Add an FAQ entry to the KUnit documentation with some tips for troubleshooting KUnit and kunit_tool.
These suggestions largely came from an email thread: https://lore.kernel.org/linux-kselftest/41db8bbd-3ba0-8bde-7352-083bf4b947ff...
Signed-off-by: David Gow davidgow@google.com Reviewed-by: Alan Maguire alan.maguire@oracle.com Reviewed-by: Brendan Higgins brendanhiggins@google.com --- Changes since v1[1] - Added a section about running KUnit outside UML (based heavily on Alan's suggestion in the thread).
[1]: https://lore.kernel.org/linux-kselftest/20200602054216.93122-1-davidgow@goog...
Documentation/dev-tools/kunit/faq.rst | 40 +++++++++++++++++++++++++++ 1 file changed, 40 insertions(+)
diff --git a/Documentation/dev-tools/kunit/faq.rst b/Documentation/dev-tools/kunit/faq.rst index ea55b2467653..1628862e7024 100644 --- a/Documentation/dev-tools/kunit/faq.rst +++ b/Documentation/dev-tools/kunit/faq.rst @@ -61,3 +61,43 @@ test, or an end-to-end test. kernel by installing a production configuration of the kernel on production hardware with a production userspace and then trying to exercise some behavior that depends on interactions between the hardware, the kernel, and userspace. + +KUnit isn't working, what should I do? +====================================== + +Unfortunately, there are a number of things which can break, but here are some +things to try. + +1. Try running ``./tools/testing/kunit/kunit.py run`` with the ``--raw_output`` + parameter. This might show details or error messages hidden by the kunit_tool + parser. +2. Instead of running ``kunit.py run``, try running ``kunit.py config``, + ``kunit.py build``, and ``kunit.py exec`` independently. This can help track + down where an issue is occurring. (If you think the parser is at fault, you + can run it manually against stdin or a file with ``kunit.py parse``.) +3. Running the UML kernel directly can often reveal issues or error messages + kunit_tool ignores. This should be as simple as running ``./vmlinux`` after + building the UML kernel (e.g., by using ``kunit.py build``). Note that UML + has some unusual requirements (such as the host having a tmpfs filesystem + mounted), and has had issues in the past when built statically and the host + has KASLR enabled. (On older host kernels, you may need to run ``setarch + `uname -m` -R ./vmlinux`` to disable KASLR.) +4. Make sure the kernel .config has ``CONFIG_KUNIT=y`` and at least one test + (e.g. ``CONFIG_KUNIT_EXAMPLE_TEST=y``). kunit_tool will keep its .config + around, so you can see what config was used after running ``kunit.py run``. + It also preserves any config changes you might make, so you can + enable/disable things with ``make ARCH=um menuconfig`` or similar, and then + re-run kunit_tool. +5. Try to run ``make ARCH=um defconfig`` before running ``kunit.py run``. This + may help clean up any residual config items which could be causing problems. +6. Finally, try running KUnit outside UML. KUnit and KUnit tests can run be + built into any kernel, or can be built as a module and loaded at runtime. + Doing so should allow you to determine if UML is causing the issue you're + seeing. When tests are built-in, they will execute when the kernel boots, and + modules will automatically execute associated tests when loaded. Test results + can be collected from ``/sys/kernel/debug/kunit/<test suite>/results``, and + can be parsed with ``kunit.py parse``. For more details, see "KUnit on + non-UML architectures" in :doc:`usage`. + +If none of the above tricks help, you are always welcome to email any issues to +kunit-dev@googlegroups.com.