# Copyright (c) 2023 The Regents of the University of California
# All rights reserved.
#
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# modification, are permitted provided that the following conditions are
# met: redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer;
# redistributions in binary form must reproduce the above copyright
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# neither the name of the copyright holders nor the names of its
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# this software without specific prior written permission.
#
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# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

"""

This script demonstrates how to use KVM CPU without perf.
This simulation boots Ubuntu 18.04 using 2 KVM CPUs without using perf.

Usage
-----

```
scons build/X86/gem5.opt -j`nproc`
./build/X86/gem5.opt configs/example/gem5_library/x86-ubuntu-run-with-kvm-no-perf.py
```
"""

from gem5.coherence_protocol import CoherenceProtocol
from gem5.components.boards.x86_board import X86Board
from gem5.components.cachehierarchies.ruby.mesi_two_level_cache_hierarchy import (
    MESITwoLevelCacheHierarchy,
)
from gem5.components.memory.single_channel import SingleChannelDDR4_2400
from gem5.components.processors.cpu_types import CPUTypes
from gem5.components.processors.simple_switchable_processor import (
    SimpleSwitchableProcessor,
)
from gem5.isas import ISA
from gem5.resources.resource import obtain_resource
from gem5.simulate.exit_event import ExitEvent
from gem5.simulate.simulator import Simulator
from gem5.utils.requires import requires

# This simulation requires using KVM with gem5 compiled for X86 simulation
# and with MESI_Two_Level cache coherence protocol.
requires(
    isa_required=ISA.X86,
    coherence_protocol_required=CoherenceProtocol.MESI_TWO_LEVEL,
    kvm_required=True,
)

from gem5.components.cachehierarchies.ruby.mesi_two_level_cache_hierarchy import (
    MESITwoLevelCacheHierarchy,
)

cache_hierarchy = MESITwoLevelCacheHierarchy(
    l1d_size="32KiB",
    l1d_assoc=8,
    l1i_size="32KiB",
    l1i_assoc=8,
    l2_size="512KiB",
    l2_assoc=16,
    num_l2_banks=1,
)

# Main memory
memory = SingleChannelDDR4_2400(size="3GiB")

# This is a switchable CPU. We first boot Ubuntu using KVM, then the guest
# will exit the simulation by calling "m5 exit" (see the `command` variable
# below, which contains the command to be run in the guest after booting).
# Upon exiting from the simulation, the Exit Event handler will switch the
# CPU type (see the ExitEvent.EXIT line below, which contains a map to
# a function to be called when an exit event happens).
processor = SimpleSwitchableProcessor(
    starting_core_type=CPUTypes.KVM,
    switch_core_type=CPUTypes.TIMING,
    isa=ISA.X86,
    num_cores=2,
)

# Here we tell the KVM CPU (the starting CPU) not to use perf.
for proc in processor.start:
    proc.core.usePerf = False

# Here we setup the board. The X86Board allows for Full-System X86 simulations.
board = X86Board(
    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 X86Board takes a kernel, a
# disk image, and, optionally, a command to run.

# This is the command to run after the system has booted. The first `m5 exit`
# will stop the simulation so we can switch the CPU cores from KVM to timing
# and continue the simulation to run the echo command, sleep for a second,
# then, again, call `m5 exit` to terminate the simulation. After simulation
# has ended you may inspect `m5out/system.pc.com_1.device` to see the echo
# output.
command = (
    "m5 exit;"
    + "echo 'This is running on Timing CPU cores.';"
    + "sleep 1;"
    + "m5 exit;"
)

workload = obtain_resource("x86-ubuntu-18.04-boot")
workload.set_parameter("readfile_contents", command)
board.set_workload(workload)

simulator = Simulator(
    board=board,
    on_exit_event={
        # Here we want override the default behavior for the first m5 exit
        # exit event. Instead of exiting the simulator, we just want to
        # switch the processor. The 2nd m5 exit after will revert to using
        # default behavior where the simulator run will exit.
        ExitEvent.EXIT: (func() for func in [processor.switch])
    },
)
simulator.run()