configs,stdlib,tests: Update riscvmatched-fs.py to-init

The "test-gem5-library-example-riscvmatched-fs" test, which runs
"configs/example/gem5_library/riscvmatched-fs.py", was running the
script in full. This takes a very long time. Given we already have boot
tests for RISCV, it's better to just run this configuration to just the
end of the Linux boot (significantly faster than a full OS boot). This
patch adds this feature to the config script and modifies the test to
utilize it.

Change-Id: I1e37a26aab5e9a127ebd64590be79fbc16fe53aa
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/65853
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>

configs/example/gem5_library/riscvmatched-fs.py

@@ -44,8 +44,23 @@ from gem5.isas import ISA
 from gem5.simulate.simulator import Simulator
 from gem5.resources.workload import Workload
 
+import argparse
+
 requires(isa_required=ISA.RISCV)
 
+parser = argparse.ArgumentParser(
+    description="A script which uses the RISCVMatchedBoard in FS mode."
+)
+
+parser.add_argument(
+    "-i",
+    "--to-init",
+    action="store_true",
+    help="Exit the simulation after the Linux Kernel boot.",
+)
+
+args = parser.parse_args()
+
 # instantiate the riscv matched board with default parameters
 board = RISCVMatchedBoard(
     clk_freq="1.2GHz",
@@ -57,7 +72,16 @@ board = RISCVMatchedBoard(
 # Ubuntu 20.04. Once the system successfully boots it encounters an `m5_exit`
 # instruction which stops the simulation. When the simulation has ended you may
 # inspect `m5out/system.pc.com_1.device` to see the stdout.
-board.set_workload(Workload("riscv-ubuntu-20.04-boot"))
+#
+# In the case where the `-i` flag is passed, we add the kernel argument
+# `init=/root/exit.sh`. This means the simulation will exit after the Linux
+# Kernel has booted.
+workload = Workload("riscv-ubuntu-20.04-boot")
+kernel_args = board.get_default_kernel_args()
+if args.to_init:
+    kernel_args.append("init=/root/exit.sh")
+workload.set_parameter("kernel_args", kernel_args)
+board.set_workload(workload)
 
 simulator = Simulator(board=board)
 simulator.run()