sysbuild: impossible to include an overlay for all projects in a multi-image build

[jameswalmsley]

Describe the bug
I'm trying to create a concrete sysbuild example including bootloader, factory image and main image to help people get started with zephyr, and especially using sysbuild.

Either I'm not understanding how it works, or sysbuild is missing some fundamental features!

My issue is I need to override the partition layout of a nucleo board, and I cannot do this without manually specifying the same overlay file to each project on the commandline. This seems like an anti-pattern.

Is there something I'm missing?

I was expecting that I'd be able to add a sysbuild/boards/nucleo_f413zh.overlay file or similar that would be picked up and applied to all the projects, but thats not the case.

My command line

west build --sysbuild sysbuild-example \
    -DEXTRA_DTC_OVERLAY_FILE=sysbuild-example/overlays/nucleo_f413zh_partitions.overlay \
    -Dmcuboot_EXTRA_DTC_OVERLAY_FILE=sysbuild-example/overlays/nucleo_f413zh_partitions.overlay \
    -Dmfg_image_EXTRA_DTC_OVERLAY_FILE=sysbuild-example/overlays/nucleo_f413zh_partitions.overlay \
    -Ddfu_app_EXTRA_DTC_OVERLAY_FILE=sysbuild-example/overlays/nucleo_f413zh_partitions.overlay

Impact
This makes the use of sysbuild rather limited. Sysbuild should support this scenario for companies using zephyr to build entire systems.

I'd be happy to provide a PR to make this work, if someone could give me some pointers.

[nordicjm]

If you need to define a different partition layout then you should be extending the board instead https://docs.zephyrproject.org/latest/hardware/porting/board_porting.html#board-extensions or creating a new board which has the expected partition layout, this is not a sysbuild bug/problem and is by design

[jameswalmsley]

Thanks for the pointer @nordicjm..

That should do what I need, I'll close this ticket.

[jameswalmsley]

Hi @nordicjm I'm re-opening this, because I've started implementing a board extension for my example, and wanted your advice.

I can create an extension, and west picks up the new dts file.

However it seems to replace the original board DTS file entirely. Is it possible to extend an existing board with an overlay?

Under the extend_board tests I saw one variant #include the other variant. Its also not possible to #include a dts from the original board folder. (Probably less desirable than an actual overlay IMO).

Feels like I'm missing something, as I was expecting to have the full original board definition and be able to "extend" it with an overlay, but this sems to replace it instead.

I'll be happy to make a PR to update the documentation when I understand how to do this :)