KUnit issues - Was: [igt-dev] [PATCH RFC v2 8/8] drm/i915: check if current->mm is not NULL

[Michał Winiarski]

On Thu, Nov 03, 2022 at 04:23:02PM +0100, Mauro Carvalho Chehab wrote:
> Hi,
> 
> I'm facing a couple of issues when testing KUnit with the i915 driver.
> 
> The DRM subsystem and the i915 driver has, for a long time, his own
> way to do unit tests, which seems to be added before KUnit.
> 
> I'm now checking if it is worth start using KUnit at i915. So, I wrote
> a RFC with some patches adding support for the tests we have to be
> reported using Kernel TAP and KUnit.
> 
> There are basically 3 groups of tests there:
> 
> - mock tests - check i915 hardware-independent logic;
> - live tests - run some hardware-specific tests;
> - perf tests - check perf support - also hardware-dependent.
> 
> As they depend on i915 driver, they run only on x86, with PCI
> stack enabled, but the mock tests run nicely via qemu.
> 
> The live and perf tests require a real hardware. As we run them
> together with our CI, which, among other things, test module
> unload/reload and test loading i915 driver with different
> modprobe parameters, the KUnit tests should be able to run as
> a module.

Note that KUnit tests that are doing more of a functional/integration
testing (on "live" hardware) rather than unit testing (where hardware
interactions are mocked) are not very common.
Do we have other KUnit tests like this merged?
Some of the "live tests" are not even that, being more of a pure
hardware tests (e.g. live_workarounds, which is checking whether values
in MMIO regs stick over various HW state transitions).

I'm wondering, is KUnit the right tool for this job?

-Michał