嵌入式Linux之我行，主要讲述和总结了本人在学习嵌入式linux中的每个步骤。一为总结经验，二希望能给想入门嵌入式Linux的朋友提供方便。如有错误之处，谢请指正。
一、移植环境
- 主 机：VMWare--Fedora 9
- 开发板：Mini2440--64MB Nand
- 编译器：arm-linux-gcc-4.3.2
- yaffs补丁：cvs-root.tar.gz 这里下载
- Busybox：busybox-1.13.0.tar.tar
- yaffs制作工具：mkyaffs2image.tgz（友善提供）
二、移植步骤
1. 准备工作目录和进入工作目录
2. 给内核打上yaffs补丁，使内核对yaffs的支持
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#tar -zxvf cvs-root.tar.gz
#cd cvs/yaffs2/
#./patch-ker.sh c /root/my2440/linux-2.6.30.4/
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3. 配置内核，使其对yaffs2文件系统的支持。配置完后重新编译内核，下载到开发板上
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File systems --->
< > Second extended fs support
< > Ext3 journalling file system support
< > The Extended 4 (ext4) filesystem
< > Reiserfs support
< > JFS filesystem support
< > XFS filesystem support
< > OCFS2 file system support
< > Btrfs filesystem (EXPERIMENTAL) Unstable disk format
[*] Enable POSIX file locking API
[*] Dnotify support
[*] Inotify file change notification support
[*] Inotify support for userspace
[ ] Quota support
Kernel automounter support
Kernel automounter version 4 support (also supports v3)
FUSE (Filesystem in Userspace) support
Caches --->
CD-ROM/DVD Filesystems --->
<*> ISO 9660 CDROM file system support
[ ] Microsoft Joliet CDROM extensions
[ ] Transparent decompression extension
< > UDF file system support
DOS/FAT/NT Filesystems --->
<*> MSDOS fs support
<*> VFAT (Windows-95) fs support
(437) Default codepage for FAT
(iso8859-1) Default iocharset for FAT
< > NTFS file system support
Pseudo filesystems --->
[*] Miscellaneous filesystems --->
--- Miscellaneous filesystems
< > ADFS file system support (EXPERIMENTAL)
< > Amiga FFS file system support (EXPERIMENTAL)
< > Apple Macintosh file system support (EXPERIMENTAL)
< > Apple Extended HFS file system support
< > BeOS file system (BeFS) support (read only) (EXPERIMENTAL)
< > BFS file system support (EXPERIMENTAL)
< > EFS file system support (read only) (EXPERIMENTAL)
<*> YAFFS2 file system support
-*- 512 byte / page devices
[ ] Use older-style on-NAND data format with pageStatus byte
[ ] Lets Yaffs do its own ECC
-*- 2048 byte (or larger) / page devices
[*] Autoselect yaffs2 format
[ ] Disable lazy loading
[ ] Turn off wide tnodes
[ ] Force chunk erase check
[*] Cache short names in RAM
<*> Journalling Flash File System v2 (JFFS2) support
(0) JFFS2 debugging verbosity (0 = quiet, 2 = noisy)
[*] JFFS2 write-buffering support
[ ] Verify JFFS2 write-buffer reads
[*] JFFS2 summary support (EXPERIMENTAL)
[ ] JFFS2 XATTR support (EXPERIMENTAL)
[ ] Advanced compression options for JFFS2
<*> Compressed ROM file system support (cramfs)
SquashFS 4.0 - Squashed file system support
[ ] Additional option for memory-constrained systems
< > FreeVxFS file system support (VERITAS VxFS(TM) compatible)
< > Minix file system support
< > SonicBlue Optimized MPEG File System support
< > OS/2 HPFS file system support
< > QNX4 file system support (read only)
<*> ROM file system support
RomFS backing stores (Block device-backed ROM file system support) --
< > System V/Xenix/V7/Coherent file system support
< > UFS file system support (read only)
< > NILFS2 file system support (EXPERIMENTAL)
[*] Network File Systems --->
Partition Types --->
-*- Native language support --->
< > Distributed Lock Manager (DLM) --->
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4. 编译busybox生成文件系统所需要的应用程序
1)解压busybox源码，修改Makefile使之编译成ARM平台:
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#tar -jxvf busybox-1.13.0.tar.tar
#cd busybox-1.13.0
#gedit Makefile
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大概164行改成CROSS_COMPILE = arm-linux- ，189行改成ARCH = arm
2)配置busybox选项，下面只列出了要注意的地方，没有列出的默认即可
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Busybox Settings --->
General Configuration --->
Buffer allocation policy (Allocate with Malloc) --->
[*] Show verbose applet usage messages
[*] Store applet usage messages in compressed form
[*] Support --install [-s] to install applet links at runtime
[*] Enable locale support (system needs locale for this to work)
[*] Support for --long-options
[*] Use the devpts filesystem for Unix98 PTYs
[*] Support writing pidfiles
[*] Runtime SUID/SGID configuration via /etc/busybox.conf
[*] Suppress warning message if /etc/busybox.conf is not readable
(/proc/self/exe) Path to BusyBox executable
Build Options --->
[*] Build BusyBox as a static binary (no shared libs)
[*] Build with Large File Support (for accessing files > 2 GB)
Installation Options --->
[ ] Don't use /usr
Applets links (as soft-links) --->
(./_install) BusyBox installation prefix
Busybox Library Tuning --->
(6) Minimum password length
(2) MD5: Trade Bytes for Speed
[*] Faster /proc scanning code (+100 bytes)
[*] Command line editing
(1024) Maximum length of input
[*] vi-style line editing commands
(15) History size
[*] History saving
[*] Tab completion
[*] Fancy shell prompts
(4) Copy buffer size, in kilobytes
[*] Use ioctl names rather than hex values in error messages
[*] Support infiniband HW
Linux Module Utilities --->
(/lib/modules) Default directory containing modules
(modules.dep) Default name of modules.dep
[*] insmod
[*] rmmod
[*] lsmod
[*] modprobe
--- Options common to multiple modutils
[ ] Support version 2.2/2.4 Linux kernels
[*] Support tainted module checking with new kernels
[*] Support for module.aliases file
[*] Support for module.symbols fileLinux System Utilities --->
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3)编译和安装busybox，安装完后会在
busybox-1.13.0/_install/目录下生成：bin、linuxrc、sbin、usr
5. 开始构建文件系统
1)新建一个目录root-2.6.30.4，把busybox-1.13.0/_install/目录下生成：bin、linuxrc、sbin、usr复制过来，并且在该目录下创建文件系统所需要的其他目录
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#mkdir root-2.6.30.4
#cp -rf busybox-1.13.0/_install/* root-2.6.30.4/
#cd root-2.6.30.4/
#mkdir dev etc home lib mnt opt proc tmp var www
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2)向各目录中添加文件系统所需要的目录或文件，没有提到的就不用添加。这里要注意各种文件的权限，建议都改为777，命令：#chmod 777 文件名
"dev"目录，创建两个设备文件：
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#mknod console c 5 1
#mknod null c 1 3
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"etc"目录，创建各种配置文件并向里面添加内容，没有列出的就不用添加：
boa/boa.conf: boa WEB服务器配置文件，暂时为空。
group: 系统用户组配置文件，内容如下：
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root:*:0:
daemon:*:1:
bin:*:2:
sys:*:3:
adm:*:4:
tty:*:5:
disk:*:6:
lp:*:7:lp
mail:*:8:
news:*:9:
uucp:*:10:
proxy:*:13:
kmem:*:15:
dialout:*:20:
fax:*:21:
voice:*:22:
cdrom:*:24:
floppy:*:25:
tape:*:26:
sudo:*:27:
audio:*:29:
ppp:x:99:
500:x:500:plg
501:x:501:fa
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inittab: 系统init进程配置文件，内容如下：
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# /etc/inittab
::sysinit:/etc/init.d/rcS
console::askfirst:-/bin/sh
::ctrlaltdel:/sbin/reboot
::shutdown:/bin/umount -a -r
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mime.types: 暂时为空。
passwd: 系统密码文件，内容如下：
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root::0:0:root:/:/bin/sh
ftp::14:50:FTP User:/var/ftp:
bin:*:1:1:bin:/bin:
daemon:*:2:2:daemon:/sbin:
nobody:*:99:99:Nobody:/:
sky::502:502:Linux User,,,:/home/sky:/bin/sh
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rc.d/init.d/httpd: 内容如下：
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#!/bin/sh
base=boa
# See how we were called.
case "$1" in
start)
/usr/sbin/$base
;;
stop)
pid=`/bin/pidof $base`
if [ -n "$pid" ]; then
kill -9 $pid
fi
;;
esac
exit 0
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sysconfig/HOSTNAME: 主机名称文件，内容如下：
fstab: 系统挂载文件系统列表，内容如下：
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# device mount-point type options dump fsck order
none /proc proc defaults 0 0
none /dev/pts devpts mode=0622 0 0
tmpfs /dev/shm tmpfs defaults 0 0
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init.d/rcS: 系统启动加载项，内容如下：
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#!/bin/sh
PATH=/sbin:/bin:/usr/sbin:/usr/bin
runlevel=S
prevlevel=N
umask 022
export PATH runlevel prevlevel
#
# Trap CTRL-C &c only in this shell so we can interrupt subprocesses.
#
/bin/mount -t proc none /proc
/bin/mount -t tmpfs none /tmp
/bin/mount -t tmpfs none /var
/bin/mkdir -p /var/log
/bin/hostname -F /etc/sysconfig/HOSTNAME
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mdev.conf: mdev设备配置文件，暂时为空。
net.conf: 网络配置文件，暂时为空。
profile: 用户环境配置文件，内容如下：
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# Ash profile
# vim: syntax=sh
# No core files by default
#ulimit -S -c 0 > /dev/null 2>&1
USER="`id -un`"
LOGNAME=$USER
PS1='[\u@\h \W]\# '
PATH=$PATH:/usr/local/bin
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib
HOSTNAME=`/bin/hostname`
export USER LOGNAME PS1 PATH LD_LIBRARY_PATH
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resolv.conf: DNS配置文件，内容如下：
"home"目录：创建一个sky目录，与etc目录passwd文件中的sky相对应
"lib"目录：这个里面放的都是库文件，直接从交叉编译器的库文件目录中拷贝过来：
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#cp -f /usr/local/arm/4.3.2/arm-none-linux-gnueabi/libc/armv4t/lib/*so* lib/ -a
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6. 使用yaffs制作工具编译构建好的文件系统。先解压mkyaffs2image.tgz（这个工具是友善提供的，可以在他们的网站上下载），会自动解压到开发主机的/usr/sbin/目录下。编译后生成的文件系统镜像
root-2.6.30.4.bin也在这个目录下
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#tar -zxvf mkyaffs2image.tgz
#mkyaffs2image root-2.6.30.4/ root-2.6.30.4.bin
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7. 下载文件系统镜像到开发板上测试，使用情况如下：
三、结束语
现在文件系统成功移植上去了，加上上一篇章的内核移植，至此开发板可以运行起来了。但是各种外设还不能正常使用，后续的篇章将逐步移植各种设备的驱动，使之完善。
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