Re: linux-next: build failure after merge of the block tree

David Gow
2026-01-22T06:36:28Z

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On Thu, 22 Jan 2026 at 02:55, Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> On Wed, Jan 21, 2026 at 3:56 PM Mark Brown <broonie@kernel.org> wrote:

(...snnip...)

> > Running rusttest is a bit weird in that it requires a kernel config but
> > seems to work fine so I can do that, I was already planning to run KUnit:
>
> We used the `rusttest` target more in the past, before I made the
> KUnit integration of the doctests, but it really doesn't do much
> nowadays and carries a fair bit of complexity on the build system. My
> current thinking is to migrate those tests and then just make it no-op
> until we find a better use case if any for the target name. So it
> isn't critical if you don't run it.
>
> Now, you mention KUnit, and that is very interesting!
>
> The overwhelming majority of our tests are all in fact KUnit-based,
> e.g. these are our doctests (i.e. examples that are built and ran as
> tests):
>
> [ 2.714912] # rust_doctests_kernel: pass:283 fail:0 skip:0 total:283
>
> but we also have a few other suites that come from `#[test]`s
> ("normal" unit tests), e.g.:
>
> [ 2.260774] # rust_atomics: pass:6 fail:0 skip:0 total:6
>
> So, do you mean you plan to run them under QEMU for x86_64 or arm64 or
> similar? That would be amazing for us! I didn't know you planned to do
> runtime tests.
>
> For x86_64 and arm64 things should work fine and it would be great to
> enforce it in linux-next already (I check the KUnit results in several
> trees, including stable/LTSs).
>
> Now, if you mean UML to run them, that is still best-effort with Rust,
> and it may or may not be completely clean at certain moments (Cc'ing
> David, who has been driving that and done a ton of work there).

The UML Rust support is pretty stable for the core Rust bits, KUnit
tests, etc. It can get a little broken from time to time with new
drivers, gcc-based builds (instead of LLVM=1), or 32-bit builds.
Ideally, those will work as well --- everything seems fine at the
moment --- and you shouldn't have any problems with just running:

./tools/testing/kunit/kunit.py run --kconfig_add CONFIG_RUST=y
--make_options LLVM=1

But do let me know if anything is broken.

Cheers,
-- David

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