Orin Nano UEFI selection of the kernel image and the DTB

[matt.read]

Im on the Orin Nano JP 6.0.0 with AB booting enabled. Does any one know what would happen if the DTB in the QSPI failed to load for both A/B slots in the section “Use the UEFI DTB”. I am looking at following flowchart from:
https://docs.nvidia.com/jetson/archives/r36.3/DeveloperGuide/SD/Bootloader/UEFI.html#dtb-support

If QSPI failed to load the DTB for both A/B slots would it panic or would it go into bootloader recovery mode as it would mark both slots A and B as invalid:

My second question: If the path below is followed in slot A would it attempt to changed to Slot B and boot before it tried to load the recovery kernel?

[KevinFFF]

Hi matt.read,

@matt.read

If QSPI failed to load the DTB for both A/B slots would it panic or would it go into bootloader recovery mode as it would mark both slots A and B as invalid

If it can not boot up successfully due to DTB, then it would trigger reset. After 3 times trails, it will switch to another slot. If it still can not boot up successfully from that slot for 3 times, then it will enter into recovery kernel state.

@matt.read

My second question: If the path below is followed in slot A would it attempt to changed to Slot B and boot before it tried to load the recovery kernel?

Yes, as the full flow I stated above.

[matt.read]

Hi KevinFFF thanks for you help,

just to be clear then if slot A and B can not boot up successfully after 3 times trails due to DTB it will enter into recovery kernel state and not the bootloader recovery mode (UEFI shell)?

I just want to clarify this as it goes against the information I got from the post: A/B system conflicting information

I should have mentioned it earlier but I am on JetPack 6.0.0 (rev 2) L4T r36.3.0,
Linux 5.15.136-tegra, Ubuntu 22.04.4 LTS.

As I’m on L4T-r36.3.0 would it enter the bootloader recovery mode (UEFI shell) on DTB failure and not the recovery kernel state as this changed since L4T-r35.2?

[KevinFFF]

@matt.read

just to be clear then if slot A and B can not boot up successfully after 3 times trails due to DTB it will enter into recovery kernel state and not the bootloader recovery mode (UEFI shell)?

Correct! The UEFI shell will be entered only when the boot-devices can’t be loaded.

@matt.read

I just want to clarify this as it goes against the information I got from the post: A/B system conflicting information

The A/B slots for bootloader is enabled by default.
If you enable rootfs redundancy, then it will tie to A/B bootloader as that thread mentioned.