Hi Fabian,

On Thu, 5 Dec 2024 at 06:09, Koch, Fabian Fabian.Koch@hima.com wrote:

Hey all,

I have a SoC which does secure boot in a multi staged process. (ROM loads a signed SPL to an aux core, which loads another signed SPL to main core, which loads a signed u-boot.img)

But the thing I want u-boot to load, verify signature and then run/boot is a standalone binary app, not a Linux Kernel. (It does work fine when I load that and run it with the "go" command, but no signature verification is done as of now)

All the research I did pointed towards using signed FIT images and then "bootm" to do the verification and loading. But I cannot get "bootm" to load a FIT containing only my raw binary standalone app.

Is that road a dead-end and I need to do something completely else?

I would love to stay as close to vanilla u-boot (or at least the SDK vanilla version) and not implement a fully custom signature verification.

Any pointers would be highly appreciated.

So long as you put your image in a configuration, it can be verified. The question is whether you can load it.

bootm assumes it is booting an OS. It does not support IH_TYPE_FIRMWARE as a type. You could write a new command to handle that, perhaps. SPL does support loading firmware, but you are running U-Boot proper so that isn't very useful.

For your command, you could call fit_config_verify() to verify the config, then fit_image_load() to load the image you want.

Regards, Simon

kind regards Fabian

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