tests/functional: add e2e test for dynamic QMP monitor hotplug
Add functional tests that exercise dynamic monitor hotplug with real socket connections: - Hotplug cycle: chardev-add a unix socket, object-add, connect to the socket, receive the QMP greeting, negotiate capabilities, send query-version, disconnect, remove the monitor and chardev, then repeat the entire cycle a second time to verify cleanup and reuse. - Self-removal: a dynamically-added monitor sends object-del targeting itself, verifying that the request is rejected - Large response: send query-qmp-schema on a dynamic monitor to exercise the output buffer flush path with a large response payload. - Events after negotiation: trigger STOP/RESUME events via the main monitor and verify they are delivered on the dynamic monitor. This complements the qtest unit tests by verifying that a real QMP client can connect to a dynamically-added monitor and exchange messages. Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> [DB: modified to use object-add/object-del; adjust self-removal test to validate rejection of request] Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Tested-by: Peter Krempa <pkrempa@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Message-ID: <20260706135824.2623960-30-berrange@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
Christian Brauner committed
Jul 6, 2026 at 14:58 UTC
f9827a9b9a9463b46411ac8c9efc7c911d7caf17
3 files changed
+170
MAINTAINERS
+1
@@ -3672,6 +3672,7 @@ F: docs/interop/*qmp-*
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F: scripts/qmp/
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F: tests/qtest/qmp-test.c
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F: tests/qtest/qmp-cmd-test.c
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+F: tests/functional/generic/test_monitor_hotplug.py
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T: git https://repo.or.cz/qemu/armbru.git qapi-next
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qtest
tests/functional/generic/meson.build
+1
@@ -4,6 +4,7 @@ tests_generic_system = [
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'empty_cpu_model',
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'info_usernet',
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'linters',
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+ 'monitor_hotplug',
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'version',
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'vnc',
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]
tests/functional/generic/test_monitor_hotplug.py
new
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@@ -0,0 +1,168 @@
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+#!/usr/bin/env python3
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+#
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+# SPDX-License-Identifier: GPL-2.0-or-later
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+#
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+# Functional test for dynamic QMP monitor hotplug
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+#
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+# Copyright (c) 2026 Christian Brauner
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+
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+import os
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+
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+from qemu_test import QemuSystemTest
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+
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+from qemu.qmp.legacy import QEMUMonitorProtocol
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+
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+
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+class MonitorHotplug(QemuSystemTest):
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+
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+ def setUp(self):
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+ super().setUp()
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+ sock_dir = self.socket_dir()
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+ self._sock_path = os.path.join(sock_dir.name, 'hotplug.sock')
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+
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+ def _add_monitor(self):
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+ """Create a chardev + monitor and return the socket path."""
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+ sock = self._sock_path
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+ self.vm.cmd('chardev-add', id='hotplug-chr', backend={
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+ 'type': 'socket',
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+ 'data': {
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+ 'addr': {
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+ 'type': 'unix',
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+ 'data': {'path': sock}
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+ },
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+ 'server': True,
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+ 'wait': False,
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+ }
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+ })
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+ self.vm.cmd('object-add', id='hotplug-mon',
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+ qom_type='monitor-qmp',
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+ chardev='hotplug-chr')
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+ return sock
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+
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+ def _remove_monitor(self):
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+ """Remove the monitor + chardev."""
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+ self.vm.cmd('object-del', id='hotplug-mon')
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+ self.vm.cmd('chardev-remove', id='hotplug-chr')
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+
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+ def _connect_and_handshake(self, sock_path):
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+ """
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+ Connect to the dynamic monitor socket, perform the QMP
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+ greeting and capability negotiation, send a command, then
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+ disconnect.
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+ """
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+ qmp = QEMUMonitorProtocol(sock_path)
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+
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+ # connect(negotiate=True) receives the greeting, validates it,
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+ # and sends qmp_capabilities automatically.
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+ greeting = qmp.connect(negotiate=True)
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+ self.assertIn('QMP', greeting)
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+ self.assertIn('version', greeting['QMP'])
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+ self.assertIn('capabilities', greeting['QMP'])
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+
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+ # Send a real command to prove the session is fully functional
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+ resp = qmp.cmd_obj({'execute': 'query-version'})
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+ self.assertIn('return', resp)
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+ self.assertIn('qemu', resp['return'])
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+
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+ qmp.close()
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+
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+ def test_hotplug_cycle(self):
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+ """
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+ Hotplug a monitor, do the full QMP handshake, unplug it,
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+ then repeat the whole cycle a second time.
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+ """
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+ self.set_machine('none')
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+ self.vm.add_args('-nodefaults')
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+ self.vm.launch()
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+
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+ # First cycle
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+ sock = self._add_monitor()
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+ self._connect_and_handshake(sock)
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+ self._remove_monitor()
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+
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+ # Second cycle -- same ids, same path, must work
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+ sock = self._add_monitor()
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+ self._connect_and_handshake(sock)
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+ self._remove_monitor()
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+
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+ def test_self_removal(self):
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+ """
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+ A dynamically-added monitor sends object-del targeting
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+ itself. Verify the request is rejected, but the monitor
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+ can still be deleted from outside its own context.
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+ """
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+ self.set_machine('none')
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+ self.vm.add_args('-nodefaults')
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+ self.vm.launch()
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+
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+ sock = self._add_monitor()
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+
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+ qmp = QEMUMonitorProtocol(sock)
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+ greeting = qmp.connect(negotiate=True)
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+ self.assertIn('QMP', greeting)
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+
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+ # Self-removal: the dynamic monitor raises error
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+ resp = qmp.cmd_obj({'execute': 'object-del',
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+ 'arguments': {'id': 'hotplug-mon'}})
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+ self.assertIn('error', resp)
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+
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+ qmp.close()
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+
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+ resp = self.vm.cmd('object-del', id='hotplug-mon')
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+
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+ # Clean up the chardev
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+ self.vm.cmd('chardev-remove', id='hotplug-chr')
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+
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+ def test_large_response(self):
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+ """
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+ Send a command with a large response (query-qmp-schema) on a
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+ dynamically-added monitor to exercise the output buffer flush
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+ path.
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+ """
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+ self.set_machine('none')
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+ self.vm.add_args('-nodefaults')
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+ self.vm.launch()
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+
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+ sock = self._add_monitor()
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+
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+ qmp = QEMUMonitorProtocol(sock)
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+ qmp.connect(negotiate=True)
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+
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+ resp = qmp.cmd_obj({'execute': 'query-qmp-schema'})
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+ self.assertIn('return', resp)
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+ self.assertIsInstance(resp['return'], list)
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+ self.assertGreater(len(resp['return']), 0)
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+
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+ qmp.close()
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+ self._remove_monitor()
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+
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+ def test_events_after_negotiation(self):
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+ """
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+ Verify that QMP events are delivered on a dynamically-added
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+ monitor after capability negotiation completes.
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+ """
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+ self.set_machine('none')
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+ self.vm.add_args('-nodefaults')
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+ self.vm.launch()
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+
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+ sock = self._add_monitor()
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+
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+ qmp = QEMUMonitorProtocol(sock)
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+ qmp.connect(negotiate=True)
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+
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+ # Trigger a STOP event via the main monitor, then read it
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+ # from the dynamic monitor.
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+ self.vm.cmd('stop')
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+ resp = qmp.pull_event(wait=True)
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+ self.assertEqual(resp['event'], 'STOP')
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+
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+ self.vm.cmd('cont')
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+ resp = qmp.pull_event(wait=True)
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+ self.assertEqual(resp['event'], 'RESUME')
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+
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+ qmp.close()
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+ self._remove_monitor()
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+
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+
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+if __name__ == '__main__':
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+ QemuSystemTest.main()