This is hardly a theoretical question as many have done this, albeit there's very little information on the underlying processes.

I'm developing a custom MIPS-based processor on which I would like to run ubuntu. I'm quite baffled as to what to do next after you've designed the instruction set and the computer architecture itself. I need to be able to run a kernel and OS but how does it all tie in? At the moment I'm researching into designing a compiler for the linux kernel to generate the appropriate assembly language. Is that a good way to go? What do I need to do after that?