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"""
This gem5 configuation script creates a simple board to run a POWER
"hello world" binary.

This is setup is the close to the simplest setup possible using the gem5
library. It does not contain any kind of caching, IO, or any non-essential
components.

Usage
-----

```
scons build/POWER/gem5.opt
./build/POWER/gem5.opt configs/example/gem5_library/power-hello.py
```
"""

from gem5.isas import ISA
from gem5.utils.requires import requires
from gem5.resources.resource import Resource
from gem5.components.memory import SingleChannelDDR4_2400
from gem5.components.processors.cpu_types import CPUTypes
from gem5.components.boards.simple_board import SimpleBoard
from gem5.components.cachehierarchies.classic.no_cache import NoCache
from gem5.components.processors.simple_processor import SimpleProcessor
from gem5.simulate.simulator import Simulator

# This check ensures the gem5 binary is compiled to the POWER ISA target.
# If not, an exception will be thrown.
requires(isa_required=ISA.POWER)

# In this setup we don't have a cache. `NoCache` can be used for such setups.
cache_hierarchy = NoCache()

# We use a single channel DDR4_2400 memory system
memory = SingleChannelDDR4_2400(size="32MB")

# We use a simple ATOMIC processor with one core.
processor = SimpleProcessor(
    cpu_type=CPUTypes.ATOMIC, isa=ISA.POWER, num_cores=1
)

# The gem5 library simple board which can be used to run simple SE-mode
# simulations.
board = SimpleBoard(
    clk_freq="3GHz",
    processor=processor,
    memory=memory,
    cache_hierarchy=cache_hierarchy,
)

board.set_se_binary_workload(Resource("power-hello"))

# Lastly we run the simulation.
simulator = Simulator(board=board)
simulator.run()

print(
    "Exiting @ tick {} because {}.".format(
        simulator.get_current_tick(),
        simulator.get_last_exit_event_cause(),
    )
)