mcuboot: nordic development kits fail to compile

[JordanYates]

Describe the bug

The following Nordic development kits fail to compile the upstream mcuboot application.

• nrf9161dk@0.7.0/nrf9161
• thingy52/nrf52832
• thingy53/nrf5340/cpuapp

Enabling multithreading by removing the following line lets them all compile:
https://github.com/zephyrproject-rtos/mcuboot/blob/d4394c2f9b76e0a7b758441cea3a8ceb896f66c8/boot/zephyr/Kconfig#L751

To Reproduce

west build -b nrf9161dk@0.7.0/nrf9161 bootloader/mcuboot/boot/zephyr/ -p
west build -b thingy52/nrf52832 bootloader/mcuboot/boot/zephyr/ -p
west build -b thingy53/nrf5340/cpuapp bootloader/mcuboot/boot/zephyr/ -p

Expected behavior

Development kits should successfully compile the standard Zephyr bootloader

Environment (please complete the following information):

• Zephyr v3.6.99 ea29ef3

[nashif]

why is this a zephyr bug? Please report at nordic NCS.

[JordanYates]

why is this a zephyr bug? Please report at nordic NCS.

Why is this a NCS bug? It's a Zephyr bug because these are Zephyr supported platforms failing to compile the Zephyr bootloader.

[nordicjm]

Fix: mcu-tools/mcuboot#1984

[JordanYates]

I am now discovering the situation is worse for me with the fix than it was without it :)
Before I could simply set mcuboot_CONFIG_MULTITHREADING=y in my sysbuild config and everything would be fine.
Now I have no board agnostic way to enable the external flash drivers in MCUboot...

[nordicjm]

I am now discovering the situation is worse for me with the fix than it was without it :) Before I could simply set mcuboot_CONFIG_MULTITHREADING=y in my sysbuild config and everything would be fine. Now I have no board agnostic way to enable the external flash drivers in MCUboot...

it needs to be done on a board by board basis, if you want to do that then I would suggest using sysbuild with your application and having a sysbuild/mcuboot folder with your MCUboot files, you can then create a boards folder there and have your overlays for each board, or alternatively setting mcuboot_APPLICATION_CONFIG_DIR to a common place if you need it across multiple repos/applications.

Example: https://github.com/nrfconnect/sdk-nrf/tree/main/applications/machine_learning

[JordanYates]

That's just not a scalable solution. Copy pasting files into every application is a poor solution when better solutions exist IMO.
Happy to continue the conversation on this PR and why you think its a bad idea :)
mcu-tools/mcuboot#2015