From 1a8755a51eef11360af92adf71fed6a20a1260b2 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Date: Thu, 21 Nov 2024 16:57:44 +0000 Subject: [PATCH] tests/functional: add a QMP backdoor for debugging stalled tests MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Support the QEMU_TEST_QMP_BACKDOOR=backdoor.sock env variable as a way to get a QMP backdoor for debugging a stalled QEMU test. Most typically this would be used if running the tests directly: $ QEMU_TEST_QMP_BACKDOOR=backdoor.sock \ QEMU_TEST_QEMU_BINARY=./build/qemu-system-arm \ PYTHONPATH=./python \ ./tests/functional/test_arm_tuxrun.py And then, when the test stalls, in a second shell run: $ ./scripts/qmp/qmp-shell backdoor.sock Signed-off-by: Daniel P. Berrangé Message-Id: <20241121154218.1423005-18-berrange@redhat.com> Reviewed-by: Thomas Huth Signed-off-by: Alex Bennée Message-Id: <20241121165806.476008-18-alex.bennee@linaro.org> --- docs/devel/testing/functional.rst | 10 ++++++++++ tests/functional/qemu_test/testcase.py | 7 +++++++ 2 files changed, 17 insertions(+) diff --git a/docs/devel/testing/functional.rst b/docs/devel/testing/functional.rst index 6b5d0c5b98..b8ad7b0bf7 100644 --- a/docs/devel/testing/functional.rst +++ b/docs/devel/testing/functional.rst @@ -176,6 +176,16 @@ primarily depend on the value of the ``qemu_bin`` class attribute. If it is not explicitly set by the test code, its default value will be the result the QEMU_TEST_QEMU_BINARY environment variable. +Debugging hung QEMU +^^^^^^^^^^^^^^^^^^^ + +When test cases go wrong it may be helpful to debug a stalled QEMU +process. While the QEMUMachine class owns the primary QMP monitor +socket, it is possible to request a second QMP monitor be created +by setting the ``QEMU_TEST_QMP_BACKDOOR`` env variable to refer +to a UNIX socket name. The ``qmp-shell`` command can then be +attached to the stalled QEMU to examine its live state. + Attribute reference ------------------- diff --git a/tests/functional/qemu_test/testcase.py b/tests/functional/qemu_test/testcase.py index e2a329c3e5..fceafb32b0 100644 --- a/tests/functional/qemu_test/testcase.py +++ b/tests/functional/qemu_test/testcase.py @@ -175,6 +175,13 @@ class QemuSystemTest(QemuBaseTest): log_dir=self.logdir) self.log.debug('QEMUMachine "%s" created', name) self.log.debug('QEMUMachine "%s" temp_dir: %s', name, vm.temp_dir) + + sockpath = os.environ.get("QEMU_TEST_QMP_BACKDOOR", None) + if sockpath is not None: + vm.add_args("-chardev", + f"socket,id=backdoor,path={sockpath},server=on,wait=off", + "-mon", "chardev=backdoor,mode=control") + if args: vm.add_args(*args) return vm