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"""This script is the full system example script from the ARM
Research Starter Kit on System Modeling. More information can be found
at: http://www.arm.com/ResearchEnablement/SystemModeling
"""

import os
import m5
from m5.util import addToPath
from m5.objects import *
from m5.options import *
import argparse

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

from common import SysPaths
from common import ObjectList
from common import MemConfig
from common.cores.arm import O3_ARM_v7a, HPI

import devices


default_kernel = "vmlinux.arm64"
default_disk = "linaro-minimal-aarch64.img"
default_root_device = "/dev/vda1"


# Pre-defined CPU configurations. Each tuple must be ordered as : (cpu_class,
# l1_icache_class, l1_dcache_class, l2_Cache_class). Any of
# the cache class may be 'None' if the particular cache is not present.
cpu_types = {
    "atomic": (AtomicSimpleCPU, None, None, None),
    "minor": (MinorCPU, devices.L1I, devices.L1D, devices.L2),
    "hpi": (HPI.HPI, HPI.HPI_ICache, HPI.HPI_DCache, HPI.HPI_L2),
    "o3": (
        O3_ARM_v7a.O3_ARM_v7a_3,
        O3_ARM_v7a.O3_ARM_v7a_ICache,
        O3_ARM_v7a.O3_ARM_v7a_DCache,
        O3_ARM_v7a.O3_ARM_v7aL2,
    ),
}


def create_cow_image(name):
    """Helper function to create a Copy-on-Write disk image"""
    image = CowDiskImage()
    image.child.image_file = SysPaths.disk(name)

    return image


def create(args):
    """Create and configure the system object."""

    if args.script and not os.path.isfile(args.script):
        print(f"Error: Bootscript {args.script} does not exist")
        sys.exit(1)

    cpu_class = cpu_types[args.cpu][0]
    mem_mode = cpu_class.memory_mode()
    # Only simulate caches when using a timing CPU (e.g., the HPI model)
    want_caches = True if mem_mode == "timing" else False

    system = devices.SimpleSystem(
        want_caches,
        args.mem_size,
        mem_mode=mem_mode,
        workload=ArmFsLinux(object_file=SysPaths.binary(args.kernel)),
        readfile=args.script,
    )

    MemConfig.config_mem(args, system)

    # Add the PCI devices we need for this system. The base system
    # doesn't have any PCI devices by default since they are assumed
    # to be added by the configuration scripts needing them.
    system.pci_devices = [
        # Create a VirtIO block device for the system's boot
        # disk. Attach the disk image using gem5's Copy-on-Write
        # functionality to avoid writing changes to the stored copy of
        # the disk image.
        PciVirtIO(vio=VirtIOBlock(image=create_cow_image(args.disk_image)))
    ]

    # Attach the PCI devices to the system. The helper method in the
    # system assigns a unique PCI bus ID to each of the devices and
    # connects them to the IO bus.
    for dev in system.pci_devices:
        system.attach_pci(dev)

    # Wire up the system's memory system
    system.connect()

    # Add CPU clusters to the system
    system.cpu_cluster = [
        devices.ArmCpuCluster(
            system,
            args.num_cores,
            args.cpu_freq,
            "1.0V",
            *cpu_types[args.cpu],
            tarmac_gen=args.tarmac_gen,
            tarmac_dest=args.tarmac_dest,
        )
    ]

    # Create a cache hierarchy for the cluster. We are assuming that
    # clusters have core-private L1 caches and an L2 that's shared
    # within the cluster.
    system.addCaches(want_caches, last_cache_level=2)

    # Setup gem5's minimal Linux boot loader.
    system.realview.setupBootLoader(system, SysPaths.binary)

    if args.dtb:
        system.workload.dtb_filename = args.dtb
    else:
        # No DTB specified: autogenerate DTB
        system.workload.dtb_filename = os.path.join(
            m5.options.outdir, "system.dtb"
        )
        system.generateDtb(system.workload.dtb_filename)

    if args.initrd:
        system.workload.initrd_filename = args.initrd

    # Linux boot command flags
    kernel_cmd = [
        # Tell Linux to use the simulated serial port as a console
        "console=ttyAMA0",
        # Hard-code timi
        "lpj=19988480",
        # Disable address space randomisation to get a consistent
        # memory layout.
        "norandmaps",
        # Tell Linux where to find the root disk image.
        f"root={args.root_device}",
        # Mount the root disk read-write by default.
        "rw",
        # Tell Linux about the amount of physical memory present.
        f"mem={args.mem_size}",
    ]
    system.workload.command_line = " ".join(kernel_cmd)

    if args.with_pmu:
        for cluster in system.cpu_cluster:
            interrupt_numbers = [args.pmu_ppi_number] * len(cluster)
            cluster.addPMUs(interrupt_numbers)

    return system


def run(args):
    cptdir = m5.options.outdir
    if args.checkpoint:
        print(f"Checkpoint directory: {cptdir}")

    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(m5.options.outdir, "cpt.%d" % m5.curTick())
            m5.checkpoint(os.path.join(cpt_dir))
            print("Checkpoint done.")
        else:
            print(f"{exit_msg} ({event.getCode()}) @ {m5.curTick()}")
            break


def arm_ppi_arg(int_num: int) -> int:
    """Argparse argument parser for valid Arm PPI numbers."""
    # PPIs (1056 <= int_num <= 1119) are not yet supported by gem5
    int_num = int(int_num)
    if 16 <= int_num <= 31:
        return int_num
    raise ValueError(f"{int_num} is not a valid Arm PPI number")


def main():
    parser = argparse.ArgumentParser(epilog=__doc__)

    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(
        "--initrd",
        type=str,
        default=None,
        help="initrd/initramfs file to load",
    )
    parser.add_argument(
        "--disk-image",
        type=str,
        default=default_disk,
        help="Disk to instantiate",
    )
    parser.add_argument(
        "--root-device",
        type=str,
        default=default_root_device,
        help=f"OS device name for root partition (default: {default_root_device})",
    )
    parser.add_argument(
        "--script", type=str, default="", help="Linux bootscript"
    )
    parser.add_argument(
        "--cpu",
        type=str,
        choices=list(cpu_types.keys()),
        default="atomic",
        help="CPU model to use",
    )
    parser.add_argument("--cpu-freq", type=str, default="4GHz")
    parser.add_argument(
        "--num-cores", type=int, default=1, help="Number of CPU cores"
    )
    parser.add_argument(
        "--mem-type",
        default="DDR3_1600_8x8",
        choices=ObjectList.mem_list.get_names(),
        help="type of memory to use",
    )
    parser.add_argument(
        "--mem-channels", type=int, default=1, help="number of memory channels"
    )
    parser.add_argument(
        "--mem-ranks",
        type=int,
        default=None,
        help="number of memory ranks per channel",
    )
    parser.add_argument(
        "--mem-size",
        action="store",
        type=str,
        default="2GB",
        help="Specify the physical memory size",
    )
    parser.add_argument(
        "--tarmac-gen",
        action="store_true",
        help="Write a Tarmac trace.",
    )
    parser.add_argument(
        "--tarmac-dest",
        choices=TarmacDump.vals,
        default="stdoutput",
        help="Destination for the Tarmac trace output. [Default: stdoutput]",
    )
    parser.add_argument(
        "--with-pmu",
        action="store_true",
        help="Add a PMU to each core in the cluster.",
    )
    parser.add_argument(
        "--pmu-ppi-number",
        type=arm_ppi_arg,
        default=23,
        help="The number of the PPI to use to connect each PMU to its core. "
        "Must be an integer and a valid PPI number (16 <= int_num <= 31).",
    )
    parser.add_argument("--checkpoint", action="store_true")
    parser.add_argument("--restore", type=str, default=None)

    args = parser.parse_args()

    root = Root(full_system=True)
    root.system = create(args)

    if args.restore is not None:
        m5.instantiate(args.restore)
    else:
        m5.instantiate()

    run(args)


if __name__ == "__m5_main__":
    main()