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doc/README.ext4
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U-Boot supports access of both ext2 and ext4 filesystems, either in read-only mode or in read-write mode. |
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First, to enable support for both ext4 (and, automatically, ext2 as well), |
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but without selecting the corresponding commands, enable one of the following: |
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CONFIG_FS_EXT4 (for read-only) CONFIG_EXT4_WRITE (for read-write) |
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Next, to select the ext2-related commands: |
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* ext2ls * ext2load |
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or ext4-related commands: |
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* ext4size * ext4ls * ext4load |
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use one or both of: |
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CONFIG_CMD_EXT2 CONFIG_CMD_EXT4 |
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Selecting either of the above automatically selects CONFIG_FS_EXT4 if it wasn't enabled already. |
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In addition, to get the write access command "ext4write", enable: |
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CONFIG_CMD_EXT4_WRITE |
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which automatically selects CONFIG_EXT4_WRITE if it wasn't defined |
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already. Also relevant are the generic filesystem commands, selected by: |
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CONFIG_CMD_FS_GENERIC |
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This does not automatically enable EXT4 support for you, you still need to do that yourself. Some sample commands to test ext4 support: |
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1. Check that the commands can be seen in the output of U-Boot help: UBOOT #help ... |
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ext4load- load binary file from a Ext4 file system ext4ls - list files in a directory (default /) |
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ext4size - determine a file's size |
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ext4write- create a file in ext4 formatted partition |
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... 2. To list the files in an ext4-formatted partition, run: |
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ext4ls <interface> <dev[:part]> [directory] |
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For example: UBOOT #ext4ls mmc 0:5 /usr/lib |
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3. To read and load a file from an ext4-formatted partition to RAM, run: |
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ext4load <interface> <dev[:part]> [addr] [filename] [bytes] |
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For example: UBOOT #ext4load mmc 2:2 0x30007fc0 uImage |
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4. To write a file to an ext4-formatted partition. |
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a) First load a file to RAM at a particular address for example 0x30007fc0. |
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Now execute ext4write command: |
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ext4write <interface> <dev[:part]> [filename] [Address] [sizebytes] |
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For example: UBOOT #ext4write mmc 2:2 /boot/uImage 0x30007fc0 6183120 (here 6183120 is the size of the file to be written) Note: Absolute path is required for the file to be written |
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References : -- ext4 implementation in Linux Kernel -- Uboot existing ext2 load and ls implementation -- Journaling block device JBD2 implementation in linux Kernel |