# Copyright (c) 2022 The Regents of the University of California
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"""
This script shows an example of booting an ARM based full system Ubuntu
disk image using the gem5's standard library. This simulation boots the disk
image using 2 TIMING CPU cores. The simulation ends when the startup is
completed successfully (i.e. when an `m5_exit instruction is reached on
successful boot).

Usage
-----

```
scons build/ARM/gem5.opt -j<NUM_CPUS>
./build/ARM/gem5.opt configs/example/gem5_library/arm-ubuntu-boot-exit.py
```

"""

import os
from gem5.isas import ISA
from m5.objects import ArmDefaultRelease
from gem5.utils.requires import requires
from gem5.resources.resource import Resource
from gem5.simulate.simulator import Simulator
from m5.objects import VExpress_GEM5_Foundation
from gem5.components.boards.arm_board import ArmBoard
from gem5.components.memory import DualChannelDDR4_2400
from gem5.components.processors.cpu_types import CPUTypes
from gem5.resources.resource import CustomDiskImageResource
from gem5.components.processors.simple_processor import SimpleProcessor

# This runs a check to ensure the gem5 binary is compiled for ARM.

requires(
    isa_required=ISA.ARM,
)

# With ARM, we use simple caches.

from gem5.components.cachehierarchies.classic\
    .private_l1_private_l2_cache_hierarchy import (
    PrivateL1PrivateL2CacheHierarchy,
)


# Here we setup the parameters of the l1 and l2 caches.

cache_hierarchy = PrivateL1PrivateL2CacheHierarchy(
    l1d_size="16kB",
    l1i_size="16kB",
    l2_size="256kB",
)

# Memory: Dual Channel DDR4 2400 DRAM device.

memory = DualChannelDDR4_2400(size = "2GB")

# Here we setup the processor. We use a simple TIMING processor. The config
# script was also tested with ATOMIC processor.

processor = SimpleProcessor(
    cpu_type=CPUTypes.TIMING,
    num_cores=2,
)

# The ArmBoard requires a `release` to be specified. This adds all the
# extensions or features to the system. We are setting this to Armv8
# (ArmDefaultRelease) in this example config script.

release = ArmDefaultRelease()

# The platform sets up the memory ranges of all the on-chip and off-chip
# devices present on the ARM system.

platform = VExpress_GEM5_Foundation()

# Here we setup the board. The ArmBoard allows for Full-System ARM simulations.

board = ArmBoard(
    clk_freq = "3GHz",
    processor = processor,
    memory = memory,
    cache_hierarchy = cache_hierarchy,
    release = release,
    platform = platform
)

# Here we set the Full System workload.

# The `set_kernel_disk_workload` function on the ArmBoard accepts an ARM
# kernel, a disk image, and, path to the bootloader.

board.set_kernel_disk_workload(

    # The ARM kernel will be automatically downloaded to the `~/.cache/gem5`
    # directory if not already present. The arm-ubuntu-boot-exit was tested
    # with `vmlinux.arm64`

    kernel = Resource("arm64-linux-kernel-5.4.49"),

    # The ARM ubuntu image will be automatically downloaded to the
    # `~/.cache/gem5` directory if not already present.

    disk_image = Resource("arm64-ubuntu-18.04-img"),

    # We need to specify the path for the bootloader file `boot.arm64`.

    bootloader = Resource("arm64-bootloader"),

    # For the arm64-ubuntu-18.04.img, we need to specify the readfile content

    readfile_contents = "m5 exit"
)

# We define the system with the aforementioned system defined.

simulator = Simulator(board = board)

# Once the system successfully boots, it encounters an
# `m5_exit instruction encountered`. We stop the simulation then. When the
# simulation has ended you may inspect `m5out/board.terminal` to see
# the stdout.

simulator.run()