Bingup the new platform not in Linux repository

about portint doc:(Porting seL4 to a new platform | seL4 docs)

“You may need to add device nodes depending on what Linux uses and what is required by
seL4. For example, in the port of the Rockpro64 a memory node and an extra timer node were
needed so these had to be defined manually.”

how can I get the required by seL4? have any doc about it? what’s node is must?