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rust: x86: support Rust >= 1.98.0 target spec

PATCH In review Miguel Ojeda 3 participants 4 messages May 30 – May 31

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Miguel Ojeda

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#0 lore raw

PATCH 1/1 rust: x86: support Rust >= 1.98.0 target spec

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 <[email protected]>
Cc [email protected] # 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 <[email protected]>
---
 scripts/generate_rust_target.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
scripts/generate_rust_target.rs +3 -1
index 38b3416bb979..02bc45d15484 100644
@@ -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

Signature · 1 line
2.54.0
#1 lore raw
Quoted 2 lines · Miguel Ojeda
     } 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

reviewer Reviewed-by on v1 1/1
#2 lore raw
In reply to Miguel Ojeda
Quoted 15 lines · Miguel Ojeda

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.

Quoted 5 lines
Cc Ralf Jung <[email protected]>
Cc [email protected] # 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 <[email protected]>

With UML updated too:

Reviewed-by Alice Ryhl <[email protected]>
#3 lore raw
In reply to Miguel Ojeda
Quoted 15 lines · Miguel Ojeda

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.

Quoted 5 lines
Cc Ralf Jung <[email protected]>
Cc [email protected] # 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 <[email protected]>

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