I applied through the website and submitted a cv and covering letter. I tailored it specifically for the role - say, if you apply for the operating systems team, give them examples of how you have been involved - GitHub accounts and code repositories are great. I was contacted by email from HR a few weeks later(1 or 2 at most they were quick ). The HR staff were both very friendly and professional and made the whole thing extremely pleasant - I was scheduled a phone interview with an ARM engineer. The interview was technical but also had soft skills questions(give me a situation where...). For the technical bit expect overall low level computing questions - c, c++, data structures, computer architecture questions (if you don't know what's a super scalar you shouldn't be a developer in ARM). A few days after the phone interview HR contacted me again to ask for my preferences for the assessment centre day. On the assessment day, HR gave us an intro lecture and were again very friendly.Each role had specific interviews

1st was a hirevue interview - basic behavioral questions 2nd round was a panel interview - discussion on your resume and technical questions related to power and designing low power circuits