Phone interview was pre-screening and I was mostly asked behaviour questions and about past experiences. There were a couple of technical questions about C and operating systems, like what is the difference between real-time OS and general OS. Second interview went quite the same way. We talked about previous projects. The interviewer tried to challenge by throwing many question on the projects we discussed. They were very heavy on process and documentation. Like what is the name of this document that you wrote? Then they asked to write a small code in C, to flip a string. They asked a few questions about operating systems, e.g. process/thread/synchronization.