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2012-06-12 14:24:29

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http://www.aleph1.co.uk/cgi-bin/viewcvs.cgi/
  • 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

#mkdir my2440
#cd my2440

2. 给内核打上yaffs补丁,使内核对yaffs的支持

#tar -zxvf cvs-root.tar.gz
#cd cvs/yaffs2/
#./patch-ker.sh c /root/my2440/linux-2.6.30.4/


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

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) --->

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:

#tar -jxvf busybox-1.13.0.tar.tar
#cd busybox-1.13.0
#gedit Makefile

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

#make menuconfig

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 --->


   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

#make
#make install

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

#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

   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:

#mknod console c 5 1
#mknod null c 1 3

"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:

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

inittab: 系统init进程配置文件,内容如下:

# /etc/inittab
::sysinit:/etc/init.d/rcS
console::askfirst:-/bin/sh
::ctrlaltdel:/sbin/reboot
::shutdown:/bin/umount -a -r

mime.types: 暂时为空。

passwd: 系统密码文件,内容如下:

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

rc.d/init.d/httpd: 内容如下:

#!/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

sysconfig/HOSTNAME: 主机名称文件,内容如下:

MY2440

fstab: 系统挂载文件系统列表,内容如下:

# 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

init.d/rcS: 系统启动加载项,内容如下:

#!/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

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:

# 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

resolv.conf: DNS配置文件,内容如下:

nameserver 61.144.56.100


"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:

#cp -f /usr/local/arm/4.3.2/arm-none-linux-gnueabi/libc/armv4t/lib/*so* lib/ -a



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

#tar -zxvf mkyaffs2image.tgz
#mkyaffs2image root-2.6.30.4/ root-2.6.30.4.bin

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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