I know there is https://github.com/haiku/haiku/tree/master/docs/develop/ports/arm https://github.com/haiku/haiku/tree/master/docs/develop/port... but I think it

I know there is https://github.com/haiku/haiku/tree/master/docs/develop/ports/arm https://github.com/haiku/haiku/tree/master/docs/develop/port... but I think it's out of date at this point. Check the commit logs for the "arm" directories in the kernel, and then ask the developers responsible for that on IRC (Freenode#haiku). I don't know much about the ARM port in specific, but I'm very familiar with our build system and development model in general, so if you have questions about that I can help there.