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Documentation: Add debugfs docs with run after boot

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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.

Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Rae Moar <rmoar@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
This commit is contained in:
Rae Moar 2023-12-13 19:44:21 +00:00 committed by Shuah Khan
parent c72a870926
commit e9f0e21ceb
1 changed files with 47 additions and 4 deletions
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51
Documentation/dev-tools/kunit/run_manual.rst
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@ -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.