Adding device tree overlay to extlinux.conf

Robotics & Edge Computing Jetson & Embedded Systems Jetson Xavier NX
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1

Hi,
I use Jetson Xavier NX with below OS spec :

$ cat /etc/nv_tegra_release 
# R35 (release), REVISION: 5.0, GCID: 35550185, BOARD: t186ref, EABI: aarch64, DATE: Tue Feb 20 04:46:31 UTC 2024

$ cat /etc/os-release 
NAME="Ubuntu"
VERSION="20.04.6 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.6 LTS"
VERSION_ID="20.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal

I want add device tree overlay by editing /boot/extlinux/extlinux.conf file as below :

$ cat /boot/extlinux/extlinux.conf
TIMEOUT 30
DEFAULT primary

MENU TITLE L4T boot options

LABEL primary
      MENU LABEL primary kernel
      LINUX /boot/Image
      FDT /boot/dtb/kernel_tegra194-p3668-0001-p3509-0000.dtb
      FDT_OVERLAY /boot/tegra194-p3668-all-p3509-0000-adafruit-sph0645lm4h.dtbo
      INITRD /boot/initrd
      APPEND ${cbootargs} root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4 console=ttyTCU0,115200n8 console=tty0 fbcon=map:0 net.ifnames=0 video=efifb:off nospectre_bhb

# When testing a custom kernel, it is recommended that you create a backup of
# the original kernel and add a new entry to this file so that the device can
# fallback to the original kernel. To do this:
#
# 1, Make a backup of the original kernel
#      sudo cp /boot/Image /boot/Image.backup
#
# 2, Copy your custom kernel into /boot/Image
#
# 3, Uncomment below menu setting lines for the original kernel
#
# 4, Reboot

# LABEL backup
#    MENU LABEL backup kernel
#    LINUX /boot/Image.backup
#    FDT /boot/dtb/kernel_tegra194-p3668-0001-p3509-0000.dtb
#    INITRD /boot/initrd
#    APPEND ${cbootargs}

The device tree file is presented and permission set to 644 :

$ ls -lh /boot/tegra194-p3668-all-p3509-0000-adafruit-sph0645lm4h.dtbo
-rw-r--r-- 1 root root 1.1K Feb 20  2024 /boot/tegra194-p3668-all-p3509-0000-adafruit-sph0645lm4h.dtbo

but after reboot I get this Error in booting time :

Jetson UEFI firmware (version 202210.4-d00a5d3a-dirty built on 2024-10-16T05:00:
52+03:30)

** WARNING: Test Key is used. **

L4TLauncher: Attempting Direct Boot
OpenAndReadUntrustedFileToBuffer: Failed to open _OVERLAY \boot\tegra194-p3668-a
11-p3509-0000-adafruit-sph06451m4h.dtbo: Not Found
ExtLinuxBoot:sds Failed to Authenticate boot\extlinux\extlinux.conf (Not Found)
LATLauncher: Unable to boot via extlinux: Not Found
LATLauncher: Attempting Kernel Boot
EFI stub: Booting Linux Kernel...
EFI stub: Using DTB from configuration table
EFI stub: Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path
EFI stub: Exiting boot services and installing virtual address map...

Why dose this error occur and bootloader is unable to find device tree file?
How to solve it?

Thanks.

3

Hi, try FDTOVERLAYS instead of FDT_OVERLAY. You can also check this page https://docs.nvidia.com/jetson/archives/l4t-archived/l4t-3275/index.html#page/Tegra%20Linux%20Driver%20Package%20Development%20Guide/uboot_guide.html#wwpID0E0YD0HA.

4

Hi 1408,
Thanks to replay to me.
My nv_tegra_release is : 35.5.0 and boot loader is UEFI.
But your link is for older version, and about u-boot not UEFI.

5

I’m no expert in bootloaders, but if you use extlinux, the procedure should be the same. I made it work for 35.5.0 in the same way (it was on a AGX Xavier, though).
Did you give it a try by replacing FDT_OVERLAY with FDTOVERLAYS in the extlinux.conf file?

6

boot parameters in the extlinux.conf file depended to the boot loader, and boot loader must be supported it.
yes i was try FDTOVERLAYS. but boot loader only response to FDT_OVERLAY by error message.

7

FDT_OVERLAY is not supported in rel-35 bootloader.

9

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