.. SPDX-License-Identifier: GPL-2.0 ========================= Run Tests with kunit_tool ========================= We can either run KUnit tests using kunit_tool or can run tests manually, and then use kunit_tool to parse the results. To run tests manually, see: Documentation/dev-tools/kunit/run_manual.rst. As long as we can build the kernel, we can run KUnit. kunit_tool is a Python script which configures and builds a kernel, runs tests, and formats the test results. Run command: .. code-block:: ./tools/testing/kunit/kunit.py run We should see the following: .. code-block:: Generating .config... Building KUnit kernel... Starting KUnit kernel... We may want to use the following options: .. code-block:: ./tools/testing/kunit/kunit.py run --timeout=30 --jobs=`nproc --all` - ``--timeout`` sets a maximum amount of time for tests to run. - ``--jobs`` sets the number of threads to build the kernel. kunit_tool will generate a ``.kunitconfig`` with a default configuration, if no other ``.kunitconfig`` file exists (in the build directory). In addition, it verifies that the generated ``.config`` file contains the ``CONFIG`` options in the ``.kunitconfig``. It is also possible to pass a separate ``.kunitconfig`` fragment to kunit_tool. This is useful if we have several different groups of tests we want to run independently, or if we want to use pre-defined test configs for certain subsystems. To use a different ``.kunitconfig`` file (such as one provided to test a particular subsystem), pass it as an option: .. code-block:: ./tools/testing/kunit/kunit.py run --kunitconfig=fs/ext4/.kunitconfig To view kunit_tool flags (optional command-line arguments), run: .. code-block:: ./tools/testing/kunit/kunit.py run --help Create a ``.kunitconfig`` File =============================== If we want to run a specific set of tests (rather than those listed in the KUnit ``defconfig``), we can provide Kconfig options in the ``.kunitconfig`` file. For default .kunitconfig, see: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/kunit/configs/default.config. A ``.kunitconfig`` is a ``minconfig`` (a .config generated by running ``make savedefconfig``), used for running a specific set of tests. This file contains the regular Kernel configs with specific test targets. The ``.kunitconfig`` also contains any other config options required by the tests (For example: dependencies for features under tests, configs that enable/disable certain code blocks, arch configs and so on). To create a ``.kunitconfig``, using the KUnit ``defconfig``: .. code-block:: cd $PATH_TO_LINUX_REPO cp tools/testing/kunit/configs/default.config .kunit/.kunitconfig We can then add any other Kconfig options. For example: .. code-block:: CONFIG_LIST_KUNIT_TEST=y kunit_tool ensures that all config options in ``.kunitconfig`` are set in the kernel ``.config`` before running the tests. It warns if we have not included the options dependencies. .. note:: Removing something from the ``.kunitconfig`` will not rebuild the ``.config file``. The configuration is only updated if the ``.kunitconfig`` is not a subset of ``.config``. This means that we can use other tools (For example: ``make menuconfig``) to adjust other config options. The build dir needs to be set for ``make menuconfig`` to work, therefore by default use ``make O=.kunit menuconfig``. Configure, Build, and Run Tests =============================== If we want to make manual changes to the KUnit build process, we can run part of the KUnit build process independently. When running kunit_tool, from a ``.kunitconfig``, we can generate a ``.config`` by using the ``config`` argument: .. code-block:: ./tools/testing/kunit/kunit.py config To build a KUnit kernel from the current ``.config``, we can use the ``build`` argument: .. code-block:: ./tools/testing/kunit/kunit.py build If we already have built UML kernel with built-in KUnit tests, we can run the kernel, and display the test results with the ``exec`` argument: .. code-block:: ./tools/testing/kunit/kunit.py exec The ``run`` command discussed in section: **Run Tests with kunit_tool**, is equivalent to running the above three commands in sequence. Parse Test Results ================== KUnit tests output displays results in TAP (Test Anything Protocol) format. When running tests, kunit_tool parses this output and prints a summary. To see the raw test results in TAP format, we can pass the ``--raw_output`` argument: .. code-block:: ./tools/testing/kunit/kunit.py run --raw_output If we have KUnit results in the raw TAP format, we can parse them and print the human-readable summary with the ``parse`` command for kunit_tool. This accepts a filename for an argument, or will read from standard input. .. code-block:: bash # Reading from a file ./tools/testing/kunit/kunit.py parse /var/log/dmesg # Reading from stdin dmesg | ./tools/testing/kunit/kunit.py parse Run Selected Test Suites ======================== By passing a bash style glob filter to the ``exec`` or ``run`` commands, we can run a subset of the tests built into a kernel . For example: if we only want to run KUnit resource tests, use: .. code-block:: ./tools/testing/kunit/kunit.py run 'kunit-resource*' This uses the standard glob format with wildcard characters. Run Tests on qemu ================= kunit_tool supports running tests on qemu as well as via UML. To run tests on qemu, by default it requires two flags: - ``--arch``: Selects a configs collection (Kconfig, qemu config options and so on), that allow KUnit tests to be run on the specified architecture in a minimal way. The architecture argument is same as the option name passed to the ``ARCH`` variable used by Kbuild. Not all architectures currently support this flag, but we can use ``--qemu_config`` to handle it. If ``um`` is passed (or this flag is ignored), the tests will run via UML. Non-UML architectures, for example: i386, x86_64, arm and so on; run on qemu. - ``--cross_compile``: Specifies the Kbuild toolchain. It passes the same argument as passed to the ``CROSS_COMPILE`` variable used by Kbuild. As a reminder, this will be the prefix for the toolchain binaries such as GCC. For example: - ``sparc64-linux-gnu`` if we have the sparc toolchain installed on our system. - ``$HOME/toolchains/microblaze/gcc-9.2.0-nolibc/microblaze-linux/bin/microblaze-linux`` if we have downloaded the microblaze toolchain from the 0-day website to a directory in our home directory called toolchains. This means that for most architectures, running under qemu is as simple as: .. code-block:: bash ./tools/testing/kunit/kunit.py run --arch=x86_64 When cross-compiling, we'll likely need to specify a different toolchain, for example: .. code-block:: bash ./tools/testing/kunit/kunit.py run \ --arch=s390 \ --cross_compile=s390x-linux-gnu- If we want to run KUnit tests on an architecture not supported by the ``--arch`` flag, or want to run KUnit tests on qemu using a non-default configuration; then we can write our own``QemuConfig``. These ``QemuConfigs`` are written in Python. They have an import line ``from..qemu_config import QemuArchParams`` at the top of the file. The file must contain a variable called ``QEMU_ARCH`` that has an instance of ``QemuArchParams`` assigned to it. See example in: ``tools/testing/kunit/qemu_configs/x86_64.py``. Once we have a ``QemuConfig``, we can pass it into kunit_tool, using the ``--qemu_config`` flag. When used, this flag replaces the ``--arch`` flag. For example: using ``tools/testing/kunit/qemu_configs/x86_64.py``, the invocation appear as .. code-block:: bash ./tools/testing/kunit/kunit.py run \ --timeout=60 \ --jobs=12 \ --qemu_config=./tools/testing/kunit/qemu_configs/x86_64.py Command-Line Arguments ====================== kunit_tool has a number of other command-line arguments which can be useful for our test environment. Below are the most commonly used command line arguments: - ``--help``: Lists all available options. To list common options, place ``--help`` before the command. To list options specific to that command, place ``--help`` after the command. .. note:: Different commands (``config``, ``build``, ``run``, etc) have different supported options. - ``--build_dir``: Specifies kunit_tool build directory. It includes the ``.kunitconfig``, ``.config`` files and compiled kernel. - ``--make_options``: Specifies additional options to pass to make, when compiling a kernel (using ``build`` or ``run`` commands). For example: to enable compiler warnings, we can pass ``--make_options W=1``. - ``--alltests``: Builds a UML kernel with all config options enabled using ``make allyesconfig``. This allows us to run as many tests as possible. .. note:: It is slow and prone to breakage as new options are added or modified. Instead, enable all tests which have satisfied dependencies by adding ``CONFIG_KUNIT_ALL_TESTS=y`` to your ``.kunitconfig``. - ``--kunitconfig``: Specifies the path or the directory of the ``.kunitconfig`` file. For example: - ``lib/kunit/.kunitconfig`` can be the path of the file. - ``lib/kunit`` can be the directory in which the file is located. This file is used to build and run with a predefined set of tests and their dependencies. For example, to run tests for a given subsystem. - ``--kconfig_add``: Specifies additional configuration options to be appended to the ``.kunitconfig`` file. For example: .. code-block:: ./tools/testing/kunit/kunit.py run --kconfig_add CONFIG_KASAN=y - ``--arch``: Runs tests on the specified architecture. The architecture argument is same as the Kbuild ARCH environment variable. For example, i386, x86_64, arm, um, etc. Non-UML architectures run on qemu. Default is `um`. - ``--cross_compile``: Specifies the Kbuild toolchain. It passes the same argument as passed to the ``CROSS_COMPILE`` variable used by Kbuild. This will be the prefix for the toolchain binaries such as GCC. For example: - ``sparc64-linux-gnu-`` if we have the sparc toolchain installed on our system. - ``$HOME/toolchains/microblaze/gcc-9.2.0-nolibc/microblaze-linux/bin/microblaze-linux`` if we have downloaded the microblaze toolchain from the 0-day website to a specified path in our home directory called toolchains. - ``--qemu_config``: Specifies the path to a file containing a custom qemu architecture definition. This should be a python file containing a `QemuArchParams` object. - ``--qemu_args``: Specifies additional qemu arguments, for example, ``-smp 8``. - ``--jobs``: Specifies the number of jobs (commands) to run simultaneously. By default, this is set to the number of cores on your system. - ``--timeout``: Specifies the maximum number of seconds allowed for all tests to run. This does not include the time taken to build the tests. - ``--kernel_args``: Specifies additional kernel command-line arguments. May be repeated. - ``--run_isolated``: If set, boots the kernel for each individual suite/test. This is useful for debugging a non-hermetic test, one that might pass/fail based on what ran before it. - ``--raw_output``: If set, generates unformatted output from kernel. Possible options are: - ``all``: To view the full kernel output, use ``--raw_output=all``. - ``kunit``: This is the default option and filters to KUnit output. Use ``--raw_output`` or ``--raw_output=kunit``. - ``--json``: If set, stores the test results in a JSON format and prints to `stdout` or saves to a file if a filename is specified.