Re: [PATCH v2] hardening: Default randstruct off with rust for better allmodconfig support

[Kees Cook <kees@kernel.org>]

On Fri, Jun 05, 2026 at 07:22:54PM +0200, Miguel Ojeda wrote:
> On Fri, Jun 5, 2026 at 6:51 PM Mark Brown <broonie@kernel.org> wrote:
> >
> > Currently randstruct does not support rust so we have Kconfig dependencies
> > which prevent rust being enabled when randstruct is. Unfortunately this
> > prevents rust being enabled in allmodconfig, our standard coverage build.
> > randstruct gets turned on by default, then the dependency on !RANDSTRUCT
> > causes rust to get disabled.
> >
> > Work around this by disabling randstruct by default if we have a usable
> > rust toolchain and rust support for the architecture, circular
> > dependencies prevent us directly depending on !RUST. This means we might
> > end up with a configuration that disables both rust and randstruct but
> > hopefully it's more likely go give the expected result.
> >
> > Signed-off-by: Mark Brown <broonie@kernel.org>
> 
> Thanks Mark!
> 
> Kees, Gustavo: applying this would help Mark's testing of Rust in
> linux-next, which is important to keep.
> 
> An alternative would be to move forward with `RANDSTRUCT` support:
> 
>   https://lore.kernel.org/rust-for-linux/20260323130224.165738-1-ojeda@kernel.org/
> 
> Either the conditional (on the Rust side) or the unconditional
> approaches (modifying the C side) should be fine, i.e. whatever
> Kees/Gustavo think is best. The unconditional one would make things
> easier on the Rust side, but it is a "bigger" change in terms of
> impact. We can always start with the conditional one instead.

Oops, I missed this v2. :)

For the linux-next testing, are you doing GCC + llvm rustc builds? IIUC,
then the support patch mentioned, I think, doesn't actually solve the
problem?

-Kees

-- 
Kees Cook