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@xxxxxxxxx/T/#m23213d4e156db6d59b0b460a9014950f5ff6eb03 > > Signed-off-by: David Gow <davidgow@xxxxxxxxxx> > --- > 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@xxxxxxxxxx>
