LittleFS and settings subsystem

RE: LittleFS and settings subsystem

Elfving — Wed, 07 Jan 2026 09:18:21 GMT

Great! Glad to hear it Jan, and thanks for sharing the solution 🙂

Let us know if there is anything else!

Regards,

Elfving

RE: LittleFS and settings subsystem

janR — Mon, 05 Jan 2026 14:17:06 GMT

Hello Elfving,

No worries regarding to time to answer. I have been on vacation since before Christmas.

I managed to find the cause myself. In case someone have similar problem, here are the changes I had to do:

In the pm_static file:

settings_storage:
  address: 0x003fe000
  end_address: 0x00400000
  size: 0x00002000
  region: external_flash
  device: mx25r6435f
littlefs_storage:
  address: 0x00000000
  end_address: 0x003fe000
  region: external_flash
  device: mx25r6435f
  size: 0x003fe000
  affiliation: disk
  extra_params: {
      disk_name: "littlefs",
      disk_cache_size: 4096,
      disk_sector_size: 512,
      disk_read_only: 0
    }

In the Littlefs setup (.h file):

fs_mount_t m_littlefs_mnt = {
        .type = FS_LITTLEFS,
        .mnt_point = "/lfs",
        .fs_data = &m_littlefs_data,
        .storage_dev = (void*)FIXED_PARTITION_ID(littlefs_storage),
    };

In the cpp file:

int res = fs_mount(&m_littlefs_mnt);

.storage_dev was set wrong (to this)

.storage_dev = (void*)FIXED_PARTITION_ID(storage_partition)

In addition I have this in an overlay file:

/ {
    chosen {
        nordic,pm-ext-flash = &mx25r64;
    };
};

With these changes Settings and Littlefs uses the mx25 with its own partitions.
And everything works.

RE: LittleFS and settings subsystem

Elfving — Fri, 19 Dec 2025 14:16:15 GMT

Hi again Jan,

Sorry but I haven't had too much time to look into this, though there seem to be some documentation here on how to set up external partitions. Could you have a look at that, and try using nordic,pm-ext-flash = &mx25r64? I didn't get the impression that this is how you are currently handling it. It did end up helping in a previous DZ case.

Could you also show me the configurations you have enabled, and how resulting dts ends up looking in the two scenarios? I am eg. wondering if CONFIG_PM_PARTITION_REGION_LITTLEFS_EXTERNAL has been set either explicitly or implicitly.

[quote user=""]settings_storage" partition in the pm file[/quote]

Just to confirm, this is a pm_static file, correct?

For more than this though, I have to get back to you after new years, I hope that is fine.

Regards and happy holidays,

Elfving

RE: LittleFS and settings subsystem

Elfving — Mon, 15 Dec 2025 14:41:42 GMT

Hei Jan,

I'll have to get back to you on this later this week. Hope thats fine.

Regards,

Elfving