u-boot/doc/README.ext4

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This patch series adds support for ext4 ls,load and write features in uboot
Journaling is supported for write feature.
To enable support for the ext4 (and ext2) filesystem implementation,
#define CONFIG_FS_EXT4
If you want write support,
#define CONFIG_EXT4_WRITE
To Enable ext2 ls and load commands, modify the board specific config file with
#define CONFIG_CMD_EXT2
This automatically defines CONFIG_FS_EXT4 for you.
To Enable ext4 ls and load commands, modify the board specific config file with
#define CONFIG_CMD_EXT4
This automatically defines CONFIG_FS_EXT4 for you.
To enable ext4 write command, modify the board specific config file with
#define CONFIG_CMD_EXT4
#define CONFIG_CMD_EXT4_WRITE
These automatically define CONFIG_FS_EXT4 and CONFIG_EXT4_WRITE for you.
Also relevant are the generic filesystem commands,
#define CONFIG_CMD_FS_GENERIC
This does not automatically enable EXT4 support for you.
Steps to test:
1. After applying the patch, ext4 specific commands can be seen
in the boot loader prompt using
UBOOT #help
ext4load- load binary file from a Ext4 file system
ext4ls - list files in a directory (default /)
ext4write- create a file in ext4 formatted partition
2. To list the files in ext4 formatted partition, execute
ext4ls <interface> <dev[:part]> [directory]
For example:
UBOOT #ext4ls mmc 0:5 /usr/lib
3. To read and load a file from an ext4 formatted partition to RAM, execute
ext4load <interface> <dev[:part]> [addr] [filename] [bytes]
For example:
UBOOT #ext4load mmc 2:2 0x30007fc0 uImage
4. To write a file to a ext4 formatted partition.
a) First load a file to RAM at a particular address for example 0x30007fc0.
Now execute ext4write command
ext4write <interface> <dev[:part]> [filename] [Address] [sizebytes]
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
References :
-- ext4 implementation in Linux Kernel
-- Uboot existing ext2 load and ls implementation
-- Journaling block device JBD2 implementation in linux Kernel