Hello,
I have an issue when trying to use NVS backend for BLE settings with the settings_storage partition in defined external flash region. As we are doing a multi-image build, the partition manager is enabled and adds the settings_storage partition automatically when building with settings enabled, which defaults to flash_primary region. What we want to achieve is be able to put this partition in external flash to save space in internal flash.
I'm using nrf5340 custom board, but I tried it on nrf5340 DK and I observed the exact same issue, so I doubt it is related to hardware. I'm using NCS 2.0.2.
The issue :
When calling bt_enable() with settings enabled, the device seems to get stuck in sysworkq thread (observed with SystemView) for a few minutes without crashing. See here :
As you can observe, the logging that tells to call settings_load gets preempted for a few minutes (around 10 minutes), and then initialization continues, bt_enable() returns with success, so we call settings_load() which fails with this error that is spammed in logs :
What I did in my pm_static.yml file is that I redefined settings_storage partition to be in external flash, like this:
data: address: 0x0 size: 0x60000 device: MX25R64 region: external_flash settings_storage: address: 0x60000 size: 0x20000 device: MX25R64 region: external_flash mcuboot_secondary: address: 0x80000 size: 0xec000 device: MX25R64 region: external_flash mcuboot_secondary_1: address: 0x16c000 size: 0x40000 device: MX25R64 region: external_flash littlefs_storage: address: 0x1ac000 size: 0xe54000 device: MX25R64 region: external_flash external_flash: address: 0x1000000 size: 0x0 device: MX25R64 region: external_flash
I can use all these partitions without any issue, perform MCUboot DFU on both cores with images on external flash, use filesystem (LittleFS) and data partition with flash_area API. If we use file system backend for settings it works well, but we would to prefer not using the filesystem for that.
I tried to erase the QSPI external flash completely see if it solves any issues, but I still have the same issue.
If I leave the partition to flash_primary with NVS settings backend, I don't observe any of these issues, everything works as expected. I saw that every NCS sample keeps this partition in flash_primary in the PM static config, and I was wondering if it has been tested with external flash and if it's supposed to work or even recommended.
And also, if we have to go with internal flash, by default the settings_partition in only 8 kB. Is that enough if it's only used for BLE settings ?
