Clarification on the NXP SBL Project

ofirmsh — Mon, 11 Mar 2024 15:57:48 GMT

Hello,
I am using iMX RT1170, and trying to insert a secondary bootloader into our application. I ran into a couple of questions that I would like to be clarified before continuing on. And yes, I read the SBL Application Note and User Guide.

The SBL Project GitHub repository mentions that "This project is not under active development now. For actively maintained examples of second stage bootloader based on MCUBoot see the latest release of MCUXPresso SDK".

1. As I gathered, the purpose of the SBL project is to generate the second-stage bootloader code per board, based on user configuration (swap/remap modes, execution addresses, etc). Is this correct?

2. The last meaningful commit on the SBL project was in 2021.

Is it due to actual lack of needed updates?
Did the SBL repo become part of the SDK and is thus no longer relevant?
Did only the examples move to be part of the SDK but the SBL project itself is still useable?

3. The latest MCUX SDK examples seem to be pre-generated SBL code per board. Is this really what is happening? Is it safe to fork the SBL repository, configure it via menuconfig to RT1176 and expect the same behavior as the examples?

4. The user guide mentions a few tools to aid in firmware updates, notably:

MCUBoot's imgtool
NXP Secure Provisioning Tool
NXP MCUBootUtility
blhost

MCUBootUtility and Secure Provisioning Tool seem to serve the same purpose. Both use blhost. Both sign an image (though it does not seem like they do that with imgtool). Does it matter which one I sign and flash my binary with? Which one of these suit the format dictated by SBL? Ideally we want this process to be automated with a script.

Thank you!

Re: Clarification on the NXP SBL Project

diego_charles — Thu, 11 Apr 2024 22:04:27 GMT

Hi @ofirmsh

Thank you very much for your patience.

1 Yes, your understanding is correct.

2 The former development team still have not met the need to update this reference design. The SBL reference design is still usable.

3 The SBL is not integrated within the SDK, therefore the SDK examples are not pre-made to work with the SBL.

4 The MCUBoot Utility and the Secure Provisioning Tool can be used to sign and flash on the same way, but you are correct, these tools do not integrate the imgtool. Therefore, they will not work when the SBL requires you to enable secure boot or encrypted boot with the imgtool.

I hope this could help you.

Diego

MCUXpresso GeneralのトピックClarification on the NXP SBL Project

Clarification on the NXP SBL Project

Re: Clarification on the NXP SBL Project