Watchdog isn't being fed during MCUboot image confirmation - loop reboot

RE: Watchdog isn't being fed during MCUboot image confirmation - loop reboot

Menon — Tue, 08 Jul 2025 17:54:18 GMT

Hello,

I'm not sure where this undefined reference is coming from. Could you please share the full build logs here? Also, enable debug-level logging, this might help identify the exact origin of the errors.

Kind regards,
Abhijith

RE: Watchdog isn't being fed during MCUboot image confirmation - loop reboot

jolive — Fri, 04 Jul 2025 16:39:44 GMT

Hi,
Initially, I was using NCS version 2.9.1, and builds without problems.

After upgrading to NCS 3.0.1, I started encountering the following linker errors:

undefined reference to `z_impl_k_sem_give'
undefined reference to `z_impl_k_sem_take'

This issue also occurs in the sample:
zephyr/samples/sysbuild/with_mcuboot

I added an app.overlay file with the following content:

/ {
aliases {
watchdog0 = &wdt30;
};
};
&wdt30 { status = "okay"; };

This configuration builds without any issues in NCS 2.9.1. However, in NCS 3.0.1 I have the same errors mentioned above.

RE: Watchdog isn't being fed during MCUboot image confirmation - loop reboot

Menon — Tue, 01 Jul 2025 11:16:42 GMT

Hello,

Which SDK version are you using here?

Kind Regards,

Abhijith

RE: Watchdog isn't being fed during MCUboot image confirmation - loop reboot

Turbo J — Fri, 27 Jun 2025 17:21:01 GMT

No, MCUBoot won't feet the WDT by default.

RE: Watchdog isn't being fed during MCUboot image confirmation - loop reboot

jolive — Fri, 27 Jun 2025 15:19:10 GMT

Hello,

As I understand it, MCUboot is supposed to feed the watchdog during the OTA update process, right?

In my case, if I increase the watchdog’s timeout window to 2000 ms, the update completes successfully without any issues. However, with a 1000 ms window - which is the maximum acceptable value for my application - the system resets, suggesting that MCUboot isn’t feeding the watchdog as expected.

RE: Watchdog isn't being fed during MCUboot image confirmation - loop reboot

jolive — Fri, 27 Jun 2025 14:43:14 GMT

Hello,

I added the following configurations to my mcuboot.conf:

CONFIG_BOOT_WATCHDOG_FEED=y

CONFIG_WATCHDOG=y

CONFIG_WDT_NRFX=y

CONFIG_NRFX_WDT30=y

I also added this alias in my device tree overlay:

aliases {
watchdog0 = &wdt30;
};

However, the issue still persists — the watchdog is not being fed during MCUboot

RE: Watchdog isn't being fed during MCUboot image confirmation - loop reboot

Menon — Fri, 27 Jun 2025 13:45:55 GMT

Hello,

When the device restarts after a firmware update, MCUboot, runs first. At this point, the main application hasn't started yet, so the watchdog isn't being fed. If the time taken by MCUboot and the system startup exceeds the watchdog timeout of 1000 ms, the watchdog assumes something has gone wrong and resets the system. This reset brings the device back to the beginning of the boot process, causing it to loop continuously without ever fully starting the application.
So what happens when you give the watchdog more time (>1000ms), the system has enough time to finish booting and start the app, which feeds the watchdog. No more resets.

Kind Regards,

Abhijith

RE: Watchdog isn't being fed during MCUboot image confirmation - loop reboot

Turbo J — Thu, 26 Jun 2025 08:15:08 GMT

MCUboot does not know about the watchdog. Read the sysbuild chapters in the documentation.

I believe you can influence the device tree (via overlay) and the project config enough to include watchdog support when MCUboot runs.