# Copyright (c) 2021 The Univerity of Texas at Austin
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"""
This script boots with KVM then switches processors and exits.
"""

import argparse

import m5
from m5.objects import Root

from gem5.isas import ISA
from gem5.components.boards.x86_board import X86Board
from gem5.coherence_protocol import CoherenceProtocol
from gem5.components.memory import SingleChannelDDR3_1600
from gem5.components.processors.cpu_types import CPUTypes
from gem5.components.processors.simple_switchable_processor import (
    SimpleSwitchableProcessor,
)
from gem5.resources.resource import Resource
from gem5.runtime import (
    get_runtime_coherence_protocol, get_runtime_isa
)
from gem5.utils.requires import requires

parser = argparse.ArgumentParser(
    description="A script to test switching cpus. This test boots"
    "the linux kernel with the KVM cpu, then switches cpus until exiting."
)
parser.add_argument(
    "-m",
    "--mem-system",
    type=str,
    choices=("classic", "mi_example", "mesi_two_level"),
    required=True,
    help="The memory system.",
)
parser.add_argument(
    "-n",
    "--num-cpus",
    type=int,
    choices=(1, 2, 4, 8),
    required=True,
    help="The number of CPUs.",
)
parser.add_argument(
    "-c",
    "--cpu",
    type=str,
    choices=("kvm", "atomic", "timing", "o3"),
    required=True,
    help="The CPU type.",
)
parser.add_argument(
    "-r",
    "--resource-directory",
    type=str,
    required=False,
    help="The directory in which resources will be downloaded or exist.",
)
parser.add_argument(
    "-k",
    "--kernel-args",
    type=str,
    default="init=/root/gem5_init.sh",
    help="Additional kernel boot arguments.",
)

args = parser.parse_args()

coherence_protocol_required = None
if args.mem_system == "mi_example":
    coherence_protocol_required = CoherenceProtocol.MI_EXAMPLE
elif args.mem_system == "mesi_two_level":
    coherence_protocol_required = CoherenceProtocol.MESI_TWO_LEVEL

requires(
    isa_required=ISA.X86,
    coherence_protocol_required=coherence_protocol_required,
    kvm_required=(args.cpu == "kvm"),
)

cache_hierarchy = None
if args.mem_system == "mi_example":
    from gem5.components.cachehierarchies.ruby.\
        mi_example_cache_hierarchy import (
        MIExampleCacheHierarchy,
    )

    cache_hierarchy = MIExampleCacheHierarchy(size="32kB", assoc=8)
elif args.mem_system == "mesi_two_level":
    from gem5.components.cachehierarchies.ruby.\
        mesi_two_level_cache_hierarchy import (
        MESITwoLevelCacheHierarchy,
    )

    cache_hierarchy = MESITwoLevelCacheHierarchy(
        l1d_size="16kB",
        l1d_assoc=8,
        l1i_size="16kB",
        l1i_assoc=8,
        l2_size="256kB",
        l2_assoc=16,
        num_l2_banks=1,
    )
elif args.mem_system == "classic":
    from gem5.components.cachehierarchies.classic.\
        private_l1_cache_hierarchy import (
        PrivateL1CacheHierarchy,
    )

    cache_hierarchy = PrivateL1CacheHierarchy(l1d_size="16kB", l1i_size="16kB")
else:
    raise NotImplementedError(
        "Memory system '{}' is not supported in the boot tests.".format(
            args.mem_system
        )
    )

assert cache_hierarchy != None

# Setup the system memory.
memory = SingleChannelDDR3_1600(size="3GB")

# Setup a Processor.
cpu_type = None
if args.cpu == "kvm":
    cpu_type = CPUTypes.KVM
elif args.cpu == "atomic":
    cpu_type = CPUTypes.ATOMIC
elif args.cpu == "timing":
    cpu_type = CPUTypes.TIMING
elif args.cpu == "o3":
    cpu_type = CPUTypes.O3
else:
    raise NotImplementedError(
        "CPU type '{}' is not supported in the boot tests.".format(args.cpu)
    )

assert cpu_type != None

processor = SimpleSwitchableProcessor(
    starting_core_type=CPUTypes.KVM,
    switch_core_type=cpu_type,
    num_cores=args.num_cpus,
)

# Setup the motherboard.
motherboard = X86Board(
    clk_freq="3GHz",
    processor=processor,
    memory=memory,
    cache_hierarchy=cache_hierarchy,
)

kernal_args = motherboard.get_default_kernel_args() + [args.kernel_args]

# Set the Full System workload.
motherboard.set_kernel_disk_workload(
    kernel=Resource(
        "x86-linux-kernel-5.4.49",
        resource_directory=args.resource_directory,
    ),
    disk_image=Resource(
        "x86-ubuntu-img",
        resource_directory=args.resource_directory,
    ),
    # The first exit signals to switch processors.
    readfile_contents="m5 exit\nm5 exit\n",
    kernel_args=kernal_args,
)


# Begin running of the simulation. This will exit once the Linux system boot
# is complete.
print("Running with ISA: " + get_runtime_isa().name)
print("Running with protocol: " + get_runtime_coherence_protocol().name)
print()

root = Root(full_system=True, system=motherboard)

root.sim_quantum = int(1e9)

m5.instantiate()

print("Booting!")
exit_event = m5.simulate()
if exit_event.getCause() != "m5_exit instruction encountered":
    raise Exception("Expected exit instruction after boot!")

print(f"Switching processors to {args.cpu}!")
processor.switch()

exit_event = m5.simulate()
exit_cause = exit_event.getCause()

if exit_cause != "m5_exit instruction encountered":
    raise Exception(
        f"Expected exit after switching processors, received: {exit_cause}"
    )
print("Exiting @ tick {} because {}.".format(m5.curTick(), exit_cause))