Ask HN: how do Microsoft do Continuous integration for windows OS?

Was curious about how Microsoft organize their continuous integration for windows OS. I'm sure I remember reading a blog post about it somewhere, but I can't find it now.

Specifically, Can developers check out all of windows and reasonably expect to build it on their desktop machines? or is it simply too large. Part of my thinks "you can do it with a linux kernel, why not?", and part of me thinks "windows has got to be a beast - it probably takes years to compile on a desktop machine"

Given it's a pretty massive product, I'm interested in hearing from Ex or current microsofters about how they organize it, particularly around change, so if you are on the file system team, and you submit a change, how agile/quickly can you get feedback as to whether it's worked on not?