Most don't do anything. Make default_event() return a dummy event to avoid dereferencing a null pointer. Change-Id: I8d6d576d3a1f585029c387cd414bbebf2d670644 Reviewed-on: https://gem5-review.googlesource.com/12072 Reviewed-by: Gabe Black <gabeblack@google.com> Maintainer: Gabe Black <gabeblack@google.com>