Gem5Device: Refactor into BaseGem5Device, Gem5LinuxDevice and Gem5AndroidDevice

- Refactored the Gem5Device to avoid duplicated code. There is now a
  BaseGem5Device which includes all of the shared functionality. The
  Gem5LinuxDevice and the Gem5AndroidDevice both inherit from
  BaseGem5Device, and LinuxDevice or AndroidDevice, respectively.

wlauto/devices/linux/gem5/__init__.py

@@ -0,0 +1,112 @@
+#    Copyright 2014-2015 ARM Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# Original implementation by Rene de Jong. Updated by Sascha Bischoff.
+
+import logging
+
+from wlauto import LinuxDevice, Parameter
+from wlauto.common.gem5.device import BaseGem5Device
+
+
+class Gem5LinuxDevice(BaseGem5Device, LinuxDevice):
+    """
+    Implements gem5 Linux device.
+
+    This class allows a user to connect WA to a simulation using gem5. The
+    connection to the device is made using the telnet connection of the
+    simulator, and is used for all commands. The simulator does not have ADB
+    support, and therefore we need to fall back to using standard shell
+    commands.
+
+    Files are copied into the simulation using a VirtIO 9P device in gem5. Files
+    are copied out of the simulated environment using the m5 writefile command
+    within the simulated system.
+
+    When starting the workload run, the simulator is automatically started by
+    Workload Automation, and a connection to the simulator is established. WA
+    will then wait for Android to boot on the simulated system (which can take
+    hours), prior to executing any other commands on the device. It is also
+    possible to resume from a checkpoint when starting the simulation. To do
+    this, please append the relevant checkpoint commands from the gem5
+    simulation script to the gem5_discription argument in the agenda.
+
+    Host system requirements:
+        * VirtIO support. We rely on diod on the host system. This can be
+          installed on ubuntu using the following command:
+
+                sudo apt-get install diod
+
+    Guest requirements:
+        * VirtIO support. We rely on VirtIO to move files into the simulation.
+          Please make sure that the following are set in the kernel
+          configuration:
+
+                CONFIG_NET_9P=y
+
+                CONFIG_NET_9P_VIRTIO=y
+
+                CONFIG_9P_FS=y
+
+                CONFIG_9P_FS_POSIX_ACL=y
+
+                CONFIG_9P_FS_SECURITY=y
+
+                CONFIG_VIRTIO_BLK=y
+
+        * m5 binary. Please make sure that the m5 binary is on the device and
+          can by found in the path.
+        * Busybox. Due to restrictions, we assume that busybox is installed in
+          the guest system, and can be found in the path.
+    """
+
+    name = 'gem5_linux'
+    platform = 'linux'
+
+    parameters = [
+        Parameter('core_names', default=[], override=True),
+        Parameter('core_clusters', default=[], override=True),
+        Parameter('host', default='localhost', override=True,
+                  description='Host name or IP address for the device.'),
+    ]
+
+    # Overwritten from Device. For documentation, see corresponding method in
+    # Device.
+
+    def __init__(self, **kwargs):
+        self.logger = logging.getLogger('Gem5LinuxDevice')
+        LinuxDevice.__init__(self, **kwargs)
+        BaseGem5Device.__init__(self, **kwargs)
+
+    def login_to_device(self):
+        # Wait for the login prompt
+        i = self.sckt.expect([r'login:', r'username:', self.sckt.UNIQUE_PROMPT],
+                             timeout=10)
+        # Check if we are already at a prompt, or if we need to log in.
+        if i < 2:
+            self.sckt.sendline("{}".format(self.username))
+            j = self.sckt.expect([r'password:', r'# ', self.sckt.UNIQUE_PROMPT],
+                                 timeout=self.delay)
+            if j == 2:
+                self.sckt.sendline("{}".format(self.password))
+                self.sckt.expect([r'# ', self.sckt.UNIQUE_PROMPT], timeout=self.delay)
+
+    def capture_screen(self, filepath):
+        if BaseGem5Device.capture_screen(self, filepath):
+            return
+
+        # If we didn't manage to do the above, call the parent class.
+        self.logger.warning("capture_screen: falling back to parent class implementation")
+        LinuxDevice.capture_screen(self, filepath)