Can I update the SoftDevice without touching the application?

[Elias]

I'm working on an OTA firmware update process, using my own bootloader and application. To understand the process' limitations, I need to know to what extent one can update the SoftDevice without invalidating the application.

The chart on the nrfutil GitHub seems to imply that I can update a SoftDevice without updating the app as long as both SDs are of the same Major Version, e.g. s132 v3.0 to v3.1, presumably because Nordic preserves APIs (and the locations they reference in the SD) across these. Updating from v3.0 to 4.0, though, would require a new application. Correct?

Furthermore, can I safely assume that the Master Boot Record will remain compatible with all future SoftDevice versions? I understand that I need to leave it alone across any update, since without it, there is nothing to decide whether to jump to a bootloader or application.

[Hung Bui]

When you update your softdevice, the application will be erase to give space for the new image of the softdevice. You will have to update the application back after you done with the softdevice.

Between minor versions of the softdevice, the application doesn't need to be modified to work with the new softdevice (with same major version).

We will try to keep the MBR unchanged alongside same softdevice in different major versions.