When FDT is not specified in extlinux.conf, where does the dtb come from?

Robotics & Edge Computing Jetson Systems Jetson Nano
1

I see this is on the SD card:

     Device: /dev/mmcblk0p10
      Start: 18432
        End: 19327
    Sectors: 896
       Size: 448K
       Type: Linux filesystem
  Type-UUID: 0FC63DAF-8483-4772-8E79-3D69D8477DE4
       UUID: 9F7DF322-ACE3-4203-967A-B515F102B06D
       Name: DTB

It’s not a file system that can be mounted, and it’s not a dtb file that dtc recognizes.

How can I peek inside?

1 Like
2

Hi tunretni,

This dtb is from the DTB partition.

https://docs.nvidia.com/jetson/l4t/index.html#page/Tegra%2520Linux%2520Driver%2520Package%2520Development%2520Guide%2Fpart_config.html

3

Hello tunretni,

Also, the dtb that’s loaded can be found at /sys/firmware/devicetree/base which can be extracted to a .dts file using the below command:

dtc -I fs -O dts -o $HOME/extracteddtb.dts /sys/firmware/devicetree/base

The “dtc” command is installed through the package “device-tree-compiler”

4

You can also view the device tree via /proc/device-tree. The dtc tool can generate dts from the filesystem. I often do that to be certain of what really is being used.