doc/README.ext4

   1 U-Boot supports access of both ext2 and ext4 filesystems, either in read-only
   2 mode or in read-write mode.
   3
   4 First, to enable support for both ext4 (and, automatically, ext2 as well),
   5 but without selecting the corresponding commands, enable one of the following:
   6
   7   CONFIG_FS_EXT4        (for read-only)
   8   CONFIG_EXT4_WRITE     (for read-write)
   9
  10 Next, to select the ext2-related commands:
  11
  12   * ext2ls
  13   * ext2load
  14
  15 or ext4-related commands:
  16
  17   * ext4size
  18   * ext4ls
  19   * ext4load
  20
  21 use one or both of:
  22
  23   CONFIG_CMD_EXT2
  24   CONFIG_CMD_EXT4
  25
  26 Selecting either of the above automatically selects CONFIG_FS_EXT4 if it
  27 wasn't enabled already.
  28
  29 In addition, to get the write access command "ext4write", enable:
  30
  31   CONFIG_CMD_EXT4_WRITE
  32
  33 which automatically selects CONFIG_EXT4_WRITE if it wasn't defined
  34 already.
  35
  36 Also relevant are the generic filesystem commands, selected by:
  37
  38   CONFIG_CMD_FS_GENERIC
  39
  40 This does not automatically enable EXT4 support for you, you still need
  41 to do that yourself.
  42
  43 Some sample commands to test ext4 support:
  44
  45 1. Check that the commands can be seen in the output of U-Boot help:
  46
  47         UBOOT #help
  48         ...
  49         ext4load- load binary file from a Ext4 file system
  50         ext4ls  - list files in a directory (default /)
  51         ext4size - determine a file's size
  52         ext4write- create a file in ext4 formatted partition
  53         ...
  54
  55 2. To list the files in an ext4-formatted partition, run:
  56
  57         ext4ls <interface> <dev[:part]> [directory]
  58
  59         For example:
  60         UBOOT #ext4ls mmc 0:5 /usr/lib
  61
  62 3. To read and load a file from an ext4-formatted partition to RAM, run:
  63
  64         ext4load <interface> <dev[:part]> [addr] [filename] [bytes]
  65
  66         For example:
  67         UBOOT #ext4load mmc 2:2 0x30007fc0 uImage
  68
  69 4. To write a file to an ext4-formatted partition.
  70
  71         a) First load a file to RAM at a particular address for example 0x30007fc0.
  72         Now execute ext4write command:
  73         ext4write <interface> <dev[:part]> [filename] [Address] [sizebytes]
  74
  75         For example:
  76         UBOOT #ext4write mmc 2:2 /boot/uImage 0x30007fc0 6183120
  77         (here 6183120 is the size of the file to be written)
  78         Note: Absolute path is required for the file to be written
  79
  80 References :
  81         -- ext4 implementation in Linux Kernel
  82         -- Uboot existing ext2 load and ls implementation
  83         -- Journaling block device JBD2 implementation in linux Kernel