Re: [PATCH v4 6/6] Documentation: Add debugfs docs with run after boot

[David Gow <davidgow@google.com>]

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On Wed, 13 Dec 2023 at 09:02, Rae Moar <rmoar@google.com> wrote:
>
> Expand the documentation on the KUnit debugfs filesystem on the
> run_manual.rst page.
>
> Add section describing how to access results using debugfs.
>
> Add section describing how to run tests after boot using debugfs.
>
> Signed-off-by: Rae Moar <rmoar@google.com>
> ---

Looks good!

Reviewed-by: David Gow <davidgow@google.com>

Thanks,
-- David


> Changes since v3:
> - Change the introduction of the debugfs section
> - Add detail to not being able to run concurrently or run with init data
>
>  Documentation/dev-tools/kunit/run_manual.rst | 51 ++++++++++++++++++--
>  1 file changed, 47 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/dev-tools/kunit/run_manual.rst b/Documentation/dev-tools/kunit/run_manual.rst
> index e7b46421f247..699d92885075 100644
> --- a/Documentation/dev-tools/kunit/run_manual.rst
> +++ b/Documentation/dev-tools/kunit/run_manual.rst
> @@ -49,9 +49,52 @@ loaded.
>
>  The results will appear in TAP format in ``dmesg``.
>
> +debugfs
> +=======
> +
> +KUnit can be accessed from userspace via the debugfs filesystem (See more
> +information about debugfs at Documentation/filesystems/debugfs.rst).
> +
> +If ``CONFIG_KUNIT_DEBUGFS`` is enabled, the KUnit debugfs filesystem is
> +mounted at /sys/kernel/debug/kunit. You can use this filesystem to perform
> +the following actions.
> +
> +Retrieve Test Results
> +=====================
> +
> +You can use debugfs to retrieve KUnit test results. The test results are
> +accessible from the debugfs filesystem in the following read-only file:
> +
> +.. code-block :: bash
> +
> +       /sys/kernel/debug/kunit/<test_suite>/results
> +
> +The test results are printed in a KTAP document. Note this document is separate
> +to the kernel log and thus, may have different test suite numbering.
> +
> +Run Tests After Kernel Has Booted
> +=================================
> +
> +You can use the debugfs filesystem to trigger built-in tests to run after
> +boot. To run the test suite, you can use the following command to write to
> +the ``/sys/kernel/debug/kunit/<test_suite>/run`` file:
> +
> +.. code-block :: bash
> +
> +       echo "any string" > /sys/kernel/debugfs/kunit/<test_suite>/run
> +
> +As a result, the test suite runs and the results are printed to the kernel
> +log.
> +
> +However, this feature is not available with KUnit suites that use init data,
> +because init data may have been discarded after the kernel boots. KUnit
> +suites that use init data should be defined using the
> +kunit_test_init_section_suites() macro.
> +
> +Also, you cannot use this feature to run tests concurrently. Instead a test
> +will wait to run until other tests have completed or failed.
> +
>  .. note ::
>
> -       If ``CONFIG_KUNIT_DEBUGFS`` is enabled, KUnit test results will
> -       be accessible from the ``debugfs`` filesystem (if mounted).
> -       They will be in ``/sys/kernel/debug/kunit/<test_suite>/results``, in
> -       TAP format.
> +       For test authors, to use this feature, tests will need to correctly initialise
> +       and/or clean up any data, so the test runs correctly a second time.
> --
> 2.43.0.472.g3155946c3a-goog
>

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