stdlib: Removed SECURITY from the ArmBoard Script

The ARM Board does not support SECURITY extension at the moment.
This change removes the extension from the config script so that
the board functions properly.

Change-Id: I12a5bdf48803e86739967830204a9eef6057bd36
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/60209
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

configs/example/gem5_library/arm-ubuntu-boot-exit.py

@@ -41,7 +41,6 @@ scons build/ARM/gem5.opt -j<NUM_CPUS>
 
 """
 
-import os
 from gem5.isas import ISA
 from m5.objects import ArmDefaultRelease
 from gem5.utils.requires import requires
@@ -51,7 +50,6 @@ 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.
@@ -90,10 +88,15 @@ processor = SimpleProcessor(
 
 # 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.
+# (ArmDefaultRelease) in this example config script. However, the ArmBoard
+# currently does not support SECURITY extension.
 
 release = ArmDefaultRelease()
 
+# Removing the SECURITY extension.
+
+release.extensions.remove(release.extensions[2])
+
 # The platform sets up the memory ranges of all the on-chip and off-chip
 # devices present on the ARM system.
 
@@ -128,9 +131,9 @@ board.set_kernel_disk_workload(
 
     disk_image = Resource("arm64-ubuntu-18.04-img"),
 
-    # We need to specify the path for the bootloader file `boot.arm64`.
+    # We need to specify the path for the bootloader file.
 
-    bootloader = Resource("arm64-bootloader"),
+    bootloader = Resource("arm64-bootloader-foundation"),
 
     # For the arm64-ubuntu-18.04.img, we need to specify the readfile content
 

src/python/gem5/components/boards/arm_board.py

@@ -75,6 +75,7 @@ class ArmBoard(ArmSystem, AbstractBoard, KernelDiskWorkload):
     **Limitations**
     * The board currently does not support ruby caches.
     * stage2 walker ports are ignored.
+    * This version does not support SECURITY extension.
     """
     __metaclass__ = ABCMeta