MCUBoot+sysbuild+ns-variant: E: Protect mcuboot flash failed, cancel startup.

[Erlend Isachsen]

Hi.

Goal
I am creating a new application for the nRF54l15 and want to follow the latest recommendations for project configuration. I need to do DFU over BLE, so I'm trying to add MCUBoot in the chain-of-trust regime, using sysbuild. To get there, I used the zephyr/samples/sysbuild/with_mcuboot as a starting point.

Problem
The sample in question does not explicitly support any of the nordic boards with secure/non-secure regime, and I haven't found any samples that combine all these criteria. So I have tried to build the zephyr/sysbuild/with_mcuboot sample for nrf54l15dk/nrf54l15/ns. After erase+flash to my nRF54l15-PDK, I get the following error:

*** Booting MCUboot v2.1.0-dev-2b69d93e75bc ***
*** Using nRF Connect SDK v3.1.0-6c6e5b32496e ***
*** Using Zephyr OS v4.1.99-1612683d4010 ***
E: Protect mcuboot flash failed, cancel startup.

How to recreate
Open zephyr/sysbuild/with_mcuboot and build for zephyr/sysbuild/with_mcuboot sample for nrf54l15dk/nrf54l15/ns. My first build failed, but after doing a pristine build it built successfully and I was able to flash (VSCode build output is attached). Finally, flash to the DK and it should produce the error message shown above.

My setup
Support information is attached. I'm using SDK and toolchain version 3.1.0 with VSCode for windows 10, and nRF54L15-PDK (0.8.1, 2024.38).

Solutions?
I don't have to be able to run this exact sample, but what is causing this error and how do I best resolve it?

vscode_build_log.txt 

Fullscreen nrf-connect-support-20250818091511.json Download

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// If you do not want others to see this information, make sure to remove it before sharing the data.

// For help and support, visit Nordic Semiconductor's DevZone at https://devzone.nordicsemi.com/.

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[Erlend Isachsen]

Thank you for the update, and thanks for reporting it internally.

I believe the build would probably succeed using the non-ns variant of the board, and I believe it would also work by disabling FPROTECT. However, this is a very big compromise considering it might make it challenging to get our product certified with regards to the upcoming IoT security regulations such as CRA, where DFU/FOTA will be a requirement and most points under CRA Annex 1 relates to the configurations discussed in this thread. It would also be surprising if such a compromise is required, considering security is one of the selling points of the nRF54 series is:

"
Advanced security features with physical protection
With more IoT security regulations, customers increasingly recognize the value of security. The nRF54L Series enables secure products, integrating features such as secure boot, secure firmware update, secure storage, a trusted execution environment enabled by TrustZone, and a cryptographic accelerator. These features, alongside side-channel leakage protection and tamper detectors, fulfill essential and rigorous security requirements.
"

Also, I imagine there are very few instances where you would want to use TFM without FPROTECT? I might be missing something, but wouldn't TFMs security be compromised by the fact that the application can simply modify the TMF? As far as I can tell they go hand in hand.

So to assist customers planning to use the nRF54 for its secure features, or customers that want to be compliant with existing and future cybersecurity regulations and care about certification, it would be very helpful to have a sample in the nRF Connect SDK that has security enabled by default (possibly two samples, one central device and one peripheral?). As a minimum for compliance with the most central IoT security regulations, it should probably include the following:

1. Builds for the _ns variant of the nRF54 development kits with TFM.
  a. to be compliant with most points under CRA Annex 1.
2. Has secure bluetooth with recommended DFU services enabled.
 a. Assuming most customers choosing the 54 series are interesting in using bluetooth.
 b. DFU to be compliant with CRA requirements related to security updates and lifecycle support.
3. Uses the key provisioning and KMU for the benefits you mentioned.

Or whichever configuration you see fit to actually "fulfill essential and rigorous security requirements." and be compliant with "IoT security regulations", because that is essentially what I'm trying to achieve. This also ties into the "secure by default configuration" listed under CRA Annex 1.

I'm referring a lot to CRA considering it is one of the big upcoming IoT security regulations, and it will be become part of the CE requirements in 2027.

[Menon]

Hello,

I understand your concern, and I completely agree that this needs to be fixed. I am closely following the issue and will update you as soon as it is resolved. I’m sorry for the delay and apologize for the inconvenience this has caused.

Kind regards,
Abhijith

[Yannick Bus]

Hello,

We are having the same issue as the gentleman above, enabling FProtect for us seems to result in "<err> mcuboot: Protect mcuboot flash failed, cancel startup." However we are allready on a non-ns build.

Have there been any updates or workarounds for this issue found in the meantime?

Kind Regards,
Yannick Bus

[Erlend Isachsen]

Hi. Maybe I can provide some help. If FProtect fails it is likely that your MCUBoot primary partition has a too big offset from the start of the flash. On ns-builds, this will typically be caused by TFM partitions as discussed above. Since you are on a non-ns build, it means something else is taking up that space. For instance, I wouldn't be surprised if this happens when using MCUBoot as a second stage bootloader.

If you don't need flash protection you can use CONFIG_FPROTECT=n (in sysbuild/mcuboot.conf) to disable it as mentioned, although I would not recommend this as it increases the chance of bugs related to flash-writes (FOTA etc.) to brick your device.

If you need flash protection it would be useful if you can share your pm_static.yml if you have one, or build/partitions.yml. In the latter file, you can check which partitions are before mcuboot_primary. mcuboot_primary address needs to be before 0x10000 on nRF54L15.

If I'm not mistaken, I believe MCUBoot simply looks for the begining of mcuboot_primary, and tries to protect everything before it (including mcuboot itself), and the maximum fprotect size is 64 kiB (0x10000).

[Yannick Bus]

Hello,

Our pm_static.yml has only a single entry:

mcuboot:
  address: 0x00000000
  size:    0x00018000

as far as i can see from the generated partitions.yml there isnt anything too crazy:

mcuboot:
  address: 0x0
  end_address: 0x18000
  region: flash_primary
  size: 0x18000
mcuboot_pad:
  address: 0x18000
  end_address: 0x18800
  placement:
    align:
      start: 0x1000
    before:
    - mcuboot_primary_app
  region: flash_primary
  size: 0x800
mcuboot_primary:
  address: 0x18000
  end_address: 0x165000
  orig_span: &id001
  - mcuboot_pad
  - app
  region: flash_primary
  size: 0x14d000
  span: *id001
mcuboot_primary_app:
  address: 0x18800
  end_address: 0x165000
  orig_span: &id002
  - app
  region: flash_primary
  size: 0x14c800
  span: *id002
mcuboot_secondary:
  address: 0x0
  device: DT_CHOSEN(nordic_pm_ext_flash)
  end_address: 0x14d000
  placement:
    align:
      start: 0x4
  region: external_flash
  share_size:
  - mcuboot_primary
  size: 0x14d000

The only thing i can think of is that we are using an external flash chip for the mcuboot_secondary?

Thank you for your reply!