Clarification on migrating from Partition Manager to Devicetree

RE: Clarification on migrating from Partition Manager to Devicetree

Ken58 — Tue, 23 Jun 2026 00:16:13 GMT

Thanks for all your help Simon. I appreciate it very much.

Have a great day,

Ken

RE: Clarification on migrating from Partition Manager to Devicetree

Simonr — Mon, 22 Jun 2026 12:02:32 GMT

Hi again

Sorry Ken, you're right. Sloppy math on my end.

2. All addresses from 0x000E0000-0x00100000 are taken by the USB bootloader (including the bootloader settings page and MBR parameter storage). This is also stated in the Dongle Programming tutorial for reference, so these can not be used as storage.

Best regards,

Simon

RE: Clarification on migrating from Partition Manager to Devicetree

Ken58 — Sat, 20 Jun 2026 14:23:03 GMT

Hi SImonr,

On your point 2. above: 1MB of flash = 1024kB which is actually 1048576 bytes of flash ranging from address 0x00000000 to 0x000FFFFF. Therefore, I think there are two flash pages missing from the partitioning and comments in the nrf52840dongle_nrf52840.dts file.

0x00000	0x00FFF	MBR
0x01000	0x0FFFF	BOOT
0x10000	0x75FFF	SLOT 0
0x76000	0xDBFFF	SLOT 1
0xDC000	0xDFFFF	STORAGE
0xE0000	0xFBFFF	USB BOOTLOADER
0xFC000	0xFCFFF	?
0xFD000	0xFDFFF	?
0xFE000	0xFEFFF	SECOND TO LAST PAGE
0xFF000	0xFFFFF	LAST PAGE

One of your customers might be in need of those 8k bytes of flash. 🙂 Maybe those pages are actually in use by the USB boot loader. It is possible I'm missing something or my math is wrong. Perhaps another engineer can check us on this?

I will try to see if I can get blinky to build without the partition manager and let you know what happens. ...As of nRF Connect for VS Code v2026.6.2060, it will build without error with a sysbuild.conf file with SB_CONFIG_PARTITION_MANAGER=n. I'm happy about that.

Thank you,

Ken

RE: Clarification on migrating from Partition Manager to Devicetree

Simonr — Fri, 19 Jun 2026 06:46:15 GMT

Hi again Ken

1. I don't have a good answer with reasoning for you here, as this is a design choice on our end.

2. These page addresses are beyond the 1024 kB of data, so I don't think they are missing.

In addition to following the migration guide, you also need to manually update the flash_layout.h as well. Please refer to this commit: https://github.com/nrfconnect/sdk-zephyr/commit/e542188ce9c07e89d5d47791ea92a539eb38ab40#diff-a8ef76e5ec93e0a45b8e73ab1aa110c47567fec2bc51166ffb5fb4426e94f7a2R13

Best regards,

Simon

RE: Clarification on migrating from Partition Manager to Devicetree

Ken58 — Thu, 18 Jun 2026 20:20:01 GMT

Hi Simonr,

Thanks for getting back to me. It's summer and many people are on holiday. The remaining questions I have regarding the default nrf52840dongle_nrf52840.dts:

Why not list the partitions used for the MBR, USB bootloader, and last and second to last flash pages like the other partitions listed rather than only making this visible in the comments? I think they can be specified as read only if needed.
There are 2 pages of flash not accounted for in that file, specifically bytes at address 0x000FC000 through 0x000FDFFF. Should this be corrected in the file?

Also, I have not been able to build my application successfully with the Partition Manager disabled within nRF Connect for VS Code. So, taking the Nordic blinky example, which still uses the Partition Manager in V3.3.0, how would I disable it and successfully build?

Thank you,

Ken

RE: Clarification on migrating from Partition Manager to Devicetree

Simonr — Mon, 15 Jun 2026 07:47:41 GMT

Just to give you an update. There is no reason to think any big changes will come to the current version of the nrf52840dongle board file. The latest updated version of the file can be found here: https://github.com/nrfconnect/sdk-zephyr/blob/main/boards/nordic/nrf52840dongle/nrf52840dongle_nrf52840.dts

We can't guarantee there won't be changes in the future, but per now, there are no plans of that at least, and this is the file you should refer to when migrating to a new SDK version.

Best regards,

Simon

RE: Clarification on migrating from Partition Manager to Devicetree

Simonr — Fri, 12 Jun 2026 10:31:51 GMT

Hi Kenneth

If your project is running on the nRF52840 Dongle, I'd recommend you use the default board/.dts file from the SDK version you're using after a merge. The python script doesn't seem to have made separate partitions for the MBR, Bootloader, and slot partitions.

The built in USB bootloader is indeed not part of MCUBoot, please see the Dongle documentation for more information on that.

We will also be getting back to you on the questions Maria is looking into.

For your last question, there are no planse to change the Dongle DTS files further AFAIK. Do you see any reason they should be changed?

Best regards,

Simon

RE: Clarification on migrating from Partition Manager to Devicetree

Ken58 — Fri, 05 Jun 2026 00:44:41 GMT

And also, don't forget the question regarding default partitioning in the nrf52840dongle_nrf52840.dts. Are these going to change, and if so, to what. The nrf52840 Dongle and DK would be good examples.

RE: Clarification on migrating from Partition Manager to Devicetree

Ken58 — Tue, 02 Jun 2026 21:01:14 GMT

Hi Maria,

Thanks for the response. However, regarding my first question on the content of the overlay created by the python script and the default nRF52840 Dongle partitioning. What should I end up with as a merged version of these partitions?

After more research on the topic, I think that any Zephyr device tree partitioning for a nRF52840 Dongle would have to do the following:

Reserve flash address 0x00000000 to 0x00000FFF for the MBR (as shown in the python script output)
Reserve flash address 0x000E0000 to 0x000FDFFF for the built in USB bootloader. (This assumes that one would want to retain the factory programming of the device) This address range is different in size from what the ..\v3.3.0\zephyr\boards\nordic\nrf52840dongle\nrf52840dongle_nrf52840.dts comments indicate. That would be address 0x000E0000 to 0x000FBFFF. Which is correct? Also, what is the "built in USB bootloader"? I don't think it is a part of MCUboot. I can't find any specific documentation at Nordic describing it. Is there something you can point to?
What is going on in the topmost flash addresses: 0x000FE000 or FC000 through 0x000FFFFF?

I hope you can answer these questions.

Thanks,

Ken

RE: Clarification on migrating from Partition Manager to Devicetree

Maria Gilje — Mon, 01 Jun 2026 16:54:14 GMT

Hi Ken,

[quote user=""]Will the default nrf52840dongle_nrf52840.dts in future versions of the SDK be modified for this partitioning?[/quote]

I'll check this internally and get back to you.

[quote user=""]How and where should I set CONFIG_PARTITION_MANAGER_ENABLED=n ? I thought .config.sysbuild is generated by the SDK and should not be directly modified.[/quote]

You can set it in the sysbuild.conf for you application, or pass it as an extra CMake option like described in step 7 here: https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/releases_and_maturity/migration/migration_partitions.html#migrate_your_project_to_dts-partitioning

west build -p \
  -b <board_target> \
  <app_or_test_path> \
  -- \
  -DSB_CONFIG_PARTITION_MANAGER=n

Best regards,

Maria