The UBIFS volume can be mounted using the Linux UBIFS driver.

Create a mount point and mount the volume.

root@j721s2-evm:~# mkdir -p /mnt/ospi_rootfs
root@j721s2-evm:~# mount -t ubifs -o compr=none ubi0:rootfs /mnt/ospi_rootfs
[  378.881540] UBIFS (ubi0:0): default file-system created
[  378.886938] UBIFS (ubi0:0): Mounting in unauthenticated mode
[  378.892793] UBIFS (ubi0:0): background thread "ubifs_bgt0_0" started, PID 1188
[  378.924191] UBIFS (ubi0:0): UBIFS: mounted UBI device 0, volume 0, name "rootfs"
[  378.931604] UBIFS (ubi0:0): LEB size: 262016 bytes (255 KiB), min./max. I/O unit sizes: 16 bytes/256 bytes
[  378.941248] UBIFS (ubi0:0): FS size: 54761344 bytes (52 MiB, 209 LEBs), max 219 LEBs, journal size 2620160 bytes (2 MiB, 10 LEBs)
[  378.952889] UBIFS (ubi0:0): reserved for root: 2586513 bytes (2525 KiB)
[  378.959495] UBIFS (ubi0:0): media format: w5/r0 (latest is w5/r0), UUID 0D0FF060-F89F-4D12-B474-1C6AA3288A8D, small LPT model
root@j721s2-evm:~#

The mounted filesystem can be verified using standard Linux file operations.

For example,

root@j721s2-evm:~# echo hello > /mnt/ospi_rootfs/test.txt
root@j721s2-evm:~# sync
root@j721s2-evm:~# cat /mnt/ospi_rootfs/test.txt
hello
root@j721s2-evm:~#

In addition to verification on Linux, the UBIFS volume can be also verified from the U-Boot environment. This step ensures that the filesystem created in Linux can be accessed by U-Boot before storing Linux boot artifacts.

The following commands were used.

=> ubi part ospi.rootfs

=> ubifsmount ubi0:rootfs

=> ubifsls /

Example output is below.

=> ubi part ospi.rootfs
k3-navss-ringacc ringacc@2b800000: Ring Accelerator probed rings:286, gp-rings[96,20] sci-dev-id:272
k3-navss-ringacc ringacc@2b800000: dma-ring-reset-quirk: disabled
jedec_spi_nor flash@0: non-uniform erase sector maps are not supported yet.
cadence_spi spi@47040000: Pattern not found. Skipping calibration
SF: Detected s28hs512t with page size 256 Bytes, erase size 256 KiB, total 64 MiB
jedec_spi_nor flash@0: Software reset enable failed: -524
cadence_spi spi@47050000: Pattern not found. Skipping calibration
SF: Detected mt25qu512a with page size 256 Bytes, erase size 64 KiB, total 64 MiB
Could not find a valid device for spi-nand0
ubi0: attaching mtd7
ubi0: scanning is finished
ubi0: attached mtd7 (name "ospi.rootfs", size 55 MiB)
ubi0: PEB size: 262144 bytes (256 KiB), LEB size: 262016 bytes
ubi0: min./max. I/O unit sizes: 16/256, sub-page size 16
ubi0: VID header offset: 64 (aligned 64), data offset: 128
ubi0: good PEBs: 223, bad PEBs: 0, corrupted PEBs: 0
ubi0: user volume: 1, internal volumes: 1, max. volumes count: 128
ubi0: max/mean erase counter: 7/3, WL threshold: 4096, image sequence number: 1854191452
ubi0: available PEBs: 0, total reserved PEBs: 223, PEBs reserved for bad PEB handling: 0
=> ubifsmount ubi0:rootfs
UBIFS (ubi0:0): recovery needed
UBIFS (ubi0:0): recovery deferred
UBIFS (ubi0:0): UBIFS: mounted UBI device 0, volume 0, name "rootfs", R/O mode
UBIFS (ubi0:0): LEB size: 262016 bytes (255 KiB), min./max. I/O unit sizes: 16 bytes/256 bytes
UBIFS (ubi0:0): FS size: 54761344 bytes (52 MiB, 209 LEBs), journal size 2620160 bytes (2 MiB, 10 LEBs)
UBIFS (ubi0:0): reserved for root: 2586513 bytes (2525 KiB)
UBIFS (ubi0:0): media format: w5/r0 (latest is w4/r0), UUID 0D0FF060-F89F-4D12-B474-1C6AA3288A8D, small LPT model
=> ubifsls /
                6  Fri May 30 02:46:03 2025  test.txt
=>

The successful execution of these commands confirms that the UBI metadata and UBIFS volume created in Linux are recognized correctly by U-Boot and can be accessed before Linux boot files are stored.

Successful read and write operations confirm below.

• The OSPI NOR flash partition is accessible.

• The UBI device is functioning correctly.

• The UBIFS volume can be mounted and used from both Linux and U-Boot environments.

At this point, the rootfs volume is ready to store the Linux kernel image, DTB, and root filesystem components described in the next chapter.