[PATCH v2] Fail the build on RUST=y and RUST_IS_AVAILABLE=n

[PATCH v2] Fail the build on RUST=y and RUST_IS_AVAILABLE=n

[Sasha Finkelstein]

The current approach of silently disabling all rust drivers if the
toolchain is missing results in users that try to compile their own
kernels getting a "successful" build and then being confused about where
did their drivers go. In comparison, missing openssl results in a build
failure, not a disappearance of everything that depends on it.

This also means that allyesconfig will depend on rust, but since the
rust experiment concluded with "rust is here to stay", i believe that
allyesconfig should be building rust drivers too.

Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>
---
Changes in v2:
- No longer a RFC, let's make it happen.
- Update the docs.
- Link to v1: https://patch.msgid.link/20260510-evolve-to-crab-v1-1-208df84e67be@chaosmail.tech
---
 Documentation/rust/quick-start.rst | 6 +++---
 init/Kconfig                       | 1 -
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/Documentation/rust/quick-start.rst b/Documentation/rust/quick-start.rst
index a6ec3fa94d33..764c81d0dd59 100644
--- a/Documentation/rust/quick-start.rst
+++ b/Documentation/rust/quick-start.rst
@@ -321,9 +321,9 @@ Configuration
 -------------
 
 ``Rust support`` (``CONFIG_RUST``) needs to be enabled in the ``General setup``
-menu. The option is only shown if a suitable Rust toolchain is found (see
-above), as long as the other requirements are met. In turn, this will make
-visible the rest of options that depend on Rust.
+menu. In turn, this will make visible the rest of options that depend on Rust.
+You can check the value of ``RUST_IS_AVAILABLE`` to determine if your toolchain
+is configured correctly.
 
 Afterwards, go to::
 
diff --git a/init/Kconfig b/init/Kconfig
index 2937c4d308ae..f7d4c7ea764f 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -2190,7 +2190,6 @@ config PROFILING
 config RUST
 	bool "Rust support"
 	depends on HAVE_RUST
-	depends on RUST_IS_AVAILABLE
 	select EXTENDED_MODVERSIONS if MODVERSIONS
 	depends on !MODVERSIONS || GENDWARFKSYMS
 	depends on !GCC_PLUGIN_RANDSTRUCT

---
base-commit: 8bc67e4db64aa72732c474b44ea8622062c903f0
change-id: 20260510-evolve-to-crab-8cba1768dcd5

Best regards,
--  
Sasha Finkelstein <k@chaosmail.tech>

Re: [PATCH v2] Fail the build on RUST=y and RUST_IS_AVAILABLE=n

[Neal Gompa]

On Thu, May 21, 2026 at 4:32 AM Sasha Finkelstein <k@chaosmail.tech> wrote:
>
> The current approach of silently disabling all rust drivers if the
> toolchain is missing results in users that try to compile their own
> kernels getting a "successful" build and then being confused about where
> did their drivers go. In comparison, missing openssl results in a build
> failure, not a disappearance of everything that depends on it.
>
> This also means that allyesconfig will depend on rust, but since the
> rust experiment concluded with "rust is here to stay", i believe that
> allyesconfig should be building rust drivers too.
>
> Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>
> ---
> Changes in v2:
> - No longer a RFC, let's make it happen.
> - Update the docs.
> - Link to v1: https://patch.msgid.link/20260510-evolve-to-crab-v1-1-208df84e67be@chaosmail.tech
> ---
>  Documentation/rust/quick-start.rst | 6 +++---
>  init/Kconfig                       | 1 -
>  2 files changed, 3 insertions(+), 4 deletions(-)
>

At this point, yes, we should just go ahead and do this.

Reviewed-by: Neal Gompa <neal@gompa.dev>


-- 
真実はいつも一つ！/ Always, there's only one truth!

Re: [PATCH v2] Fail the build on RUST=y and RUST_IS_AVAILABLE=n

[Andreas Hindborg]

"Sasha Finkelstein" <k@chaosmail.tech> writes:

> The current approach of silently disabling all rust drivers if the
> toolchain is missing results in users that try to compile their own
> kernels getting a "successful" build and then being confused about where
> did their drivers go. In comparison, missing openssl results in a build
> failure, not a disappearance of everything that depends on it.
>
> This also means that allyesconfig will depend on rust, but since the
> rust experiment concluded with "rust is here to stay", i believe that
> allyesconfig should be building rust drivers too.
>
> Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

This is long overdue.

Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>

Best regards,
Andreas Hindborg

Re: [PATCH v2] Fail the build on RUST=y and RUST_IS_AVAILABLE=n

[Gary Guo]

On Thu May 21, 2026 at 9:30 AM BST, Sasha Finkelstein wrote:
> The current approach of silently disabling all rust drivers if the
> toolchain is missing results in users that try to compile their own
> kernels getting a "successful" build and then being confused about where
> did their drivers go. In comparison, missing openssl results in a build
> failure, not a disappearance of everything that depends on it.
> 
> This also means that allyesconfig will depend on rust, but since the
> rust experiment concluded with "rust is here to stay", i believe that
> allyesconfig should be building rust drivers too.
> 
> Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>

Reviewed-by: Gary Guo <gary@garyguo.net>

> ---
> Changes in v2:
> - No longer a RFC, let's make it happen.
> - Update the docs.
> - Link to v1: https://patch.msgid.link/20260510-evolve-to-crab-v1-1-208df84e67be@chaosmail.tech
> ---
>  Documentation/rust/quick-start.rst | 6 +++---
>  init/Kconfig                       | 1 -
>  2 files changed, 3 insertions(+), 4 deletions(-)