.. SPDX-License-Identifier: GPL-2.0
=============================
Running 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::
Configuring KUnit Kernel ...
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
Creating 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``.
Configuring, building, and running 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: **Running tests with kunit_tool**,
is equivalent to running the above three commands in sequence.
Parsing 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
Filtering tests
===============
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.
.. _kunit-on-qemu:
Running 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
Running 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``: Enable a predefined set of options in order to build
as many tests as possible.
.. note:: The list of enabled options can be found in
``tools/testing/kunit/configs/all_tests.config``.
If you only want to enable all tests with otherwise satisfied
dependencies, instead add ``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.
- ``--filter``: Specifies filters on test attributes, for example, ``speed!=slow``.
Multiple filters can be used by wrapping input in quotes and separating filters
by commas. Example: ``--filter "speed>slow, module=example"``.
- ``--filter_action``: If set to ``skip``, filtered tests will be shown as skipped
in the output rather than showing no output.
- ``--list_tests``: If set, lists all tests that will be run.
- ``--list_tests_attr``: If set, lists all tests that will be run and all of their
attributes.
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