Using Zephyr NVS with mcuboot - losing configuration on firmware update

[jbrzozoski]

I've got my application wrapped in mcuboot for HTTP-based firmware updates which is working fine.  In the past couple days I've enabled CONFIG_NVS using the code in zephyr/samples/subsys/nvs for guidance.  The basic ability to save/load settings works fine, and values are retained around power cycles as expected.  However, I've not been able to save NVS settings around firmware updates, either locally via nrfjprog or remotely via mcuboot.

I am using the default partition manager settings for the nrf9160_pac10090/nrf9160_pac10090ns board, and am building my application targeting nrf9160_pac10090ns.

I double-checked the parameters I'm passing to nvs_init(), and I am using an offset of DT_FLASH_AREA_STORAGE_OFFSET (1024000) with 3 sectors of size 0x1000.  These values all seem to safely align with the FLASH offset/size ranges I'm finding in the generated DTS files in my build output directory, both for mcuboot and my application.

My libraries are all checked matching the manifest in NRF at tag v0.4.0.

I've noticed that the fs_nvs log shows slightly different values on reboot after a mcuboot swap, which makes me think mcuboot is touching the storage flash.

For example, after a full device erase, with nothing stored, I see this on bootup:

[00:00:01.819,976] <inf> fs_nvs: 3 Sectors of 4096 bytes
[00:00:01.825,744] <inf> fs_nvs: alloc wra: 0, ff0
[00:00:01.830,993] <inf> fs_nvs: data wra: 0, 0

After writing one value to NVS, I see this on bootup:

[00:00:00.457,641] <inf> fs_nvs: 3 Sectors of 4096 bytes
[00:00:00.463,409] <inf> fs_nvs: alloc wra: 0, fe8
[00:00:00.468,658] <inf> fs_nvs: data wra: 0, 5

And then, after mcuboot swap, I see this on bootup:

[00:00:00.453,277] <inf> fs_nvs: 3 Sectors of 4096 bytes
[00:00:00.459,045] <inf> fs_nvs: alloc wra: 1, ff0
[00:00:00.464,263] <inf> fs_nvs: data wra: 1, 348

Any suggestions on what I might be doing wrong or where to look next?

[jbrzozoski]

Just found my issue: the DTS and partition manager break up flash differently.  The mcuboot is relying on the PM layout while my NVS code was using the DTS layout.

I changed my NVS offset from DT_FLASH_AREA_STORAGE_OFFSET to PM_MCUBOOT_STORAGE_ADDRESS and mcuboot is no longer wiping out my config.  nrfjprog is still erasing all of flash, but that's acceptable as long as I'm aware of that.

[phipi]

If you specify --sectorerase (ie nrfjprog.exe --program zephyr/merged.hex --sectorerase && nrfjprog.exe -r) it will only erase as much as it needs to in order to replace your application and allow you to keep your settings.

I know this is old but I just stumbled across it while searching for something else and thought maybe this will help someone in the future.