stdlib, configs: Migrate riscv-ubuntu-run example to Simulator

Change-Id: Ie08fcf46139871bc98b9bf783d0b4d9913eace3e
Signed-off-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/58790
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>

configs/example/gem5_library/riscv-ubuntu-run.py

@@ -53,6 +53,7 @@ from gem5.components.processors.cpu_types import CPUTypes
 from gem5.isas import ISA
 from gem5.coherence_protocol import CoherenceProtocol
 from gem5.resources.resource import Resource
+from gem5.simulate.simulator import Simulator
 
 # This runs a check to ensure the gem5 binary is compiled for RISCV.
 
@@ -116,32 +117,5 @@ board.set_kernel_disk_workload(
 
 root = Root(full_system=True, system=board)
 
-m5.instantiate()
-
-# We simulate the system till we encounter `m5_exit instruction encountered`.
-
-exit_event = m5.simulate()
-
-# We check whether the simulation ended with `m5_exit instruction encountered`
-
-if exit_event.getCause() == "m5_exit instruction encountered":
-    # We acknowledge the user that the boot was successful.
-
-    print("Successfully completed booting!")
-else:
-    # `m5_exit instruction encountered` was never encountered. We exit the
-    # program unsuccessfully.
-
-    print("The startup was not completed successfully!",)
-    print(
-    "Exiting @ tick {} because {}."\
-        .format(m5.curTick(), exit_event.getCause())
-    )
-    exit(-1)
-
-# We are done with the simulation. We exit the program now.
-
-print(
-"Exiting @ tick {} because {}."\
-    .format(m5.curTick(), exit_event.getCause())
-)
+simulator = Simulator(board=board)
+simulator.run()