I applied online. The process took 4 weeks. I interviewed at Arm (Cambridge, England) in Feb 2017
Interview
After a digit interview, I got a face-to-face interview, the interviewers are nice, give me a lot of help, they asked about my project, my programming skills, and as well as technical questions which is related to the group. First round is technical, second one is more casual, more about my personal projects. I think they are more interested in your thoughts, abilities rather than deep understanding of some language.