TL;DR: Add support to kunit_tool to dispatch tests via QEMU. Also add support to immediately shutdown a kernel after running KUnit tests.
Background ----------
KUnit has supported running on all architectures for quite some time; however, kunit_tool - the script commonly used to invoke KUnit tests - has only fully supported KUnit run on UML. Its functionality has been broken up for some time to separate the configure, build, run, and parse phases making it possible to be used in part on other architectures to a small extent. Nevertheless, kunit_tool has not supported running tests on other architectures.
What this patchset does -----------------------
This patchset introduces first class support to kunit_tool for KUnit to be run on many popular architectures via QEMU. It does this by adding two new flags: `--arch` and `--cross_compile`.
`--arch` allows an architecture to be specified by the name the architecture is given in `arch/`. It uses the specified architecture to select a minimal amount of Kconfigs and QEMU configs needed for the architecture to run in QEMU and provide a console from which KTAP results can be scraped.
`--cross_compile` allows a toolchain prefix to be specified to make similar to how `CROSS_COMPILE` is used.
Additionally, this patchset revives the previously considered "kunit: tool: add support for QEMU"[1] patchs. The motivation for this new kernel command line flags, `kunit_shutdown`, is to better support running KUnit tests inside of QEMU. For most popular architectures, QEMU can be made to terminate when the Linux kernel that is being run is reboted, halted, or powered off. As Kees pointed out in a previous discussion[2], it is possible to make a kernel initrd that can reboot the kernel immediately, doing this for every architecture would likely be infeasible. Instead, just having an option for the kernel to shutdown when it is done with testing seems a lot simpler, especially since it is an option which would only available in testing configurations of the kernel anyway.
What discussion remains for this patchset? ------------------------------------------
The first most obvious thing is settling the debate about `kunit_shutdown`. If I recall correctly, Kees suggested that it might be better to just add a new initrd; however, as I mentioned above, now to support many new architectures, it may be substantially easier to support this option. So I am hoping with this new usecase, the argument for `kunit_shutdown` will be more compelling.
The second and likely harder issue is figuring out the best way to configure and provide configs for running KUnit tests via QEMU. I provide a pretty primitive way in this patchset which is not super flexible; for example, for our PPC support we have it set to build big endian, and POWER8 - we currently don't support a way to change that. Nevertheless, having sensible defaults is handy too, so we will probably want to have some support for overriding defaults, while still being able to have defaults.
[1] http://patches.linaro.org/patch/208336/ [2] https://lkml.org/lkml/2020/6/26/988
Brendan Higgins (3): Documentation: Add kunit_shutdown to kernel-parameters.txt kunit: tool: add support for QEMU Documentation: kunit: document support for QEMU in kunit_tool
David Gow (1): kunit: Add 'kunit_shutdown' option
.../admin-guide/kernel-parameters.txt | 8 + Documentation/dev-tools/kunit/usage.rst | 37 +++- lib/kunit/executor.c | 20 ++ tools/testing/kunit/kunit.py | 33 ++- tools/testing/kunit/kunit_config.py | 2 +- tools/testing/kunit/kunit_kernel.py | 209 +++++++++++++++--- tools/testing/kunit/kunit_parser.py | 2 +- tools/testing/kunit/kunit_tool_test.py | 15 +- 8 files changed, 278 insertions(+), 48 deletions(-)
base-commit: 7af08140979a6e7e12b78c93b8625c8d25b084e2