There were three rounds.

First round:

• Introduction: Tell me about yourself.
• Questions regarding my current role and past projects.
• Fundamentals of OS and C:
  • Deadlocks
  • IPC mechanisms
  • Threads
  • Shared memory
  • Structured padding
  • malloc vs. calloc
  • Wild pointers
  • Segmentation
  • Paging vs. swapping
  • Friend classes, etc.

The interviewer then asked me to wait for five minutes in the call for the next round.

Second round:

• Introduction again.
• A few OS basics were asked.
• Then, I was asked to write C code for the synchronization of two threads.

Manager Round:

• This was the last round.
• The manager asked about my past experiences and briefly explained the role for which they were hiring.
• He asked if I had thought about or completed any innovative projects.

Even though my technical rounds went very well, I think the manager was not very happy with my answers, so I didn't get an offer.