 0 0 tmpfs /dev tmpfs defaults 0 0 sysfs /sys sysfs defaults 0 0
[luminqi@localhost etc]$ echo "root" > hostname [luminqi@localhost etc]$ echo "127.0.0.1 localhost" >> hosts [luminqi@localhost etc]$ echo "MST7MDT" >> TZ [luminqi@localhost etc]$ echo "Copyright (C) 2017 linux<linux@gmail.com>" >> issue # 系统登录时的提示信息5.8创建profile文件
[luminqi@localhost etc]$ vim profile
# /etc/profile: system-wide .profile file for the Bourne shells.
export PATH=\
/bin:\
/sbin:\
/usr/bin:\
/usr/sbin:\
/usr/local/bin:\
/apps/bin:\
/apps/tools:\
/apps/tslib/bin\
# If running interactively, then:
if [ "$PS1" ]; then
if [ "$BASH" ]; then
export PS1="[\u@\h \W]\\$ "
alias ll='/bin/ls --color=tty -laFh'
alias ls='/bin/ls --color=tty -F'
export LS_COLORS='no=00:fi=00:di=01;34:ln=01;36:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:ex=01;
32:*.tar=01;31:*.tgz=01;31:*.arj=01;31:*.taz=01;31:*.lzh=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.gz=01;31:*.bz2=01;31:*.deb=0
1;31:*.rpm=01;31:*.jar=01;31:*.jpg=01;35:*.jpeg=01;35:*.png=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35
:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.mpg=01;35:*.mpeg=01;35:*.avi=01;35:*.fli=01;35:*.gl=01;35:*.d
l=01;35:*.xcf=01;35:*.xwd=01;35:';
else
if [ "`id -u`" -eq 0 ]; then
export PS1='>: '
else
export PS1='>: '
fi
fi
# System Setting
set -o vi
alias ll='ls -l'
export USER=`id -un`
export LOGNAME=$USER
export HOSTNAME=`/bin/hostname`
export HISTSIZE=1000
export HISTFILESIZE=1000
export PAGER='/bin/more '
export EDITOR='/bin/vi'
export INPUTRC=/etc/inputrc
export DMALLOC_OPTIONS=debug=0x34f47d83,inter=100,log=logfile
export VAR1=
export VAR2=
export VAR3=
export VAR4=
export VAR5=
export LD_LIBRARY_PATH=/lib:/usr/lib/
# QT Extendded 4.4.3 Setting
export QTDIR=/apps/qt-extended-4.4.3
export QWS_MOUSE_PROTO='TSLIB:/dev/event0'
export QWS_DISPLAY='LinuxFB:/dev/fb0'
export QWS_DISPLAY='LinuxFB:mmWidth240:mmHeight320:0'
export QWS_SIZE='240x320'
export QT_PLUGIN_PATH=$QTDIR/plugins/
export QT_QWS_FONTDIR=$QTDIR/lib/fonts
export PATH=$QTDIR/bin:$PATH
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$QTDIR/lib
# Touch Scree tslib Setting
export TSLIB_ROOT=/apps/tslib
export TSLIB_CONFFILE=$TSLIB_ROOT/etc/ts.conf
export TSLIB_CALIBFILE=$TSLIB_ROOT/etc/pointercal
export TSLIB_TSDEVICE=/dev/event0
export TSLIB_CONSOLEDEVICE=none
export TSLIB_FBDEVICE=/dev/fb0
fi;
5.9创建指定一些协议所使用的端口号文件protocols
[luminqi@localhost etc]$ vim protocols # /etc/protocols: # $Id: protocols,v 1.1.1.1 2001/09/12 19:03:24 andersee Exp $ # # Internet (IP) protocols # # from: @(#)protocols 5.1 (Berkeley) 4/17/89 # # Updated for NetBSD based on RFC 1340, Assigned Numbers (July 1992). ip 0 IP # internet protocol, pseudo protocol number icmp 1 ICMP # internet control message protocol igmp 2 IGMP # Internet Group Management ggp 3 GGP # gateway-gateway protocol ipencap 4 IP-ENCAP # IP encapsulated in IP (officially ``IP'') st 5 ST # ST datagram mode tcp 6 TCP # transmission control protocol egp 8 EGP # exterior gateway protocol pup 12 PUP # PARC universal packet protocol udp 17 UDP # user datagram protocol hmp 20 HMP # host monitoring protocol xns-idp 22 XNS-IDP # Xerox NS IDP rdp 27 RDP # "reliable datagram" protocol iso-tp4 29 ISO-TP4 # ISO Transport Protocol class 4 xtp 36 XTP # Xpress Tranfer Protocol ddp 37 DDP # Datagram Delivery Protocol idpr-cmtp 39 IDPR-CMTP # IDPR Control Message Transport rspf 73 RSPF #Radio Shortest Path First. vmtp 81 VMTP # Versatile Message Transport ospf 89 OSPFIGP # Open Shortest Path First IGP ipip 94 IPIP # Yet Another IP encapsulation encap 98 ENCAP # Yet Another IP encapsulation5.10创建mdev.conf文件
mdev会在/etc目录下找mdev的配置文件: mdev.conf. 如果该文件不存在，那么在执行mdev -s这个命令时，会提示找不到mdev.conf，这时我们可以建一个空的mdev.conf文件解决这个问题。下面创建使用mdev自动挂载u盘和SD卡的配置/etc/mdev.conf
[luminqi@localhost etc]$ vim mdev.conf sd[a-z][0-9] 0:0 0777 @(mount /dev/$MDEV /mnt/usb) sd[a-z] 0:0 0777 $(umount /mnt/usb) ub[a-z][0-9] 0:0 0777 @(mount /dev/$MDEV /mnt/usb) ub[a-z] 0:0 0777 $(umount /mnt/usb) mmcblk[0-9]p[0-9] 0:0 0777 @(mount /dev/$MDEV /mnt/sdc) mmcblk[0-9] 0:0 0777 $(umount /mnt/sdc)
5.11创建用户组group文件
[luminqi@localhost etc]$ vim group
root:x:0:root
5.12创建用户passwd文件,这里我们设置为不用密码登陆
[luminqi@localhost etc]$ vim passwad
root::0:0:99999:7:::
5.13创建密码映射shadow文件
[luminqi@localhost etc]$ vim shadow
root:($jGZIHmtT$y8ZXoPllK12/wl51kMw4e/:0:0:99999:7:::)
6.在文件系统中安装busybox
[luminqi@localhost etc] cd /opt
[luminqi@localhost opt]$ ls rootfs
apps bin data dev etc info lib mnt proc root sbin sys tmp usr var
[luminqi@localhost opt] sudo tar -xjf /opt/busybox-1.20.2.tar.bz2 //事先准备好的源码包
[luminqi@localhost opt] cd busybox-1.20.2
[luminqi@localhost busybox-1.20.2]$ vim Makefile
#修改CROSS_COMPILER为：
CROSS_COMPILE ?= /opt/buildroot-2012.08/arm920t/usr/bin/arm-linux-
[luminqi@localhost busybox-1.20.2]$ vt100
[luminqi@localhost busybox-1.20.2]$ sudo make menuconfig
Busybox Settings --->
General Configuration --->
[*] Don't use /usr
Installation Options ("make install" behavior) --->
What kind of applet links to install (as soft-links) ---> //安装busybox时将各个命令安装为指向busybox的软链接
(/opt/rootfs) BusyBox installation prefix
[luminqi@localhost busybox-1.20.2]$ sudo make
[luminqi@localhost busybox-1.20.2]$ file busybox
busybox: ELF 32-bit LSB executable, ARM, version 1 (SYSV), statically linked, stripped
[luminqi@localhost busybox-1.20.2]$ sudo make install
[luminqi@localhost busybox-1.20.2]$ ls /opt/rootfs
apps bin data dev etc info lib linuxrc mnt proc root sbin sys tmp usr var
##仔细看多了一个linuxrc文件
linuxrc -> bin/busybox
7.移植dropbear
7.1首先编译生成PC版的，在制作密钥时用到
[luminqi@localhost busybox-1.20.2]$ cd /home/luminqi/fl2440/3rdparty [luminqi@localhost 3rdparty]$ wget http://matt.ucc.asn.au/dropbear/releases/dropbear-0.53.1.tar.bz2 [luminqi@localhost 3rdparty]$ tar -xjf dropbear-0.53.1.tar.bz2 [luminqi@localhost 3rdparty]$ cd dropbear-0.53.1 [luminqi@localhost dropbear-0.53.1]$ ./configure && make [luminqi@localhost dropbear-0.53.1]$ ./dropbearkey -t rsa -f /opt/rootfs/etc/dropbear/dropbear_rsa_host_key [luminqi@localhost dropbear-0.53.1]$ ./dropbearkey -t dss -f /opt/rootfs/etc/dropbear/dropbear_dss_host_key [luminqi@localhost dropbear-0.53.1]$ chmod 666 /opt/rootfs/etc/dropbear/dropbear_*
7.2编译ARM版本的
[luminqi@localhost dropbear-0.53.1]$ make distclean [luminqi@localhost dropbear-0.53.1]$ ./configure CC=/opt/buildroot-2012.08/arm920t/usr/bin/arm-linux-gcc --build=i686 --host=arm-linux --disable-zlib [luminqi@localhost dropbear-0.53.1]$ make [luminqi@localhost dropbear-0.53.1]$ file dropbear dropbear: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), not stripped [luminqi@localhost dropbear-0.53.1]$ file dbclient dbclient: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), not stripped [luminqi@localhost dropbear-0.53.1]$ mv dbclient ssh [luminqi@localhost dropbear-0.53.1]$ arm-linux-strip dropbear [luminqi@localhost dropbear-0.53.1]$ arm-linux-strip ssh [luminqi@localhost dropbear-0.53.1]$ cp dropbear ssh /opt/rootfs/usr/sbin/
[luminqi@localhost rootfs]$ ll
总用量 60
drwxrwxr-x. 2 luminqi luminqi 4096 3月 3 23:17 apps
drwxrwxr-x. 2 luminqi luminqi 4096 3月 4 00:29 bin
drwxrwxr-x. 2 luminqi luminqi 4096 3月 3 23:17 data
drwxrwxr-x. 2 luminqi luminqi 4096 3月 3 23:20 dev
drwxrwxr-x. 4 luminqi luminqi 4096 3月 4 14:52 etc
drwxrwxr-x. 2 luminqi luminqi 4096 3月 3 23:17 info
drwxrwxr-x. 3 luminqi luminqi 4096 3月 3 23:24 lib
lrwxrwxrwx. 1 root root 11 3月 4 00:29 linuxrc -> bin/busybox
drwxrwxr-x. 6 luminqi luminqi 4096 3月 3 23:17 mnt
drwxrwxr-x. 2 luminqi luminqi 4096 3月 3 23:17 proc
drwxrwxr-x. 2 luminqi luminqi 4096 3月 3 23:17 root
drwxrwxr-x. 2 luminqi luminqi 4096 3月 4 00:29 sbin
drwxrwxr-x. 2 luminqi luminqi 4096 3月 3 23:17 sys
drwxrwxr-x. 2 luminqi luminqi 4096 3月 3 23:17 tmp
drwxrwxr-x. 6 luminqi luminqi 4096 3月 3 23:17 usr
drwxrwxr-x. 2 luminqi luminqi 4096 3月 3 23:21 var
8.在文件系统中创建启动脚本
[luminqi@localhost roorfs]$ cd /opt/rootfs [luminqi@localhost rootfs]$ vim etc/init.d/S04_dropbear #!/bin/sh /usr/sbin/dropbear chmod 777 etc/init.d/S04_dropbear
到这里根文件系统制作完成，但是此时是一个文件夹，我们无法烧写到开发板的nandflash上，要对它进行“ 打包”，做成映像文件的形式。
例如：
制作Initramfs文件系统，原理：上面制成的根文件系统（rootfs这个文件夹）在编译内核的同时被编译并与内核生成一个映像文件（cpio包格式），这种系统是基于RAM（内存）的，它的挂载点在内存中，而不是在nandflash.
制作jffs2文件系统，原理：通过工具mkfs.jffs2将根文件系统（rootfs这个文件夹）制作成映像文件，这种系统是基于flash的，由MTD管理，下面显示了jffs2映像文件的类型：
[luminqi@localhost opt]$ file rootfs.jffs2 rootfs.jffs2: Linux jffs2 filesystem data little endian对于根文件系统和文件系统，我觉得可以这样理解：
根文件系统是最起码能使操作系统跑起来的必须文件的集合，比如/bin、/sbin下的命令文件，还有/etc下的一些配置文件、启动文件inittab等等,如果缺了某一个关键文件，就不能成为根文件系统，Linux内核不承认这种文件系统，导致报错而退出，挂载失败。
赋予根文件系统不同属性，根文件系统就变成了不同的文件系统：
比如赋予根文件系统jffs2的属性（通过工具mkfs.jffs2）,便生成了jffs2文件系统.