On Mon, 1 Jun 2020, David Gow wrote:

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

Documentation/dev-tools/kunit/faq.rst | 32 +++++++++++++++++++++++++++ 1 file changed, 32 insertions(+)

diff --git a/Documentation/dev-tools/kunit/faq.rst b/Documentation/dev-tools/kunit/faq.rst index ea55b2467653..40109d425988 100644 --- a/Documentation/dev-tools/kunit/faq.rst +++ b/Documentation/dev-tools/kunit/faq.rst @@ -61,3 +61,35 @@ 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. Finally, running ``make ARCH=um defconfig`` before running ``kunit.py run``

• may help clean up any residual config items which could be causing problems.

Looks great! Could we add something like:

6. Try running kunit standalone (without UML). KUnit and associated tests can be built into a standard kernel or built as a module; doing so allows us to verify test behaviour independent of UML so can be useful to do if running under UML is failing. When tests are built-in they will execute on boot, and modules will automatically execute associated tests when loaded. Test results can be collected from /sys/kernel/debug/kunit/<test-suite>/results. For more details see "KUnit on non-UML architectures" in :doc:`usage`.

Reviewed-by: Alan Maguire alan.maguire@oracle.com