Just know the intricacies of the C programming language. Know what static means within a function, and when declared on a global variable. Know terms like deadlock, re-entrant, semaphore, etc. This was just a screening interview to make sure you knew some stuff. None of the questions were really that difficult. There was one generic programming question where they had you write out some code. It was simple, but pay attention to what you're doing. There's just little details they look for. They'll help you with them if you don't see them immediately.
