The patch is to fix the early termination in multi-core simulation under SE mode. When "-I" (maximum instruction number) and "-F" (fastforward instruction number) are applied together, gem5 immediately exits after the cpu switching. The reason is that multiple exit events may be generated in the same cycle by Atomic CPU and inserted to mainEventQueue. However, mainEventQueue can only serve one exit event in one cycle. Therefore, the rest exit events are left in mainEventQueue without being descheduled or deleted, which causes gem5 exits immediately after the system resumes by cpu switching.

Test done by spec2006 simulation