configs/example/arm/fs_bigLITTLE.py - testing/jenkins-gem5-prod - Git at Google

 # Copyright (c) 2016-2017 ARM Limited
 # All rights reserved.
 #
 # The license below extends only to copyright in the software and shall
 # not be construed as granting a license to any other intellectual
 # property including but not limited to intellectual property relating
 # to a hardware implementation of the functionality of the software
 # licensed hereunder.  You may use the software subject to the license
 # terms below provided that you ensure that this notice is replicated
 # unmodified and in its entirety in all distributions of the software,
 # modified or unmodified, in source code or in binary form.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met: redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer;
 # redistributions in binary form must reproduce the above copyright
 # notice, this list of conditions and the following disclaimer in the
 # documentation and/or other materials provided with the distribution;
 # neither the name of the copyright holders nor the names of its
 # contributors may be used to endorse or promote products derived from
 # this software without specific prior written permission.
 #
 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #
 # Authors: Gabor Dozsa
 #          Andreas Sandberg

 # This is an example configuration script for full system simulation of
 # a generic ARM bigLITTLE system.


 from __future__ import print_function

 import argparse
 import os
 import sys
 import m5
 import m5.util
 from m5.objects import *

 m5.util.addToPath("../../")

 from common import SysPaths
 from common import CpuConfig
 from common.cores.arm import ex5_big, ex5_LITTLE

 import devices
 from devices import AtomicCluster, KvmCluster


 default_kernel = 'vmlinux4.3.aarch64'
 default_disk = 'aarch64-ubuntu-trusty-headless.img'
 default_rcs = 'bootscript.rcS'

 default_mem_size= "2GB"

 def _to_ticks(value):
     """Helper function to convert a latency from string format to Ticks"""

     return m5.ticks.fromSeconds(m5.util.convert.anyToLatency(value))

 def _using_pdes(root):
     """Determine if the simulator is using multiple parallel event queues"""

     for obj in root.descendants():
         if not m5.proxy.isproxy(obj.eventq_index) and \
                obj.eventq_index != root.eventq_index:
             return True

     return False


 class BigCluster(devices.CpuCluster):
     def __init__(self, system, num_cpus, cpu_clock,
                  cpu_voltage="1.0V"):
         cpu_config = [ CpuConfig.get("O3_ARM_v7a_3"), devices.L1I, devices.L1D,
                     devices.WalkCache, devices.L2 ]
         super(BigCluster, self).__init__(system, num_cpus, cpu_clock,
                                          cpu_voltage, *cpu_config)

 class LittleCluster(devices.CpuCluster):
     def __init__(self, system, num_cpus, cpu_clock,
                  cpu_voltage="1.0V"):
         cpu_config = [ CpuConfig.get("MinorCPU"), devices.L1I, devices.L1D,
                        devices.WalkCache, devices.L2 ]
         super(LittleCluster, self).__init__(system, num_cpus, cpu_clock,
                                          cpu_voltage, *cpu_config)

 class Ex5BigCluster(devices.CpuCluster):
     def __init__(self, system, num_cpus, cpu_clock,
                  cpu_voltage="1.0V"):
         cpu_config = [ CpuConfig.get("ex5_big"), ex5_big.L1I, ex5_big.L1D,
                     ex5_big.WalkCache, ex5_big.L2 ]
         super(Ex5BigCluster, self).__init__(system, num_cpus, cpu_clock,
                                          cpu_voltage, *cpu_config)

 class Ex5LittleCluster(devices.CpuCluster):
     def __init__(self, system, num_cpus, cpu_clock,
                  cpu_voltage="1.0V"):
         cpu_config = [ CpuConfig.get("ex5_LITTLE"), ex5_LITTLE.L1I,
                     ex5_LITTLE.L1D, ex5_LITTLE.WalkCache, ex5_LITTLE.L2 ]
         super(Ex5LittleCluster, self).__init__(system, num_cpus, cpu_clock,
                                          cpu_voltage, *cpu_config)

 def createSystem(caches, kernel, bootscript, disks=[]):
     sys = devices.SimpleSystem(caches, default_mem_size,
                                kernel=SysPaths.binary(kernel),
                                readfile=bootscript)

     sys.mem_ctrls = [ SimpleMemory(range=r, port=sys.membus.master)
                       for r in sys.mem_ranges ]

     sys.connect()

     # Attach disk images
     if disks:
         def cow_disk(image_file):
             image = CowDiskImage()
             image.child.image_file = SysPaths.disk(image_file)
             return image

         sys.disk_images = [ cow_disk(f) for f in disks ]
         sys.pci_vio_block = [ PciVirtIO(vio=VirtIOBlock(image=img))
                               for img in sys.disk_images ]
         for dev in sys.pci_vio_block:
             sys.attach_pci(dev)

     sys.realview.setupBootLoader(sys.membus, sys, SysPaths.binary)

     return sys

 cpu_types = {
     "atomic" : (AtomicCluster, AtomicCluster),
     "timing" : (BigCluster, LittleCluster),
     "exynos" : (Ex5BigCluster, Ex5LittleCluster),
 }

 # Only add the KVM CPU if it has been compiled into gem5
 if devices.have_kvm:
     cpu_types["kvm"] = (KvmCluster, KvmCluster)


 def addOptions(parser):
     parser.add_argument("--restore-from", type=str, default=None,
                         help="Restore from checkpoint")
     parser.add_argument("--dtb", type=str, default=None,
                         help="DTB file to load")
     parser.add_argument("--kernel", type=str, default=default_kernel,
                         help="Linux kernel")
     parser.add_argument("--disk", action="append", type=str, default=[],
                         help="Disks to instantiate")
     parser.add_argument("--bootscript", type=str, default=default_rcs,
                         help="Linux bootscript")
     parser.add_argument("--cpu-type", type=str, choices=cpu_types.keys(),
                         default="timing",
                         help="CPU simulation mode. Default: %(default)s")
     parser.add_argument("--kernel-init", type=str, default="/sbin/init",
                         help="Override init")
     parser.add_argument("--big-cpus", type=int, default=1,
                         help="Number of big CPUs to instantiate")
     parser.add_argument("--little-cpus", type=int, default=1,
                         help="Number of little CPUs to instantiate")
     parser.add_argument("--caches", action="store_true", default=False,
                         help="Instantiate caches")
     parser.add_argument("--last-cache-level", type=int, default=2,
                         help="Last level of caches (e.g. 3 for L3)")
     parser.add_argument("--big-cpu-clock", type=str, default="2GHz",
                         help="Big CPU clock frequency")
     parser.add_argument("--little-cpu-clock", type=str, default="1GHz",
                         help="Little CPU clock frequency")
     parser.add_argument("--sim-quantum", type=str, default="1ms",
                         help="Simulation quantum for parallel simulation. " \
                         "Default: %(default)s")
     parser.add_argument("-P", "--param", action="append", default=[],
         help="Set a SimObject parameter relative to the root node. "
              "An extended Python multi range slicing syntax can be used "
              "for arrays. For example: "
              "'system.cpu[0,1,3:8:2].max_insts_all_threads = 42' "
              "sets max_insts_all_threads for cpus 0, 1, 3, 5 and 7 "
              "Direct parameters of the root object are not accessible, "
              "only parameters of its children.")
     return parser

 def build(options):
     m5.ticks.fixGlobalFrequency()

     kernel_cmd = [
         "earlyprintk=pl011,0x1c090000",
         "console=ttyAMA0",
         "lpj=19988480",
         "norandmaps",
         "loglevel=8",
         "mem=%s" % default_mem_size,
         "root=/dev/vda1",
         "rw",
         "init=%s" % options.kernel_init,
         "vmalloc=768MB",
     ]

     root = Root(full_system=True)

     disks = [default_disk] if len(options.disk) == 0 else options.disk
     system = createSystem(options.caches,
                           options.kernel,
                           options.bootscript,
                           disks=disks)

     root.system = system
     system.boot_osflags = " ".join(kernel_cmd)

     if options.big_cpus + options.little_cpus == 0:
         m5.util.panic("Empty CPU clusters")

     big_model, little_model = cpu_types[options.cpu_type]

     all_cpus = []
     # big cluster
     if options.big_cpus > 0:
         system.bigCluster = big_model(system, options.big_cpus,
                                       options.big_cpu_clock)
         system.mem_mode = system.bigCluster.memoryMode()
         all_cpus += system.bigCluster.cpus

     # little cluster
     if options.little_cpus > 0:
         system.littleCluster = little_model(system, options.little_cpus,
                                             options.little_cpu_clock)
         system.mem_mode = system.littleCluster.memoryMode()
         all_cpus += system.littleCluster.cpus

     # Figure out the memory mode
     if options.big_cpus > 0 and options.little_cpus > 0 and \
        system.littleCluster.memoryMode() != system.littleCluster.memoryMode():
         m5.util.panic("Memory mode missmatch among CPU clusters")


     # create caches
     system.addCaches(options.caches, options.last_cache_level)
     if not options.caches:
         if options.big_cpus > 0 and system.bigCluster.requireCaches():
             m5.util.panic("Big CPU model requires caches")
         if options.little_cpus > 0 and system.littleCluster.requireCaches():
             m5.util.panic("Little CPU model requires caches")

     # Create a KVM VM and do KVM-specific configuration
     if issubclass(big_model, KvmCluster):
         _build_kvm(system, all_cpus)

     # Linux device tree
     if options.dtb is not None:
         system.dtb_filename = SysPaths.binary(options.dtb)
     else:
         system.generateDtb(m5.options.outdir, 'system.dtb')

     return root

 def _build_kvm(system, cpus):
     system.kvm_vm = KvmVM()

     # Assign KVM CPUs to their own event queues / threads. This
     # has to be done after creating caches and other child objects
     # since these mustn't inherit the CPU event queue.
     if len(cpus) > 1:
         device_eq = 0
         first_cpu_eq = 1
         for idx, cpu in enumerate(cpus):
             # Child objects usually inherit the parent's event
             # queue. Override that and use the same event queue for
             # all devices.
             for obj in cpu.descendants():
                 obj.eventq_index = device_eq
             cpu.eventq_index = first_cpu_eq + idx


 def instantiate(options, checkpoint_dir=None):
     # Setup the simulation quantum if we are running in PDES-mode
     # (e.g., when using KVM)
     root = Root.getInstance()
     if root and _using_pdes(root):
         m5.util.inform("Running in PDES mode with a %s simulation quantum.",
                        options.sim_quantum)
         root.sim_quantum = _to_ticks(options.sim_quantum)

     # Get and load from the chkpt or simpoint checkpoint
     if options.restore_from:
         if checkpoint_dir and not os.path.isabs(options.restore_from):
             cpt = os.path.join(checkpoint_dir, options.restore_from)
         else:
             cpt = options.restore_from

         m5.util.inform("Restoring from checkpoint %s", cpt)
         m5.instantiate(cpt)
     else:
         m5.instantiate()


 def run(checkpoint_dir=m5.options.outdir):
     # start simulation (and drop checkpoints when requested)
     while True:
         event = m5.simulate()
         exit_msg = event.getCause()
         if exit_msg == "checkpoint":
             print("Dropping checkpoint at tick %d" % m5.curTick())
             cpt_dir = os.path.join(checkpoint_dir, "cpt.%d" % m5.curTick())
             m5.checkpoint(cpt_dir)
             print("Checkpoint done.")
         else:
             print(exit_msg, " @ ", m5.curTick())
             break

     sys.exit(event.getCode())


 def main():
     parser = argparse.ArgumentParser(
         description="Generic ARM big.LITTLE configuration")
     addOptions(parser)
     options = parser.parse_args()
     root = build(options)
     root.apply_config(options.param)
     instantiate(options)
     run()


 if __name__ == "__m5_main__":
     main()
	# Copyright (c) 2016-2017 ARM Limited
	# All rights reserved.
	#
	# The license below extends only to copyright in the software and shall
	# not be construed as granting a license to any other intellectual
	# property including but not limited to intellectual property relating
	# to a hardware implementation of the functionality of the software
	# licensed hereunder. You may use the software subject to the license
	# terms below provided that you ensure that this notice is replicated
	# unmodified and in its entirety in all distributions of the software,
	# modified or unmodified, in source code or in binary form.
	#
	# Redistribution and use in source and binary forms, with or without
	# modification, are permitted provided that the following conditions are
	# met: redistributions of source code must retain the above copyright
	# notice, this list of conditions and the following disclaimer;
	# redistributions in binary form must reproduce the above copyright
	# notice, this list of conditions and the following disclaimer in the
	# documentation and/or other materials provided with the distribution;
	# neither the name of the copyright holders nor the names of its
	# contributors may be used to endorse or promote products derived from
	# this software without specific prior written permission.
	#
	# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	#
	# Authors: Gabor Dozsa
	# Andreas Sandberg

	# This is an example configuration script for full system simulation of
	# a generic ARM bigLITTLE system.


	from __future__ import print_function

	import argparse
	import os
	import sys
	import m5
	import m5.util
	from m5.objects import *

	m5.util.addToPath("../../")

	from common import SysPaths
	from common import CpuConfig
	from common.cores.arm import ex5_big, ex5_LITTLE

	import devices
	from devices import AtomicCluster, KvmCluster


	default_kernel = 'vmlinux4.3.aarch64'
	default_disk = 'aarch64-ubuntu-trusty-headless.img'
	default_rcs = 'bootscript.rcS'

	default_mem_size= "2GB"

	def _to_ticks(value):
	"""Helper function to convert a latency from string format to Ticks"""

	return m5.ticks.fromSeconds(m5.util.convert.anyToLatency(value))

	def _using_pdes(root):
	"""Determine if the simulator is using multiple parallel event queues"""

	for obj in root.descendants():
	if not m5.proxy.isproxy(obj.eventq_index) and \
	obj.eventq_index != root.eventq_index:
	return True

	return False


	class BigCluster(devices.CpuCluster):
	def __init__(self, system, num_cpus, cpu_clock,
	cpu_voltage="1.0V"):
	cpu_config = [ CpuConfig.get("O3_ARM_v7a_3"), devices.L1I, devices.L1D,
	devices.WalkCache, devices.L2 ]
	super(BigCluster, self).__init__(system, num_cpus, cpu_clock,
	cpu_voltage, *cpu_config)

	class LittleCluster(devices.CpuCluster):
	def __init__(self, system, num_cpus, cpu_clock,
	cpu_voltage="1.0V"):
	cpu_config = [ CpuConfig.get("MinorCPU"), devices.L1I, devices.L1D,
	devices.WalkCache, devices.L2 ]
	super(LittleCluster, self).__init__(system, num_cpus, cpu_clock,
	cpu_voltage, *cpu_config)

	class Ex5BigCluster(devices.CpuCluster):
	def __init__(self, system, num_cpus, cpu_clock,
	cpu_voltage="1.0V"):
	cpu_config = [ CpuConfig.get("ex5_big"), ex5_big.L1I, ex5_big.L1D,
	ex5_big.WalkCache, ex5_big.L2 ]
	super(Ex5BigCluster, self).__init__(system, num_cpus, cpu_clock,
	cpu_voltage, *cpu_config)

	class Ex5LittleCluster(devices.CpuCluster):
	def __init__(self, system, num_cpus, cpu_clock,
	cpu_voltage="1.0V"):
	cpu_config = [ CpuConfig.get("ex5_LITTLE"), ex5_LITTLE.L1I,
	ex5_LITTLE.L1D, ex5_LITTLE.WalkCache, ex5_LITTLE.L2 ]
	super(Ex5LittleCluster, self).__init__(system, num_cpus, cpu_clock,
	cpu_voltage, *cpu_config)

	def createSystem(caches, kernel, bootscript, disks=[]):
	sys = devices.SimpleSystem(caches, default_mem_size,
	kernel=SysPaths.binary(kernel),
	readfile=bootscript)

	sys.mem_ctrls = [ SimpleMemory(range=r, port=sys.membus.master)
	for r in sys.mem_ranges ]

	sys.connect()

	# Attach disk images
	if disks:
	def cow_disk(image_file):
	image = CowDiskImage()
	image.child.image_file = SysPaths.disk(image_file)
	return image

	sys.disk_images = [ cow_disk(f) for f in disks ]
	sys.pci_vio_block = [ PciVirtIO(vio=VirtIOBlock(image=img))
	for img in sys.disk_images ]
	for dev in sys.pci_vio_block:
	sys.attach_pci(dev)

	sys.realview.setupBootLoader(sys.membus, sys, SysPaths.binary)

	return sys

	cpu_types = {
	"atomic" : (AtomicCluster, AtomicCluster),
	"timing" : (BigCluster, LittleCluster),
	"exynos" : (Ex5BigCluster, Ex5LittleCluster),
	}

	# Only add the KVM CPU if it has been compiled into gem5
	if devices.have_kvm:
	cpu_types["kvm"] = (KvmCluster, KvmCluster)


	def addOptions(parser):
	parser.add_argument("--restore-from", type=str, default=None,
	help="Restore from checkpoint")
	parser.add_argument("--dtb", type=str, default=None,
	help="DTB file to load")
	parser.add_argument("--kernel", type=str, default=default_kernel,
	help="Linux kernel")
	parser.add_argument("--disk", action="append", type=str, default=[],
	help="Disks to instantiate")
	parser.add_argument("--bootscript", type=str, default=default_rcs,
	help="Linux bootscript")
	parser.add_argument("--cpu-type", type=str, choices=cpu_types.keys(),
	default="timing",
	help="CPU simulation mode. Default: %(default)s")
	parser.add_argument("--kernel-init", type=str, default="/sbin/init",
	help="Override init")
	parser.add_argument("--big-cpus", type=int, default=1,
	help="Number of big CPUs to instantiate")
	parser.add_argument("--little-cpus", type=int, default=1,
	help="Number of little CPUs to instantiate")
	parser.add_argument("--caches", action="store_true", default=False,
	help="Instantiate caches")
	parser.add_argument("--last-cache-level", type=int, default=2,
	help="Last level of caches (e.g. 3 for L3)")
	parser.add_argument("--big-cpu-clock", type=str, default="2GHz",
	help="Big CPU clock frequency")
	parser.add_argument("--little-cpu-clock", type=str, default="1GHz",
	help="Little CPU clock frequency")
	parser.add_argument("--sim-quantum", type=str, default="1ms",
	help="Simulation quantum for parallel simulation. " \
	"Default: %(default)s")
	parser.add_argument("-P", "--param", action="append", default=[],
	help="Set a SimObject parameter relative to the root node. "
	"An extended Python multi range slicing syntax can be used "
	"for arrays. For example: "
	"'system.cpu[0,1,3:8:2].max_insts_all_threads = 42' "
	"sets max_insts_all_threads for cpus 0, 1, 3, 5 and 7 "
	"Direct parameters of the root object are not accessible, "
	"only parameters of its children.")
	return parser

	def build(options):
	m5.ticks.fixGlobalFrequency()

	kernel_cmd = [
	"earlyprintk=pl011,0x1c090000",
	"console=ttyAMA0",
	"lpj=19988480",
	"norandmaps",
	"loglevel=8",
	"mem=%s" % default_mem_size,
	"root=/dev/vda1",
	"rw",
	"init=%s" % options.kernel_init,
	"vmalloc=768MB",
	]

	root = Root(full_system=True)

	disks = [default_disk] if len(options.disk) == 0 else options.disk
	system = createSystem(options.caches,
	options.kernel,
	options.bootscript,
	disks=disks)

	root.system = system
	system.boot_osflags = " ".join(kernel_cmd)

	if options.big_cpus + options.little_cpus == 0:
	m5.util.panic("Empty CPU clusters")

	big_model, little_model = cpu_types[options.cpu_type]

	all_cpus = []
	# big cluster
	if options.big_cpus > 0:
	system.bigCluster = big_model(system, options.big_cpus,
	options.big_cpu_clock)
	system.mem_mode = system.bigCluster.memoryMode()
	all_cpus += system.bigCluster.cpus

	# little cluster
	if options.little_cpus > 0:
	system.littleCluster = little_model(system, options.little_cpus,
	options.little_cpu_clock)
	system.mem_mode = system.littleCluster.memoryMode()
	all_cpus += system.littleCluster.cpus

	# Figure out the memory mode
	if options.big_cpus > 0 and options.little_cpus > 0 and \
	system.littleCluster.memoryMode() != system.littleCluster.memoryMode():
	m5.util.panic("Memory mode missmatch among CPU clusters")


	# create caches
	system.addCaches(options.caches, options.last_cache_level)
	if not options.caches:
	if options.big_cpus > 0 and system.bigCluster.requireCaches():
	m5.util.panic("Big CPU model requires caches")
	if options.little_cpus > 0 and system.littleCluster.requireCaches():
	m5.util.panic("Little CPU model requires caches")

	# Create a KVM VM and do KVM-specific configuration
	if issubclass(big_model, KvmCluster):
	_build_kvm(system, all_cpus)

	# Linux device tree
	if options.dtb is not None:
	system.dtb_filename = SysPaths.binary(options.dtb)
	else:
	system.generateDtb(m5.options.outdir, 'system.dtb')

	return root

	def _build_kvm(system, cpus):
	system.kvm_vm = KvmVM()

	# Assign KVM CPUs to their own event queues / threads. This
	# has to be done after creating caches and other child objects
	# since these mustn't inherit the CPU event queue.
	if len(cpus) > 1:
	device_eq = 0
	first_cpu_eq = 1
	for idx, cpu in enumerate(cpus):
	# Child objects usually inherit the parent's event
	# queue. Override that and use the same event queue for
	# all devices.
	for obj in cpu.descendants():
	obj.eventq_index = device_eq
	cpu.eventq_index = first_cpu_eq + idx



	def instantiate(options, checkpoint_dir=None):
	# Setup the simulation quantum if we are running in PDES-mode
	# (e.g., when using KVM)
	root = Root.getInstance()
	if root and _using_pdes(root):
	m5.util.inform("Running in PDES mode with a %s simulation quantum.",
	options.sim_quantum)
	root.sim_quantum = _to_ticks(options.sim_quantum)

	# Get and load from the chkpt or simpoint checkpoint
	if options.restore_from:
	if checkpoint_dir and not os.path.isabs(options.restore_from):
	cpt = os.path.join(checkpoint_dir, options.restore_from)
	else:
	cpt = options.restore_from

	m5.util.inform("Restoring from checkpoint %s", cpt)
	m5.instantiate(cpt)
	else:
	m5.instantiate()


	def run(checkpoint_dir=m5.options.outdir):
	# start simulation (and drop checkpoints when requested)
	while True:
	event = m5.simulate()
	exit_msg = event.getCause()
	if exit_msg == "checkpoint":
	print("Dropping checkpoint at tick %d" % m5.curTick())
	cpt_dir = os.path.join(checkpoint_dir, "cpt.%d" % m5.curTick())
	m5.checkpoint(cpt_dir)
	print("Checkpoint done.")
	else:
	print(exit_msg, " @ ", m5.curTick())
	break

	sys.exit(event.getCode())


	def main():
	parser = argparse.ArgumentParser(
	description="Generic ARM big.LITTLE configuration")
	addOptions(parser)
	options = parser.parse_args()
	root = build(options)
	root.apply_config(options.param)
	instantiate(options)
	run()


	if __name__ == "__m5_main__":
	main()