Hi. I was looking into a failing test-case in the Zephyr project for the NMI not being processed when using TF-M.

The issue is that SCB.AIRCR.BFHFNMINS bit is not set, so the non-secure write to SCB.ICSR.NMIPENDSET is ignored.

Is this a decision that was explicitly made for the TF-M configuration to not allow the non-secure application to use the NMI handler?

I could not find anything in the TF-M documentation mentioning the NMI.

Are there security concerns related to the NMI?

Joakim Andersson | Senior R&D Engineer
Trondheim, Norway