[oe] minimal template layer for new machine support

[Tilman Baumann]

Hi,

I'm working on a TI DM812x support overlay.
I guess what it comes down to is a new kernel recipe (based on TI's 
sources) and this funny two stage u-boot.
I think I can write the recipes. But what I don't quite see is how I 
would add a new supported machine in the first place?
I was trying to orient myself on a few existing machine support layers. 
But I think I'm still missing the point.
What are the minimal basics to implement? Where should I start?

Thanks for any help.

Cheers
  Tilman