[TF-M] Combine secure and non-secure image

Hi all,

I abandoned the idea to build at once tf-m and zephyr and switched to separated compilations.

Now, I have both secure and non-secure binaries but I’m not sure how to concatenate and sign them.

I found the assemble.py script but I don’t know whether it is the correct one or where to find the signing_layout.

To be more specific, for my current target musca-a (going to switch to musca-s as soon as it arrives): I built TF-M I imported and included in my zephyr application both libpsa_api_ns.a and libtfm_s_veneers.a I build my zephyr application Now (I suppose) I have to merge zephyr.bin with tfm_s.bin sign the merged binary concatenate with bl2 I could not find any reference how to correctly do these last steps.

Best,