How to create a bootable img file

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Post Last Edited by popboy126 at 2014-5-9 01:50

Post Last Edited by popboy126 at 2014-5-9 01:43

There are two ways to create a bootable img file.
1. Simply using dd command create img file from sd card.
  1. sudo dd if=/dev/sdx of=your_img_file_path bs=xxx
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you can get the device node by using
  1. sudo fdisk -l
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in the screenshot, the device node is sdb, so the command sdx should be replaced by sdb.
bs is the optional parameter which can speed up the coping velocity. but bs should be integral multiple of 512 bytes.

2. Using series of command to specify a image.
     A. using dd command to create a image of defined size.
  1. dd if=/dev/zero of=/tmp/xxx.img bs=1M count=4000
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/tmp/xxx.img is the path of image file you want to create
          bs=1M and count =4000 specify the size of the image. you can refer to the help of dd to find more infomation about these two parameters.
 B. using losetup command to load the image.
  1. sudo losetup /dev/loop0 /tmp/xxx.img
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C. using fdisk to create partitions
  1. sudo fdisk /dev/loop0
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Follow the picture to create the first partition.
        and the second partition can be created by following the same steps.
  Then hit “w” to save the partition information and exit.
  D. using kpartx command to load the partition information.
  1. sudo kpartx -av /dev/loop0
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We can see the partition information after we input this command
  E. Format the partitions.
  1. sudo mkfs -t XXX /dev/mapper/loop0pX
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  F. dd uboot
  1. sudo dd if=uboot-with-spl.bin of=/dev/loop0 bs=1024 seek=8
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  G. Mount partitions and copy files
  1. sudo mount /dev/mapper/loop0pX /mnt
  2.   sudo cp -av XXX /mnt
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H. After copy the files you need, then umount the image.
  1. sudo kpartx -d /dev/loop0
  2.   sudo losetup -d /dev/loop0
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I. The bootable image is done!
It is very useful!

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