tests: Add CPU switching tests

This changeset adds a set of tests that stress the CPU switching
code. It adds the following test configurations:

 * tsunami-switcheroo-full -- Alpha system (atomic, timing, O3)
 * realview-switcheroo-atomic -- ARM system (atomic<->atomic)
 * realview-switcheroo-timing -- ARM system (timing<->timing)
 * realview-switcheroo-o3 -- ARM system (O3<->O3)
 * realview-switcheroo-full -- ARM system (atomic, timing, O3)

Reference data is provided for the 10.linux-boot test case. All of the
tests trigger a CPU switch once per millisecond during the boot
process.

The in-order CPU model was not included in any of the tests as it does
not support CPU handover.

9 files changed, 413 insertions, 4 deletions

diff --git a/tests/configs/alpha_generic.py b/tests/configs/alpha_generic.py
index 429f4faba..a4ebba54d 100644
--- a/tests/configs/alpha_generic.py
+++ b/tests/configs/alpha_generic.py
@@ -91,3 +91,10 @@ class LinuxAlphaFSSystemUniprocessor(LinuxAlphaSystemBuilder,
     def __init__(self, **kwargs):
         BaseFSSystemUniprocessor.__init__(self, **kwargs)
         LinuxAlphaSystemBuilder.__init__(self)
+
+class LinuxAlphaFSSwitcheroo(LinuxAlphaSystemBuilder, BaseFSSwitcheroo):
+    """Uniprocessor Alpha system prepared for CPU switching"""
+
+    def __init__(self, **kwargs):
+        BaseFSSwitcheroo.__init__(self, **kwargs)
+        LinuxAlphaSystemBuilder.__init__(self)
diff --git a/tests/configs/arm_generic.py b/tests/configs/arm_generic.py
index 07251f2d6..95f9b8bd1 100644
--- a/tests/configs/arm_generic.py
+++ b/tests/configs/arm_generic.py
@@ -93,3 +93,11 @@ class LinuxArmFSSystemUniprocessor(LinuxArmSystemBuilder,
     def __init__(self, machine_type='RealView_PBX', **kwargs):
         BaseFSSystemUniprocessor.__init__(self, **kwargs)
         LinuxArmSystemBuilder.__init__(self, machine_type)
+
+
+class LinuxArmFSSwitcheroo(LinuxArmSystemBuilder, BaseFSSwitcheroo):
+    """Uniprocessor ARM system prepared for CPU switching"""
+
+    def __init__(self, machine_type='RealView_PBX', **kwargs):
+        BaseFSSwitcheroo.__init__(self, **kwargs)
+        LinuxArmSystemBuilder.__init__(self, machine_type)
diff --git a/tests/configs/base_config.py b/tests/configs/base_config.py
index 945bcb495..370b76c46 100644
--- a/tests/configs/base_config.py
+++ b/tests/configs/base_config.py
@@ -121,10 +121,13 @@ class BaseSystem(object):
 
         sha_bus = self.create_caches_shared(system)
         for cpu in system.cpu:
-            self.create_caches_private(cpu)
-            self.init_cpu(system, cpu)
-            cpu.connectAllPorts(sha_bus if sha_bus != None else system.membus,
-                                system.membus)
+            if not cpu.switched_out:
+                self.create_caches_private(cpu)
+                self.init_cpu(system, cpu)
+                cpu.connectAllPorts(sha_bus if sha_bus != None else system.membus,
+                                    system.membus)
+            else:
+                self.init_cpu(system, cpu)
 
     @abstractmethod
     def create_system(self):
@@ -173,3 +176,16 @@ class BaseFSSystemUniprocessor(BaseFSSystem):
 
     def create_caches_shared(self, system):
         return None
+
+class BaseFSSwitcheroo(BaseFSSystem):
+    """Uniprocessor system prepared for CPU switching"""
+
+    def __init__(self, cpu_classes, **kwargs):
+        BaseFSSystem.__init__(self, **kwargs)
+        self.cpu_classes = tuple(cpu_classes)
+
+    def create_cpus(self):
+        cpus = [ cclass(cpu_id=0, clock='2GHz', switched_out=True)
+                 for cclass in self.cpu_classes ]
+        cpus[0].switched_out = False
+        return cpus
diff --git a/tests/configs/realview-switcheroo-atomic.py b/tests/configs/realview-switcheroo-atomic.py
new file mode 100644
index 000000000..880162527
--- /dev/null
+++ b/tests/configs/realview-switcheroo-atomic.py
@@ -0,0 +1,48 @@
+# Copyright (c) 2012 ARM Limited
+# All rights reserved.
+#
+# The license below extends only to copyright in the software and shall
+# not be construed as granting a license to any other intellectual
+# property including but not limited to intellectual property relating
+# to a hardware implementation of the functionality of the software
+# licensed hereunder.  You may use the software subject to the license
+# terms below provided that you ensure that this notice is replicated
+# unmodified and in its entirety in all distributions of the software,
+# modified or unmodified, in source code or in binary form.
+#
+# Redistribution and use in source and binary forms, with or without
+# 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
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution;
+# neither the name of the copyright holders nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# Authors: Andreas Sandberg
+
+from m5.objects import *
+from arm_generic import *
+import switcheroo
+
+root = LinuxArmFSSwitcheroo(
+    cpu_classes=(AtomicSimpleCPU, AtomicSimpleCPU)
+    ).create_root()
+
+# Setup a custom test method that uses the switcheroo tester that
+# switches between CPU models.
+run_test = switcheroo.run_test
diff --git a/tests/configs/realview-switcheroo-full.py b/tests/configs/realview-switcheroo-full.py
new file mode 100644
index 000000000..091357114
--- /dev/null
+++ b/tests/configs/realview-switcheroo-full.py
@@ -0,0 +1,48 @@
+# Copyright (c) 2012 ARM Limited
+# All rights reserved.
+#
+# The license below extends only to copyright in the software and shall
+# not be construed as granting a license to any other intellectual
+# property including but not limited to intellectual property relating
+# to a hardware implementation of the functionality of the software
+# licensed hereunder.  You may use the software subject to the license
+# terms below provided that you ensure that this notice is replicated
+# unmodified and in its entirety in all distributions of the software,
+# modified or unmodified, in source code or in binary form.
+#
+# Redistribution and use in source and binary forms, with or without
+# 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
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution;
+# neither the name of the copyright holders nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# Authors: Andreas Sandberg
+
+from m5.objects import *
+from arm_generic import *
+import switcheroo
+
+root = LinuxArmFSSwitcheroo(
+    cpu_classes=(AtomicSimpleCPU, TimingSimpleCPU, DerivO3CPU)
+    ).create_root()
+
+# Setup a custom test method that uses the switcheroo tester that
+# switches between CPU models.
+run_test = switcheroo.run_test
diff --git a/tests/configs/realview-switcheroo-o3.py b/tests/configs/realview-switcheroo-o3.py
new file mode 100644
index 000000000..6079402e2
--- /dev/null
+++ b/tests/configs/realview-switcheroo-o3.py
@@ -0,0 +1,48 @@
+# Copyright (c) 2012 ARM Limited
+# All rights reserved.
+#
+# The license below extends only to copyright in the software and shall
+# not be construed as granting a license to any other intellectual
+# property including but not limited to intellectual property relating
+# to a hardware implementation of the functionality of the software
+# licensed hereunder.  You may use the software subject to the license
+# terms below provided that you ensure that this notice is replicated
+# unmodified and in its entirety in all distributions of the software,
+# modified or unmodified, in source code or in binary form.
+#
+# Redistribution and use in source and binary forms, with or without
+# 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
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution;
+# neither the name of the copyright holders nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# Authors: Andreas Sandberg
+
+from m5.objects import *
+from arm_generic import *
+import switcheroo
+
+root = LinuxArmFSSwitcheroo(
+    cpu_classes=(DerivO3CPU, DerivO3CPU)
+    ).create_root()
+
+# Setup a custom test method that uses the switcheroo tester that
+# switches between CPU models.
+run_test = switcheroo.run_test
diff --git a/tests/configs/realview-switcheroo-timing.py b/tests/configs/realview-switcheroo-timing.py
new file mode 100644
index 000000000..2329de6b0
--- /dev/null
+++ b/tests/configs/realview-switcheroo-timing.py
@@ -0,0 +1,48 @@
+# Copyright (c) 2012 ARM Limited
+# All rights reserved.
+#
+# The license below extends only to copyright in the software and shall
+# not be construed as granting a license to any other intellectual
+# property including but not limited to intellectual property relating
+# to a hardware implementation of the functionality of the software
+# licensed hereunder.  You may use the software subject to the license
+# terms below provided that you ensure that this notice is replicated
+# unmodified and in its entirety in all distributions of the software,
+# modified or unmodified, in source code or in binary form.
+#
+# Redistribution and use in source and binary forms, with or without
+# 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
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution;
+# neither the name of the copyright holders nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# Authors: Andreas Sandberg
+
+from m5.objects import *
+from arm_generic import *
+import switcheroo
+
+root = LinuxArmFSSwitcheroo(
+    cpu_classes=(TimingSimpleCPU, TimingSimpleCPU)
+    ).create_root()
+
+# Setup a custom test method that uses the switcheroo tester that
+# switches between CPU models.
+run_test = switcheroo.run_test
diff --git a/tests/configs/switcheroo.py b/tests/configs/switcheroo.py
new file mode 100644
index 000000000..dadf8db03
--- /dev/null
+++ b/tests/configs/switcheroo.py
@@ -0,0 +1,138 @@
+# Copyright (c) 2012 ARM Limited
+# All rights reserved.
+#
+# The license below extends only to copyright in the software and shall
+# not be construed as granting a license to any other intellectual
+# property including but not limited to intellectual property relating
+# to a hardware implementation of the functionality of the software
+# licensed hereunder.  You may use the software subject to the license
+# terms below provided that you ensure that this notice is replicated
+# unmodified and in its entirety in all distributions of the software,
+# modified or unmodified, in source code or in binary form.
+#
+# Redistribution and use in source and binary forms, with or without
+# 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
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution;
+# neither the name of the copyright holders nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# Authors: Andreas Sandberg
+
+import m5
+from m5.objects import *
+m5.util.addToPath('../configs/common')
+from Caches import *
+
+def _memMode(cclass):
+    if cclass == AtomicSimpleCPU:
+        return "atomic", m5.objects.params.atomic
+    else:
+        return "timing", m5.objects.params.timing
+
+class Sequential:
+    """Sequential CPU switcher.
+
+    The sequential CPU switches between all CPUs in a system in
+    order. The CPUs in the system must have been prepared for
+    switching, which in practice means that only one CPU is switched
+    in. base_config.BaseFSSwitcheroo can be used to create such a
+    system.
+    """
+    def __init__(self, cpus):
+        self.first_cpu = None
+        for (cpuno, cpu) in enumerate(cpus):
+            if not cpu.switched_out:
+                if self.first_cpu != None:
+                    fatal("More than one CPU is switched in");
+                self.first_cpu = cpuno
+
+        if self.first_cpu == None:
+            fatal("The system contains no switched in CPUs")
+
+        self.cur_cpu = self.first_cpu
+        self.cpus = cpus
+
+    def next(self):
+        self.cur_cpu = (self.cur_cpu + 1) % len(self.cpus)
+        return self.cpus[self.cur_cpu]
+
+    def first(self):
+        return self.cpus[self.first_cpu]
+
+def run_test(root, switcher=None, freq=1000):
+    """Test runner for CPU switcheroo tests.
+
+    The switcheroo test runner is used to switch CPUs in a system that
+    has been prepared for CPU switching. Such systems should have
+    multiple CPUs when they are instantiated, but only one should be
+    switched in. Such configurations can be created using the
+    base_config.BaseFSSwitcheroo class.
+
+    A CPU switcher object is used to control switching. The default
+    switcher sequentially switches between all CPUs in a system,
+    starting with the CPU that is currently switched in.
+
+    Unlike most other test runners, this one automatically configures
+    the memory mode of the system based on the first CPU the switcher
+    reports.
+
+    Keyword Arguments:
+      switcher -- CPU switcher implementation. See Sequential for
+                  an example implementation.
+      period -- Switching frequency in Hz.
+    """
+
+    if switcher == None:
+        switcher = Sequential(root.system.cpu)
+
+    current_cpu = switcher.first()
+    system = root.system
+    system.mem_mode = _memMode(type(current_cpu))[0]
+
+    # instantiate configuration
+    m5.instantiate()
+
+    # Determine the switching period, this has to be done after
+    # instantiating the system since the time base must be fixed.
+    period = m5.ticks.fromSeconds(1.0 / freq)
+    while True:
+        exit_event = m5.simulate(period)
+        exit_cause = exit_event.getCause()
+
+        if exit_cause == "simulate() limit reached":
+            next_cpu = switcher.next()
+
+            print "Switching CPUs..."
+            print "Next CPU: %s" % type(next_cpu)
+            m5.drain(system)
+            system.setMemoryMode(_memMode(type(next_cpu))[1])
+            if current_cpu != next_cpu:
+                m5.switchCpus([ (current_cpu, next_cpu) ])
+            else:
+                print "Source CPU and destination CPU are the same, skipping..."
+            m5.resume(system)
+            current_cpu = next_cpu
+        elif exit_cause == "target called exit()" or \
+                exit_cause == "m5_exit instruction encountered":
+
+            sys.exit(0)
+        else:
+            print "Test failed: Unknown exit cause: %s" % exit_cause
+            sys.exit(1)
diff --git a/tests/configs/tsunami-switcheroo-full.py b/tests/configs/tsunami-switcheroo-full.py
new file mode 100644
index 000000000..d2be0ebfa
--- /dev/null
+++ b/tests/configs/tsunami-switcheroo-full.py
@@ -0,0 +1,48 @@
+# Copyright (c) 2012 ARM Limited
+# All rights reserved.
+#
+# The license below extends only to copyright in the software and shall
+# not be construed as granting a license to any other intellectual
+# property including but not limited to intellectual property relating
+# to a hardware implementation of the functionality of the software
+# licensed hereunder.  You may use the software subject to the license
+# terms below provided that you ensure that this notice is replicated
+# unmodified and in its entirety in all distributions of the software,
+# modified or unmodified, in source code or in binary form.
+#
+# Redistribution and use in source and binary forms, with or without
+# 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
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution;
+# neither the name of the copyright holders nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# Authors: Andreas Sandberg
+
+from m5.objects import *
+from alpha_generic import *
+import switcheroo
+
+root = LinuxAlphaFSSwitcheroo(
+    cpu_classes=(AtomicSimpleCPU, TimingSimpleCPU, DerivO3CPU)
+    ).create_root()
+
+# Setup a custom test method that uses the switcheroo tester that
+# switches between CPU models.
+run_test = switcheroo.run_test