Mad C Skillz OEMG

I want to jump to the next level in C. I'm a quite skilled programmer for what I do, know the whole K&R but I feel like I miss something, especially about those weird techniques proPROgrammers use in OS dev and related. Suggested readings?

>>34
It's a toy system that is not worth my time. Many of it "innovations" are just poor and late reimplementations of what already existed in the Unix world.