Jetson TX2 NX mounts NVME as rootfs despite extlinux.conf setting

Robotics & Edge Computing Jetson & Embedded Systems Jetson TX2
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Hi, I am a newbie in Jetson development. I just got a wheeled robot with a Jetson TX2 NX card (4GB) with an NVME SSD.

After boot, the Jetson mounts the NVME SSD as rootfs, despite the fact that the /boot/extlinux/extlinux.conf configuration file specifies the eMMC as rootfs:

APPEND ${cbootargs} root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4 console=ttyS0,115200n8 console=tty0 fbcon=map:0 net.ifnames=0

In order to repair the NVME file system with fsck, I need to mount another rootfs (for example the eMMC), but I don’t seem to be able to do that just with the extlinux.conf setting. (This would be also useful for making a clone of the NVME file system, after unmounting it).

Normally, I would physically remove the NVME SSD card, but this is difficult, since it would require dismantling the robot.

I made a log of the boot sequence using an UART console (attached in full) – it seems that the eMMC is initially correctly mounted as rootfs (as instructed in extlinux.conf – lines 1258-1266), but later on, it is remounted to /media/jetson/EMMC6 and the NVME is mounted as rootfs.

Line 1258:[ 6.123422] Root device found: mmcblk0p1

Line 1264:[ 6.168728] Found dev node: /dev/mmcblk0p1

Line 1265:[ 6.193567] EXT4-fs (mmcblk0p1): mounted filesystem with ordered data mode. Opts: (null)

Line 1266:[ 6.205320] Rootfs mounted over mmcblk0p1

…

Line 1298:[ 6.874000] EXT4-fs (mmcblk0p1): re-mounted. Opts: (null)

Line 1299:[ 7.065043] EXT4-fs (nvme0n1p1): warning: maximal mount count reached, running e2fsck is recommended

Line 1583:* /dev/nvme0n1p1 will be checked for errors at next reboot *****

Line 1621:/dev/nvme0n1p1 on / type ext4 (rw,relatime,discard,errors=remount-ro,stripe=8191,data=ordered)

Line 1626:/dev/mmcblk0p1 on /media/jetson/EMMC6 type ext4 (rw,nosuid,nodev,relatime,data=ordered,uhelper=udisks2)

What can I do to prevent the NVME to be mounted as rootfs? Who does that? (I would like to avoid flashing the eMMC, because after booting from the eMMC and repairing the NVME filesystem, I would like to revert to the NVME rootfs.)

Since the card uses U-boot, would booting from an USB drive work?

(I also attach a log of the U-boot environment – using printenv at the U-boot prompt.)

Thank you in advance!
nvidia_developer_forum LOG.txt (108.8 KB)

3

Hi bogdan2435,

Are you using the custom board with Jetson TX2 module?
What’s the Jetpack version in use?

You could refer to the following instruction to change boot order in u-boot.
Flashing and Booting the Target Device - Changing Boot Order with U-Boot

# setenv boot_targets usb0 mmc0 mmc1 nvme0 pxe dhcp
# saveenv
# boot
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Hi Kevin,

Thank you very much for your help.

The board is a Yahboom Jetson TX2 NX Developer kit with Jetpack 4.6 (L4T 32.6.1 Ubuntu 18.04).

I prepared a USB drive with the rootfs and kernel and then booted the TX2-NX with the USB drive in a corresponding USB slot, stopping the booting process at the U-boot prompt.
Unfortunately, it seems that U-boot on the TX2-NX is not capable of recognizing USB devices. The ‘boot’ command produces the following error messages:

489 Tegra186 (P3636-0001) # setenv boot_targets usb0
490 Tegra186 (P3636-0001) # boot
491 maximum number of regions parsed, aborting
492 starting USB…
493 No working controllers found
494 USB is stopped. Please issue ‘usb start’ first.
495 Tegra186 (P3636-0001) # usb start
496 starting USB…
497 No working controllers found

Since USB boot seems impossible on TX2-NX, maybe there might be a way to prevent the unmounting of the eMMC as root and mounting of the NVME as root during the boot process:

[ 6.123422] Root device found: mmcblk0p1
[ 6.168728] Found dev node: /dev/mmcblk0p1
[ 6.193567] EXT4-fs (mmcblk0p1): mounted filesystem with ordered data mode. Opts: (null)
[ 6.205320] Rootfs mounted over mmcblk0p1
…
[ 6.874000] EXT4-fs (mmcblk0p1): re-mounted. Opts: (null)
[ 7.065043] EXT4-fs (nvme0n1p1): warning: maximal mount count reached, running e2fsck is recommended
*** /dev/nvme0n1p1 will be checked for errors at next reboot ***
/dev/nvme0n1p1 on / type ext4 (rw,relatime,discard,errors=remount-ro,stripe=8191,data=ordered)
/dev/mmcblk0p1 on /media/jetson/EMMC6 type ext4 (rw,nosuid,nodev,relatime,data=ordered,uhelper=udisks2)

What can I do to prevent the NVME to be mounted as rootfs? Who does that? Is there maybe a log-file that would give an insight on who is doing the remounting above?

Regarding USB boot, the U-boot menu has also a ‘usb’ command which shows the state of the USB system, but it also fails in the same way:
483 Tegra186 (P3636-0001) # usb start
484 starting USB…
485 No working controllers found

Here is an excerpt of the UART console boot log (the full log is in the attached file):

360 U-Boot 2020.04-g46e4604c78 (Jul 26 2021 - 12:10:58 -0700)
361
362 SoC: tegra186
363 Model: NVIDIA P3636-0001
364 Board: NVIDIA P3636-0001
365 DRAM: 3.8 GiB
366 MMC: sdhci@3400000: 1, sdhci@3460000: 0
367 Loading Environment from MMC… OK
368 In: serial
369 Out: serial
370 Err: serial
371 Net: eth0: ethernet@2490000
372 Hit any key to stop autoboot: 0

373 Tegra186 (P3636-0001) # help
378 boot - boot default, i.e., run ‘bootcmd’
461 usb - USB sub-system

464 Tegra186 (P3636-0001) # usb
465 usb - USB sub-system
466
467 Usage:
468 usb start - start (scan) USB controller
469 usb reset - reset (rescan) USB controller
470 usb stop [f] - stop USB [f]=force stop
471 usb tree - show USB device tree
472 usb info [dev] - show available USB devices
473 usb test [dev] [port] [mode] - set USB 2.0 test mode
474 (specify port 0 to indicate the device’s upstream port)
475 Available modes: J, K, S[E0_NAK], P[acket], F[orce_Enable]
476 usb storage - show details of USB storage devices
477 usb dev [dev] - show or set current USB storage device
478 usb part [dev] - print partition table of one or all USB storage devices
479 usb read addr blk# cnt - read cnt' blocks starting at block blk#’
480 to memory address addr' 481 usb write addr blk# cnt - write cnt’ blocks starting at block blk#' 482 from memory address addr’

483 Tegra186 (P3636-0001) # usb start
484 starting USB…
485 No working controllers found
486 Tegra186 (P3636-0001) # usb reset
487 resetting USB…
488 No working controllers found

489 Tegra186 (P3636-0001) # setenv boot_targets usb0
490 Tegra186 (P3636-0001) # boot
491 maximum number of regions parsed, aborting
492 starting USB…
493 No working controllers found
494 USB is stopped. Please issue ‘usb start’ first.
495 Tegra186 (P3636-0001) # usb start
496 starting USB…
497 No working controllers found

498 Tegra186 (P3636-0001) # printenv
…
515 boot_targets=usb0
526 bootcmd_usb0=devnum=0; run usb_boot
…
601 Tegra186 (P3636-0001) # run bootcmd_usb0
602 starting USB…
603 No working controllers found
604 USB is stopped. Please issue ‘usb start’ first.

Thanks again!
usb boot not working NUMBERED.txt (34.9 KB)

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This is the custom board from Yahboom.

Please also and other boot device in order.

Your serial console log has already showed this information.
[ 6.123422] Root device found: mmcblk0p1

Do you format your USB drive as boot device before use it?

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