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