Where are the boot configuration files?

Where can I find boot configuration files?

I recorded JP 4.2.3 to SD card using Etcher. There are several partitions on this SD card - the main partition is in EXT format, other partitions in Windows and Ubuntu do not open. For example, SD card with Raspbian OS has a FAT partition with configuration files.

I also do not have the following folders, which are mentioned in the Tegra Linux Driver Package Development Guide:

linux_for_tegra/
bootloader/

Thanks for answers!

hello lich.mk,

according to Getting Started With Jetson Nano Developer Kit,
may I know how did you install the OS release, did you using SDKManager?
thanks

I used Etcher to write Developer Kit image to SD card. I did not use the SDK Manager because I am working in Windows.

hello lich.mk,

Etcher tool only create partitions and write the OS image into SD-card,
if install the OS image with SDKmanager, your local host machine would also generate below two folders.
for example,
~/nvidia/nvidia_sdk/JetPack_4.2.2_Linux_GA_P3448/Linux_for_Tegra/
~/nvidia/nvidia_sdk/JetPack_4.2.2_Linux_GA_P3448/Linux_for_Tegra/bootloader/

were you looking for boot configuration table (BCT)?
could you please share some details of your use-case.
thanks

Hello JerryChang,

Thank you for the quick answer!

Do I understand correctly that I cannot access the bootloader / and hardware / partitions without using SDKmanager?

What I want to do:

  1. View and change the list of devices that are polled by the system at boot. During the boot process, an errors notification appears: imx219, iwlwifi, hdmi, thermal_zone and others. After loading, the system works fine, incl. display and wifi module.
  2. Set display parameters manually. It seems that the system automatically determines the screen resolution at boot and restarts (the size of the Nvidia logo is changed during the boot process). This increases startup time.

I guess I need to create a separate topic about these errors and attach screenshots.

In theory you could do it without SDKmanager if you wrote your own replacement, however realistically, SDKmanager is required. It can run fine from within a VM if you don’t care about flashing devices directly.

You can modify the device tree from within the Linux_for_Tegra folder. Here is a thread on that:

https://devtalk.nvidia.com/default/topic/1051983/jetson-nano/howto-update-dtb-on-jetson-nano/

… however it probably won’t get you much in terms of boot time. What will is disabling services. You can do this using the “systemctl” command with the “–root” option pointed to wherever your rootfs is (under Linux_for_Tegra) and create-jetson-nano-sd-card-image.sh (also in Linux_for_Tegra) can be used to create a bootable SD image after such modifications are made.

for example

sudo systemctl --root=/path/to/rootfs list-unit-files

would list the unit files (services) on your rootfs. You can then enable or disable them as desired, even adding your own services if you want.

The command works exactly the same as on a Debian based OS like Ubuntu, only with --root you specify that you’re operating on a rootfs folder is rather than /

Please do make sure to remember the --root option, otherwise you will operate on your host system (or vm) which is probably not what you want.

You can, of course, run systemctl directly on a booted nano to enable/disable services. The modifications to the rootfs folder are only necessary if you wish to master your own image.

Here is a thread for that, but again, I’m not sure if it’ll save you much time.
https://devtalk.nvidia.com/default/topic/1043732/jetson-tx2/change-the-default-output-resolution-from-720p-to-1024-1280/