I got the interview invite through employee referral. The interview was for straight 3hours online due to the pandemic. First round : Basic c, pointers and couple of programming questions . I did this really well. Second round: This was a disaster. The interviewer looked like an OS expert. He started asking all the OS definitions he studied in college. There was no application related questions. If you know the definition you can answer else its a plain no. I dint like the pattern of this interview. He kept shooting barrage of definition questions. Overall a very difficult round. I had been attending few interviews recently and this was the most difficult and most bizarre round. Third round: This round was based on the protocols I know like pcie, usb, i2c spi etc. Also few Linux related questions. I did well in this round too.