config FS_EXT4 bool "Enable ext4 filesystem support" help This provides support for reading images from the ext4 filesystem. ext4 is a widely used general-purpose filesystem for Linux. You can also enable CMD_EXT4 to get access to ext4 commands. config EXT4_WRITE bool "Enable ext4 filesystem write support" depends on FS_EXT4 help This provides support for creating and writing new files to an existing ext4 filesystem partition.