[RFC 00/10] drm: selftests: Convert to KUnit

[Daniel Latypov]

On Thu, Jan 20, 2022 at 2:21 PM Michał Winiarski
<michal.winiarski at intel.com> wrote:
> > So I'm a bit doubtful about this particular statement, but if you have
> > tried it out and it works well, then that's good too.
> >
> > I just think the primary benefit of UML is faster compilation and it
> > being somewhat lighter than bringing up a VM.
>
> It was good enough to debug any problems that I accidentally introduced
> during the conversion, but perhaps that was simple enough usecase to not
> encounter SIGSEGVs.

Ah, that's good to know.

>
> I don't thing that would work. IIUC, currently the runner is operating
> on taint - there's a subset of taints that it considers "fatal"
> (including TAINT_WARN).
>
> If we have tests that WARN, perhaps we could introduce extra flag to the
> test state on per-test or per-testsuite level, to mark that the test
> wants to fail-on-warn?
> Then we would only fail if the test opted in (or other way around? if
> opt-out makes more sense and we have more tests that actually don't WARN
> as part of their normal test logic).

Yeah, I think this would work.
I chatted with Brendan and David about this and suggested this approach.

This definitely seems useful, so I definitely think we should keep it
in mind, even if we don't get an implementation done in the near
future.

>
> It's applied on top of DRM subsystem integration tree (drm-tip):
> https://cgit.freedesktop.org/drm-tip
> At that time it was already based on v5.16.

Ack, thanks!

I might take another stab at applying the patches locally, but based
on my brief skim over them, everything seemed fine from a KUnit point
of view. It's quite clear you've read over KUnit pretty thoroughly
(e.g. figured out how to create new managed resources, etc.). So I
probably won't have any feedback to give.

>
> Most of that 17-18s is taken by two subtest of drm_mm_tests:
>
> [22:17:19] ============================================================
> [22:17:19] ================= drm_mm_tests (1 subtest) =================
> [22:17:27] [PASSED] test_insert
> [22:17:27] ================== [PASSED] drm_mm_tests ===================
> [22:17:27] ============================================================
> [22:17:27] Testing complete. Passed: 1, Failed: 0, Crashed: 0, Skipped:
> 0, Errors: 0
> [22:17:27] Elapsed time: 10.400s total, 0.001s configuring, 2.419s
> building, 7.947s running
>
> [22:17:42] ============================================================
> [22:17:42] ================= drm_mm_tests (1 subtest) =================
> [22:17:50] [PASSED] test_replace
> [22:17:50] ================== [PASSED] drm_mm_tests ===================
> [22:17:50] ============================================================
> [22:17:50] Testing complete. Passed: 1, Failed: 0, Crashed: 0, Skipped:
> 0, Errors: 0
> [22:17:50] Elapsed time: 10.272s total, 0.001s configuring, 2.492s
> building, 7.776s running
>
> Their runtime can be controlled with max_prime and max_iterations
> modparams - I left the default values intact, but we can tweak them to
> speed things up if needed.

Ah, I was not concerned about test runtime at all.
I was just suggesting that real-time output would be useful if you
didn't have it already.