Are you familiar with a recursion function? If so, can you discuss when to use it and what happens when it is declared inline?

When writing firmware code, you will use a wide variety of functions and other lines of code. Interviewers are likely to ask you about some of these to test your knowledge and confirm that you have worked with firmware in your previous roles. While you can't be familiar with all the functions and lines of code used in firmware, you should be familiar with the most common ones and be able to describe them. If you are asked about something you are unfamiliar with, state that, then describe to the interviewer how you would research it.