nRF53 network core bootloader fails to start because ACL full

[Stephan Walter]

We are using nRF5340 engineering D revision.

The software is nRF Connect SDK 1.7.0

We are seeing a problem with the network core bootloader (aka netboot, aka b0n)

Sometimes the bootloader fails to start the network core application.

We have enabled logging in the bootloader, then we see the following error message:

Failed to protect b0n flash, cancel startup

Looking into nrf\samples\nrf5340\netboot\src\main.c, we see that the bootloader tries to lock the flash using the ACL peripheral.

This fails because apparently the ACL list is not cleared on reboot. The function find_free_region then returns an error.

We reboot the chip using the shell command kernel reboot cold on the application core, which should also reset the network core according to the specification.

Is this a known hardware issue, or are we doing something wrong in software?

[Simon]

This is an issue I have not seen before and not familiar with. Would you be able to provide a detailed description how to reproduce it (upload a simplified sample if necessary)?

[Stephan Walter]

Hi Simon,

I got an email notification but I'm not seeing your reply here. You say that you can't reproduce the issue with nRF5340 DK v0.11.0. We agree on that.

The problem does occur with a chip that has a different INFO.CONFIGID in FICR. Does that mean that there are differences in the dies, despite both being revision D?

[Simon]

I deleted the reply, because I read your replies too fast, and gave a nonsensical answer, but yes, I was not able to reproduce it using an nRF5340 DK.

I'm not sure why you're seeing the different behavior between the chips. I have forwarded this internally, and will keep you updated if I get any inputs.