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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 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, walk_cache_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, None),
    "minor" : (MinorCPU,
               devices.L1I, devices.L1D,
               devices.WalkCache,
               devices.L2),
    "hpi" : ( HPI.HPI,
              HPI.HPI_ICache, HPI.HPI_DCache,
              HPI.HPI_WalkCache,
              HPI.HPI_L2)
}

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("Error: Bootscript %s does not exist" % args.script)
        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.CpuCluster(system,
                           args.num_cores,
                           args.cpu_freq, "1.0V",
                           *cpu_types[args.cpu]),
    ]

    # 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)

    # 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.
        "root=%s" % args.root_device,
        # Mount the root disk read-write by default.
        "rw",
        # Tell Linux about the amount of physical memory present.
        "mem=%s" % args.mem_size,
    ]
    system.workload.command_line = " ".join(kernel_cmd)

    return system


def run(args):
    cptdir = m5.options.outdir
    if args.checkpoint:
        print("Checkpoint directory: %s" % 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(exit_msg, " @ ", m5.curTick())
            break

    sys.exit(event.getCode())


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("--disk-image", type=str,
                        default=default_disk,
                        help="Disk to instantiate")
    parser.add_argument("--root-device", type=str,
                        default=default_root_device,
                        help="OS device name for root partition (default: {})"
                             .format(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("--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()
