After doing the apply on arm website I received first a call on phone in December than they invite me to a face to face interview in cambridge in january (flights hotel and taxis paid by ARM)

first arrange time for the phone interview over email. the interview lasts about 30 to 45 minutes. the interview is basically based on my resume. questions are related to the details about my projects, including concepts and software I used. in addition, they asked some questions about linux commands, perl syntax, etc