# Copyright (c) 2021 The Regents of the University of California
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"""
This script shows an example of running a full system RISCV Ubuntu boot
simulation using the gem5 library. This simulation boots Ubuntu 20.04 using
2 TIMING CPU cores. The simulation ends when the startup is completed
successfully.

Usage
-----

```
scons build/RISCV/gem5.opt
./build/RISCV/gem5.opt \
    configs/example/gem5_library/riscv-ubuntu-run.py
```
"""

import m5
from m5.objects import Root

from gem5.utils.requires import requires
from gem5.components.boards.riscv_board import RiscvBoard
from gem5.components.memory import DualChannelDDR4_2400
from gem5.components.processors.simple_processor import (
    SimpleProcessor,
)
from gem5.components.processors.cpu_types import CPUTypes
from gem5.isas import ISA
from gem5.coherence_protocol import CoherenceProtocol
from gem5.resources.resource import Resource

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

requires(
    isa_required=ISA.RISCV,
)

# With RISCV, 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 = "3GB")

# Here we setup the processor. We use a simple processor.
processor = SimpleProcessor(
    cpu_type=CPUTypes.TIMING,
    num_cores=2,
)

# Here we setup the board. The RiscvBoard allows for Full-System RISCV
# simulations.
board = RiscvBoard(
    clk_freq="3GHz",
    processor=processor,
    memory=memory,
    cache_hierarchy=cache_hierarchy,
)

# Here we set the Full System workload.

# The `set_kernel_disk_workload` function for the RiscvBoard accepts a
# RISCV bootloader and a disk image. 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/system.pc.com_1.device`
# to see the stdout.

board.set_kernel_disk_workload(
    # The RISCV bootloader will be automatically downloaded to the
    # `~/.cache/gem5` directory if not already present.
    # The riscv-ubuntu boot-test was tested with riscv-bootloader-5.10
    kernel=Resource(
        "riscv-bootloader-vmlinux-5.10",
    ),
    # The RISCV ubuntu image will be automatically downloaded to the
    # `~/.cache/gem5` directory if not already present.
    disk_image=Resource(
        "riscv-ubuntu-20.04-img",
    ),
)

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

m5.instantiate()

# We simulate the system till we encounter `m5_exit instruction encountered`.

exit_event = m5.simulate()

# We check whether the simulation ended with `m5_exit instruction encountered`

if exit_event.getCause() == "m5_exit instruction encountered":
    # We acknowledge the user that the boot was successful.

    print("Successfully completed booting!")
else:
    # `m5_exit instruction encountered` was never encountered. We exit the
    # program unsuccessfully.

    print("The startup was not completed successfully!",)
    print(
    "Exiting @ tick {} because {}."\
        .format(m5.curTick(), exit_event.getCause())
    )
    exit(-1)

# We are done with the simulation. We exit the program now.

print(
"Exiting @ tick {} because {}."\
    .format(m5.curTick(), exit_event.getCause())
)