sim,configs: Default m5ops_base to 0 (disabled) on x86.

This is already the default for other platforms. This is most important
when using KVM, where this mechanism is the only way to trigger pseudo
instructions, or in SE mode to also trigger system calls.

Change-Id: I0094e6814898ba397c7425e0fe76d84853bb17ad
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/52498
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

configs/common/FSConfig.py

@@ -445,6 +445,8 @@ def connectX86RubySystem(x86_sys):
 def makeX86System(mem_mode, numCPUs=1, mdesc=None, workload=None, Ruby=False):
     self = System()
 
+    self.m5ops_base = 0xffff0000
+
     if workload is None:
         workload = X86FsWorkload()
     self.workload = workload

configs/example/apu_se.py

@@ -544,6 +544,7 @@ if fast_forward:
     have_kvm_support = 'BaseKvmCPU' in globals()
     if have_kvm_support and buildEnv['TARGET_ISA'] == "x86":
         system.vm = KvmVM()
+        system.m5ops_base = 0xffff0000
         for i in range(len(host_cpu.workload)):
             host_cpu.workload[i].useArchPT = True
             host_cpu.workload[i].kvmInSE = True

configs/example/se.py

@@ -200,6 +200,7 @@ for cpu in system.cpu:
 if ObjectList.is_kvm_cpu(CPUClass) or ObjectList.is_kvm_cpu(FutureClass):
     if buildEnv['TARGET_ISA'] == 'x86':
         system.kvm_vm = KvmVM()
+        system.m5ops_base = 0xffff0000
         for process in multiprocesses:
             process.useArchPT = True
             process.kvmInSE = True

src/python/gem5/components/boards/x86_board.py

@@ -99,6 +99,8 @@ class X86Board(AbstractBoard, KernelDiskWorkload):
         # Set up all of the I/O.
         self._setup_io_devices()
 
+        self.m5ops_base = 0xffff0000
+
     def _setup_io_devices(self):
         """ Sets up the x86 IO devices.
 

src/sim/System.py

@@ -124,10 +124,8 @@ class System(SimObject):
 
     # SE mode doesn't use the ISA System subclasses, and so we need to set an
     # ISA specific value in this class directly.
-    m5ops_base = Param.Addr(
-        0xffff0000 if buildEnv['TARGET_ISA'] == 'x86' else 0,
-        "Base of the 64KiB PA range used for memory-mapped m5ops. Set to 0 "
-        "to disable.")
+    m5ops_base = Param.Addr(0, "Base of the 64KiB PA range used for "
+       "memory-mapped m5ops. Set to 0 to disable.")
 
     if buildEnv['USE_KVM']:
         kvm_vm = Param.KvmVM(NULL, 'KVM VM (i.e., shared memory domain)')