qemudriver: Support interactions via monitor_command before spinning off the instance.

Signed-off-by: Joschka Seydell <[email protected]>

Author: JSydll

doc/configuration.rst

@@ -2867,6 +2867,10 @@ The QEMUDriver also requires the specification of:
   specify the build device tree
 - a path key, this is the path to the rootfs
 
+To allow interactions with a prepared, not yet started QEMU instance, the ``prepare()`` method
+can be explicitly called, after which ``monitor_command(...)`` can be run before eventually
+releasing the CPU(s) via ``on()``.
+
 SigrokDriver
 ~~~~~~~~~~~~
 The :any:`SigrokDriver` uses a `SigrokDevice`_ resource to record samples and provides

labgrid/driver/qemudriver.py

@@ -259,9 +259,9 @@ def on_deactivate(self):
         shutil.rmtree(self._tempdir)
 
     @step()
-    def on(self):
-        """Start the QEMU subprocess, accept the unix socket connection and
-        afterwards start the emulator using a QMP Command"""
+    def prepare(self):
+        """Start the QEMU subprocess and accept the unix socket connection
+        if not already prepared."""
         if self.status:
             return
         self.logger.debug("Starting with: %s", self._cmd)
@@ -287,7 +287,14 @@ def on(self):
 
         # Restore port forwards
         for v in self._forwarded_ports.values():
-            self._add_port_forward(*v)
+            self._add_port_forward(*v) 
+
+    @step()
+    def on(self):
+        """Prepare the instance (only if not done already) and start the emulator
+        using a QMP Command"""
+        if not self._child:
+            self.prepare()
 
         self.monitor_command("cont")
 

tests/test_qemudriver.py

@@ -1,6 +1,7 @@
 import pytest
 
 from labgrid.driver import QEMUDriver
+from labgrid.driver.exception import ExecutionError
 from labgrid import Environment
 
 @pytest.fixture
@@ -61,6 +62,12 @@ def qemu_mock(mocker):
     socket_mock = mocker.patch('socket.socket')
     socket_mock.return_value.accept.return_value = mocker.MagicMock(), ''
 
+@pytest.fixture
+def qemu_qmp_mock(mocker):
+    monitor_mock = mocker.patch('labgrid.driver.qemudriver.QMPMonitor')
+    monitor_mock.return_value.execute.return_value = {'return': {}}
+    return monitor_mock
+
 @pytest.fixture
 def qemu_version_mock(mocker):
     run_mock = mocker.patch('subprocess.run')
@@ -91,6 +98,27 @@ def test_qemu_on_off(qemu_target, qemu_driver, qemu_mock, qemu_version_mock):
 
     qemu_target.deactivate(qemu_driver)
 
+def test_qemu_prepare(qemu_target, qemu_driver, qemu_mock, qemu_version_mock):
+    qemu_target.activate(qemu_driver)
+
+    qemu_driver.prepare()
+    qemu_driver.on()
+
+def test_qemu_monitor_command_without_prepare(qemu_target, qemu_driver, qemu_mock, qemu_version_mock, qemu_qmp_mock):
+    qemu_target.activate(qemu_driver)
+
+    with pytest.raises(ExecutionError):
+        qemu_driver.monitor_command("info")
+        qemu_qmp_mock.assert_not_called()
+
+def test_qemu_prepare_with_monitor_command(qemu_target, qemu_driver, qemu_mock, qemu_version_mock, qemu_qmp_mock):
+    qemu_target.activate(qemu_driver)
+
+    qemu_driver.prepare()
+    qemu_driver.monitor_command("info")
+    qemu_qmp_mock.assert_called_once()
+    qemu_qmp_mock.return_value.execute.assert_called_with("info", {})
+
 def test_qemu_read_write(qemu_target, qemu_driver, qemu_mock, qemu_version_mock):
     qemu_target.activate(qemu_driver)