ruby: set SimpleTiming as the default cpu
ruby: set SimpleTiming as the default cpu

andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin