MCUboot external signing script - SIGNING_SCRIPT Variable Bug in nRF

[martin_k]

Hi All,

I am currently working on an project with the nRF9151 using the nRF SDK v3.1.1 and MCUboot and I need to sign my application images using an external HSM.
I am using sysbuild and set -Dapplication_SIGNING_SCRIPT (my image is called application) as defined by https://docs.nordicsemi.com/bundle/ncs-3.1.1/page/zephyr/build/signing/index.html#extending_signing_externally.
My script was never called and after some testing I found out, that in "sysbuild/CMakeLists.txt" the variable is always overwritten to the default without checking if a custom signing script is selected. See CMakeLists.txt on Github. Is this the expected behavior or is there a workaround or different solution? I do not like to modify the nRF SDK directly.

If this is the problem it may also help to solve RE: Signing script not working as expected and RE: Application with MCUBoot and external signature.

Best regards,
Martin

[louispalmer10]

I ran into the same issue and worked around it by overriding SIGNING_SCRIPT in my own CMake layer after sysbuild runs, which forces the custom script to be used without modifying the SDK directly. basketball stars

[martin_k]

That sounds like a nice workaround and I will try this. Do you have by any chance the code snipped of your cmake for overwriting the SIGNING_SCRIPT. Would be great, because I am not so to used to cmake and it will help me a lot.

Thank you, Martin