====== How To Make A SD Image From SD Bootable OS ======

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//__About this Article__//
  * **Author**: sam --- sam@cubietech.com --- 2014/03/13 01:33
  * **Copyrights**: [[http://creativecommons.org/licenses/by-sa/3.0/|CC Attribution-Share Alike 3.0 Unported]]
  * **Contributors**: [[http://cubieboard.org/|Cubieboard Community]] : ...
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===== Abstract =====	 
we may want to backup our SD bootable OS which have installed many application software. We can make SD Bootable OS into a SD card image.here is guide for you.This guide is for Linux platform only.
		 
		 
===== Prerequisites =====	 
   * Any Linux environment,​ we want fdisk, dd, tar,  commands
   * An SD Card which must have installed a OS 
  
		 
==== Steps:====	 



==== (1) Unpacking you  SD card OS.  ====
==== 1.Unpacking the first partition (including script.bin uImag bootscr ) ====
  $sudo umount /media/*
  $sudo mount /dev/sdb1 /mnt    
  $sudo tar -cp * |sudo gzip -9 > ~/bootfs.tar.gz
  $sudo umount /mnt


==== 2.Unpacking the second partion (file systerm) ====

   $sudo mount /dev/sdb2 /mnt
   $sudo tar -cp * |sudo gzip -9 > ~/rootfs.tar.gz


==== (2) Begining making imgae ====
==== 1.Create a empty image and write uboot in it ====

  $ mkdir WORK_DIR
  $cd $WORK_DIR  
  //creating empty image , this space is 2.5G,you can change by yourself
  $sudo dd if=/dev/zero of=disk.img count=5000000    
  //associating /dev/loop0 with the image
  $sudo losetup /dev/loop0 disk.img               
  $sudo dd if=/dev/zero of=/dev/loop0 bs=1k count=1024   
  $sudo dd if=u-boot-sunxi-with-spl.bin of=/dev/loop0 bs=1024 seek=8  //write uboot in image
  
  
==== 2.Partitioning====

  $sudo fdisk /dev/loop0

Using the fdisk command to create 2 partitions on the SD Card, e.g.
  * 1st partitions start from 2048 sectors, 64MB in size
  * 2nd partitions just keep it all default

Show bellow
  
  Device Boot            Start         End      Blocks   Id  System
  /dev/loop0p1            2048      133119       65536   83  Linux
  /dev/loop0p2          133120     4999999     2433440   83  Linu

Also we recommend you to look at [[http://linux-sunxi.org/Bootable_SD_card |Bootable_SD_card]]



		 
==== 3.Mounting the partition and move OS to image ====

  $cd $WORK_DIR
  associateing /dev/loop0 with image again 
  $sudo losetup -d /dev/loop0 && sudo losetup /dev/loop0 disk.img 
  //associateing  /dev/loop1 with the first partition of /dev/loop0,1048576=512*2048)  
  $sudo losetup -o 1048576 /dev/loop1 /dev/loop0            
  //format the first partition
  $sudo mkfs.vfat /dev/loop1  
  //format the second partitions
  $sudo mkfs.ext4 /dev/loop2   
  $sudo mount /dev/loop1 /mnt   
  //decompressing bootfs.tar.gz to the first partition
  $sudo tar -zxvf ~/bootfs.tar.gz -C /mnt  
  $sudo umount /mnt
  $sudo mount /dev/loop2 /mnt  
  //decompressing rootfs.tar.gz to second partition
  $sudo tar -zxvf ~/rootfs.tar.gz -C /mnt 
  $sync && umount /mnt
  //cancel associating
  $losetup -d /dev/loop2  
  //cancel associating
  $losetup -d /dev/loop1   
  //cancel associating
  $losetup -d  /dev/loop0