It starts from phone screens , sometimes they go for more than one screening as they bring out peope to interview with 2-3 different teams which is one reason it takes time. It took three weeks after i was said in first phone screen that interviewer is recommending me for onsite and I should here something from HR within few days to get second interview and finally was called for full day onsite interview. Phone screens are typical and have some basic questions from volatile , static to some RTOS concepts. There was one interview with staffing specialist explaining the procedure and recruitment process, benefits , and after that had 5 1:1 interviews 2 with security team and 3 with Core-BSP and device drivers team
Lot of board work , some engineer asked to write code on his computer