I'm out of ideas (I will communicate with Takashi). I thought it would be the first get_cycle_time() to crash. But apparently, there are several calls to it and it goes on. Until "something" happens. One final check from me -- I let get_cycle_time() to always dump a single line (not a stack trace as before) and return 0 without accessing the timestamp reg. Could you check this really avoids the problem?