There were 3 phone interviews. 1 was hard and other 2 were simple. The hard one went into several technical quiz like questions. The simple ones had me describe a pipeline and asked questions on projects done from the resume. On the day of the interview, I arrived at 10AM. There were 5 interviews. I did well on 3 which went into details on CPU arch. However 2 of them were focused on interactions betweem drivers and kernel, kernel in general and GPU drivers. Not having worked in that area, I didn't do well.