How to compile kernel modules

[jottr]

I've been trying to get Nixos fully running on a Macbook Pro 13,1.
Two drivers need to be patched to get this working.
There are very little resources on how to best approach this in Nixos.
All I could find is this wiki page, and these 1 2 forum posts, as well as this example in the manual on how to develop kernel modules.

Since patching kernels or kernel modules is a non-trivial topic that has not been covered in depth by blog posts or tutorial videos, it would be awesome if you could make this a topic of one of your next nix-hours.
In case this is not part of your expertise, maybe someone that is part of the nixos contributors would be willing to share their experience.

A few things that could get covered:

• difference of in- and out-of-tree kernel modules
• how to setup a kernel development environment
• how to obtain kernel sources
• how to generate a patch and apply it to the kernel source
• how to make it a nix module following best practices
• how to test the module