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bootloaderbootu-bootnvidia-jetson

NVIDIA Jetson TX2

I want to buy the Jetson Tx2 in order to do some deep dive. According to their Docs, the Bootloader at some point executes the C-Boot followed by U-Boot. C-Boot runs with Exception Level (EL) 2, does somebody know whether C-Boot passes EL 2 to U-Boot (or C-Boost passes EL 3 to U-Boot)?

If you have a Tx2 you could simply test it by:

dmesg | grep EL

Thanks in advance!

Solution

  • TF-A drops to EL2 before invoking Cboot. See https://docs.nvidia.com/jetson/archives/l4t-archived/l4t-3231/index.html#page/Tegra%2520Linux%2520Driver%2520Package%2520Development%2520Guide%2Fbootflow_tx2.html%23. U-Boot then also runs at EL2. If you want to run software in the secure zone, you could use OP-TEE.

    Should U-Boot be called in EL3 and you boot via UEFI U-Boot will drop to EL2 before loading the EFI binary by calling the function switch_to_non_secure_mode().