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最初是想把整个ubuntu移植到MX51开发板，因为项目不需要运行桌面系统，所以只移植了一个基本的ubuntu core系统

 1. 下载ubuntu core rootfs，关于ubuntu core参考https://wiki.ubuntu.com/Core

http://cdimage.ubuntu.com/ubuntu-core/releases/12.04/release/ubuntu-core-12.04.3-core-armhf.tar.gz

这个镜像就是一个rootfs，可以作为根文件系统使用。


2. 把镜像烧写到开发板的一个分区上

    • adb shell进入开发板，busybox mkfs.ext2 /dev/block/mmcblk0p1
• adb shell进入开发板，mount -t ext2 /dev/block/mmcblk0p1 /mnt
• adb push ubuntu-core-12.04.3-core-armhf.tar.gz /mnt/
• adb shell进入开发板，cd /mnt; busybox tar ubuntu-core-12.04.3-core-armhf.tar.gz. 在/dev/block/mmcblk0p1这个分区上建立了一个完整的rootfs，文件系统类型为ext2

    3. 我的arm开发板是mx51，修改uboot启动参数如下：

    set bootargs_android 'setenv bootargs ${bootargs_base} init=/init rdinit=asdf root=b301 rootfs=ext2 di0_primary video=mxcdi0fb:RGB24,CLAA-WVGA'

    粗体是我增加的参数，解释下增加的几个参数：

    • rdinit=asdf，rdinit=后的asdf是胡乱写的，这样会设置ramdisk_execute_command为asdf，就导致内核代码


      [cpp] view plain copy
      1. if (sys_access((const char
2.  sys_access访问失败，调用prepare_namespace 从mmcblk0p1安装根文件系统
• root=b301，是/dev/block/mmcblk0p1的16进制主设备号b3和从设备号01
• rootfs=ext2，文件系统类
      • 型

      4. 启动开发板，会打印出如下信息：


      [cpp] view plain copy 


      1. VFS: Mounted root (ext2 filesystem) on device 179:1.


      表示已经mount 根文件系统成功。

      这一步可能会出现如下错误：


      [cpp] view plain copy 

      1. udevd[123]: unable to receive ctrl connection: Function not implemented  
2. udevd[123]: unable to receive ctrl connection: Function not implemented  
3. udevd[123]: unable to receive ctrl connection: Function not implemented  
4. udevd[123]: unable to receive ctrl connection: Function not implemented  
5. udevd[123]: unable to receive ctrl connection: Function not implemented  
6. udevd[123]: unable to receive ctrl connection: Function not implemented

      如果你出现了，那么执行第5步


      5. 按链接给的patch, 修改内核

      https://github.com/genesi/Linux-legacy/commit/a84fac75f38de592e530a2f9f982d7aafec6c288


      6. 编译内核并烧写到开发板上，重启系统后，不会再打印step4的错误


      7. 支持LCD console，修改内核配置文件如下


      [cpp] view plain copy 


      1. @@ -1228,8 +1228,14 @@ CONFIG_FB_MXC_SYNC_PANEL=y  
2.  # Console display driver support
3.  #
4.  # CONFIG_VGA_CONSOLE is not set
5. +# CONFIG_VGACON_SOFT_SCROLLBACK is not set  
6.  CONFIG_DUMMY_CONSOLE=y  
7. -# CONFIG_FRAMEBUFFER_CONSOLE is not set  
8. +CONFIG_FRAMEBUFFER_CONSOLE=y  
9. +# CONFIG_FRAMEBUFFER_CONSOLE_DETECT_PRIMARY is not set  
10. +# CONFIG_FRAMEBUFFER_CONSOLE_ROTATION is not set  
11. +# CONFIG_FONTS is not set  
12. +CONFIG_FONT_8x8=y  
13. +CONFIG_FONT_8x16=y


      重新编译内核，重启系统后，可在LCD看到ubuntu的登录console


      8 支持serial console，我的开发板没有usbhost，不能接usb键盘，所以需要用serial console控制

      1. # console - getty
2. #
3. # This service maintains a getty on console from the point the system is
4. # started until it is shut down again.
5.   
6. start on stopped rc RUNLEVEL=[2345] and container CONTAINER=lxc  
7.   
8. stop on runlevel [!2345]  
9.   
10. respawn  
11. exec /sbin/getty -L 115200 ttymxc0 vt102
      1. #!/bin/sh -e
2. #
3. # rc.local
4. #
5. # This script is executed at the end of each multiuser runlevel.
6. # Make sure that the script will "exit 0" on success or any other
7. # value on error.
8. #
9. # In order to enable or disable this script just change the execution
10. # bits.
11. #
12. # By default this script does nothing.
13. start ttymxc0  
14. exit 0

      重新启动后，即可在串口得到控制台信息。