Re: [PATCH] selftests/rseq: Add config fragment

[Mark Rutland <mark.rutland@arm.com>]

On Fri, Apr 24, 2026 at 12:16:22AM +0100, Mark Brown wrote:
> Currently we do not provide a config fragment for the rseq selftests but
> there are several options which are either required or helpful for
> running them:
> 
>  - CONFIG_RSEQ is required for obvious reasons, it is enabled by default
>    but it doesn't hurt to specify it in case the user is usinsg a
>    defconfig that disables it.
> 
>  - CONFIG_RSEQ_DEBUG_DEFAULT_ENABLE turns on runtime debug checks which
>    would for example have helped spot some of the recent issues we've
>    seen on arm64:
> 
>       https://lore.kernel.org/all/87zf2u28d1.ffs@tglx/
> 
>  - CONFIG_DEBUG_RSEQ enables debugging on configurations that don't have
>    generic entry support.
> 
>  - CONFIG_RSEQ_SLICE_EXTENSION is tested by the slice_test test, the
>    test will fail without it.
> 
> Add a configuration fragment which enables these options, helping
> encourage CI systems and people doing manual testing to run the tests
> with all the features and additional checks.  We also enable
> CONFIG_DEBUG_KERNEL and CONFIG_EXPERT which are dependencies for these
> options.

As a heads-up, it might be worth waiting on the DEBUG bits for now given
Linus's comment at:

  https://lore.kernel.org/linux-arm-kernel/CAHk-=wjsEqWJxXArS-P5+ksSY2Apaox8u6FtUrtyWSBEOL4Q2Q@mail.gmail.com/

i.e.

| (a) the debug code in question needs to just be removed, since it's
| now actively detrimental, and means that any kernel developer who
| *does* enable it can't actually test this case any more. It's checking
| for something that has been shown to not be true.

... but it probably makes sense to enable the SLICE_EXTENSION option if
we have tests for that.

Mark.

> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
>  tools/testing/selftests/rseq/config | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/tools/testing/selftests/rseq/config b/tools/testing/selftests/rseq/config
> new file mode 100644
> index 000000000000..d11b8c61530e
> --- /dev/null
> +++ b/tools/testing/selftests/rseq/config
> @@ -0,0 +1,6 @@
> +CONFIG_DEBUG_KERNEL=y
> +CONFIG_DEBUG_RSEQ=y
> +CONFIG_EXPERT=y
> +CONFIG_RSEQ=y
> +CONFIG_RSEQ_DEBUG_DEFAULT_ENABLE=y
> +CONFIG_RSEQ_SLICE_EXTENSION=y
> 
> ---
> base-commit: 2e68039281932e6dc37718a1ea7cbb8e2cda42e6
> change-id: 20260423-selftests-rseq-config-fragment-65f09caf0276
> 
> Best regards,
> --  
> Mark Brown <broonie@kernel.org>
>