dts: nrf52840_pca10059: No convenient way to use "fstab-debugger.dts"

[MarekPieta]

DTS for nrf52840_pca10059 has no way to use "fstab-debugger.dts" (flash partition table without Nordic nRF5 bootloader). Currently we may only modify dts for the board in Zephyr (changing included file), but it isn't a good solution. Eventually we may delete the nodes in overlay and re-create it for our application.

[lemrey]

You can use the fstab-debugger.dts by including it in the board DTS file; that will work as documented, so the issue title is incorrect. This is not really a problem with this specific board, and it is a consequence of Zephyr's model. I agree with the bottomline here, but I think that should be discussed in a broader context.

[carlescufi]

Changing to enhancement since this is expected although can be improved.

[jcorde]

Using fstab-debugger.dts is not enough as BOARD_HAS_NRF5_BOOTLOADER is still selected by Kconfig. So Kconfig.defconfig sets FLASH_LOAD_OFFSET to 0x1000.

[jcorde]

If we follow Programming Option 3 - External debug probe, the offset will not be set to 0x000.

[crespum]

Using fstab-debugger.dts is not enough as BOARD_HAS_NRF5_BOOTLOADER is still selected by Kconfig. So Kconfig.defconfig sets FLASH_LOAD_OFFSET to 0x1000.

This is correct but it's only slightly related to the original issue. We could just improve the documentation IMHO.

To use an external debugging probe:

1. Edit nrf52840dongle_nrf52840.dts and replace fstab-stock.dts by fstab-debugger.dts.
2. Run make menuconfig
   1. Disable BOARD_HAS_NRF5_BOOTLOADER
   2. Set FLASH_LOAD_OFFSET to 0

In any case, shall I open a new issue or even a new PR?

[carlescufi]

This is currently being covered by #40669, but I will send a PR for the doc. Actually, there's no need, the doc already covers what needs to be done.