Hi all,

due to how advanced security features (TEE) and device firmware
upgrade (MCUBoot) is organized we are seeing the need to boot
Zephyr applications in multiple stages. A real-world use-case of
even a 3-stage boot process has been identified and tested at
Nordic.

Each bootloader needs to be individually upgrade-able and have
it's own configurations of Zephyr libraries. To achieve this each
bootloader must be organized as it's own executable.

To make matters worse, in a multi-core AMP system each core would
also require at least one executable.

The problem is that the build system can only build one
executable. This creates a usability issue as the user must
invoke a large set of arcane commands to build, sign, and flash
each executable.

After considering many options we have finally ended up with a
solution proposal that is merge-ready. See the PR for details

https://github.com/zephyrproject-rtos/zephyr/pull/13672

Please add your feedback in the PR and let us know what you think
of the proposed change.

SEBASTIAN BØE | Software Developer
Trondheim, Norway
nordicsemi.com | devzone.nordicsemi.com