Starting with Rust 1.98.0 (expected 2026-08-20), the target spec will not
support `x86-softfloat` anymore [1]. Instead, `softfloat` should be used,
which is an alias. Otherwise, one gets:

    error: error loading target specification: rustc-abi: invalid rustc abi: 'x86-softfloat'. allowed values: 'x86-sse2', 'softfloat' at line 3 column 32
      |
      = help: run `rustc --print target-list` for a list of built-in targets

Thus conditionally use one or the other depending on the version.

The alias has existed since Rust 1.95.0 (released 2026-04-16) [2], but
use the newer version instead to avoid changing how the build works for
existing compilers, at least until more testing takes place.

Cc: Ralf Jung <post@ralfj.de>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: https://github.com/rust-lang/rust/pull/157151 [1]
Link: https://github.com/rust-lang/rust/pull/151154 [2]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 scripts/generate_rust_target.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs
index 38b3416bb979..02bc45d15484 100644
--- a/scripts/generate_rust_target.rs
+++ b/scripts/generate_rust_target.rs
@@ -196,7 +196,9 @@ fn main() {
         }
     } else if cfg.has("X86_64") {
         ts.push("arch", "x86_64");
-        if cfg.rustc_version_atleast(1, 86, 0) {
+        if cfg.rustc_version_atleast(1, 98, 0) {
+            ts.push("rustc-abi", "softfloat");
+        } else if cfg.rustc_version_atleast(1, 86, 0) {
             ts.push("rustc-abi", "x86-softfloat");
         }
         ts.push(

base-commit: ac35b5580ace12e5d0a0b5e61e36d2c4e1ffa29c
-- 
2.54.0

On Sat, May 30, 2026 at 1:49 PM Miguel Ojeda <ojeda@kernel.org> wrote:
>
> Starting with Rust 1.98.0 (expected 2026-08-20), the target spec will not
> support `x86-softfloat` anymore [1]. Instead, `softfloat` should be used,
> which is an alias. Otherwise, one gets:
>
>     error: error loading target specification: rustc-abi: invalid rustc abi: 'x86-softfloat'. allowed values: 'x86-sse2', 'softfloat' at line 3 column 32
>       |
>       = help: run `rustc --print target-list` for a list of built-in targets
>
> Thus conditionally use one or the other depending on the version.
>
> The alias has existed since Rust 1.95.0 (released 2026-04-16) [2], but
> use the newer version instead to avoid changing how the build works for
> existing compilers, at least until more testing takes place.
>
> Cc: Ralf Jung <post@ralfj.de>
> Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
> Link: https://github.com/rust-lang/rust/pull/157151 [1]
> Link: https://github.com/rust-lang/rust/pull/151154 [2]
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Applied to `rust-fixes` early so that we start getting testing
tomorrow -- thanks everyone!

Tags still welcome for a day or so.

(I considered `rust-next`, but to simplify testing for ~2 weeks for
those that want to use nightly, I decided to put it in `rust-fixes`
instead.)

Cheers,
Miguel

On Sat, May 30, 2026 at 1:49 PM Miguel Ojeda <ojeda@kernel.org> wrote:
>
> Starting with Rust 1.98.0 (expected 2026-08-20), the target spec will not
> support `x86-softfloat` anymore [1]. Instead, `softfloat` should be used,
> which is an alias. Otherwise, one gets:
>
>     error: error loading target specification: rustc-abi: invalid rustc abi: 'x86-softfloat'. allowed values: 'x86-sse2', 'softfloat' at line 3 column 32
>       |
>       = help: run `rustc --print target-list` for a list of built-in targets
>
> Thus conditionally use one or the other depending on the version.
>
> The alias has existed since Rust 1.95.0 (released 2026-04-16) [2], but
> use the newer version instead to avoid changing how the build works for
> existing compilers, at least until more testing takes place.
>
> Cc: Ralf Jung <post@ralfj.de>
> Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
> Link: https://github.com/rust-lang/rust/pull/157151 [1]
> Link: https://github.com/rust-lang/rust/pull/151154 [2]
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

With UML updated too:

Reviewed-by: Alice Ryhl <aliceryhl@google.com>

On Sat, May 30, 2026 at 1:49 PM Miguel Ojeda <ojeda@kernel.org> wrote:
>
>      } else if cfg.has("X86_64") {

And the same change for 32-bit UML as Sashiko points out, of course --
tested that one now too.

Cheers,
Miguel