Nrf desktop hid mcuboot development

RE: Nrf desktop hid mcuboot development

SwRa — Fri, 26 Jun 2026 13:29:20 GMT

Hi Jiale,

It is a known issue. FPROTECT can support locking up to 62 KB of RRAM on nRF54L SoCs when used by immutable MCUboot. Either the partition declared for MCUboot or its size might be too large for using FPROTECT. Your MCUboot partition is 64 KB (0x10000), which exceeds the supported limit. The RRAMC hardware on nRF54L only provides two regions (3 and 4) for protection:

Up to 31 KB → uses RRAMC region 4 alone
Between 31 KB and 62 KB → uses both regions 3 and 4 (requires CONFIG_FPROTECT_ALLOW_COMBINED_REGIONS)
Above 62 KB → not supported, causes a static assertion failure

Refer: https://nrfconnectdocs.nordicsemi.com/ncs/latest/nrf/app_dev/device_guides/nrf54l/dfu_config.html#nvm-protections

You will either need to decrease the partition size to less than 62 KB or Disable FPROTECT as you did. You can disable it by setting CONFIG_FPROTECT=n in your MCUboot configuration, but this removes write protection from the bootloader region, which is a security risk in production firmware.

Best Regards,

Swathy

RE: Nrf desktop hid mcuboot development

CJL — Tue, 19 May 2026 04:09:18 GMT

I have already adjusted the alignment to 4KB, but this may not be the root cause. I commented out the code below and it can run. What is the problem?

D:\ncs\v3.1.1\nrf\lib\fprotect\fprotect_rram.c

int fprotect_area(uint32_t start, size_t size)

RE: Nrf desktop hid mcuboot development

SwRa — Mon, 18 May 2026 12:10:54 GMT

Hi Jiale,

It is essential that your slot partitions for mcuboot (primary, secondary) are both aligned at their start address on a flash erase sector boundary AND that their size is ALSO aligned on an erase boundary. Please refer the discussion in the following thread: DFU using USB file system (not serial emulation)? Your mcuboot_primary_size of 0xb4800 is also not 4KB-aligned. please try fixing it.

Best Regards,

Swathy

RE: Nrf desktop hid mcuboot development

CJL — Thu, 14 May 2026 00:53:16 GMT

ncs sdk version:3.1.1