system devicetree should support describing a board w/multiple different SoCs

[galak]

An example from the MCU world is the 96board Carbon in which we have a ST STM32F401 and Nordic NRF 51822. The NRF is acting as a bluetooth radio.

We should have some means to utilize SoC dtsi files and compose a single system devicetree that represents the boards and the connections between the various Soc's (in this case via SPI).

[galak]

FYI @mbolivar-nordic, @carlescufi

[carlescufi]

Completely agree with the premise. This of course should also include shared memory if any.

[mbolivar-nordic]

Having become more familiar with the system DT specification, I think it would be challenging to do this. There doesn't seem to be a clean way to compose system devicetrees. The main challenges are related to namespace management. Consider that CPU clusters, as top level nodes, share a namespace. So if we want to be able to compose a system devicetree by #include of other SoC level system devicetrees, there is the potential for two CPU clusters with the same name to conflict. A similar problem exists in the /domains node.

I think this issue should be closed. As I have already communicated internally within the zephyr project efforts for this, I believe this is a non-goal for an initial effort.