Lab 3: Checklist

  1. If you take the saved pc in the stack frame for main and subtract it from the saved lr in the stack frame for diff, what do you get? Express your answer as a number, then explain conceptually what that computation represents.

  2. Why will loopback mode only work if you plug in both TX and RX?

  3. Running bare metal on the Pi as we do, there is no circumstance under which an invalid call to strlen (e.g. argument is an invalid address or unterminated string) has a visible bad consequence at runtime. Why not?