Fix hard and soft float libc detection for managed Python distributions on ARM (#8498)

crates/uv-python/Cargo.toml

@@ -57,6 +57,9 @@ tracing = { workspace = true }
 url = { workspace = true }
 which = { workspace = true }
 
+[target.'cfg(target_os = "linux")'.dependencies]
+procfs = { workspace = true }
+
 [target.'cfg(target_os = "windows")'.dependencies]
 windows-sys = { workspace = true }
 windows-registry = { workspace = true }

crates/uv-python/src/cpuinfo.rs

@@ -0,0 +1,33 @@
+//! Fetches CPU information.
+
+use anyhow::Error;
+
+#[cfg(target_os = "linux")]
+use procfs::{CpuInfo, Current};
+
+/// Detects whether the hardware supports floating-point operations using ARM's Vector Floating Point (VFP) hardware.
+///
+/// This function is relevant specifically for ARM architectures, where the presence of the "vfp" flag in `/proc/cpuinfo`
+/// indicates that the CPU supports hardware floating-point operations.
+/// This helps determine whether the system is using the `gnueabihf` (hard-float) ABI or `gnueabi` (soft-float) ABI.
+///
+/// More information on this can be found in the [Debian ARM Hard Float Port documentation](https://wiki.debian.org/ArmHardFloatPort#VFP).
+#[cfg(target_os = "linux")]
+pub(crate) fn detect_hardware_floating_point_support() -> Result<bool, Error> {
+    let cpu_info = CpuInfo::current()?;
+    if let Some(features) = cpu_info.fields.get("Features") {
+        if features.contains("vfp") {
+            return Ok(true); // "vfp" found: hard-float (gnueabihf) detected
+        }
+    }
+
+    Ok(false) // Default to soft-float (gnueabi) if no "vfp" flag is found
+}
+
+/// For non-Linux systems or architectures, the function will return `false` as hardware floating-point detection
+/// is not applicable outside of Linux ARM architectures.
+#[cfg(not(target_os = "linux"))]
+#[allow(clippy::unnecessary_wraps)]
+pub(crate) fn detect_hardware_floating_point_support() -> Result<bool, Error> {
+    Ok(false) // Non-Linux or non-ARM systems: hardware floating-point detection is not applicable
+}

crates/uv-python/src/lib.rs

@@ -21,6 +21,7 @@ pub use crate::version_files::{
 };
 pub use crate::virtualenv::{Error as VirtualEnvError, PyVenvConfiguration, VirtualEnvironment};
 
+mod cpuinfo;
 mod discovery;
 pub mod downloads;
 mod environment;

crates/uv-python/src/platform.rs

@@ -1,3 +1,4 @@
+use crate::cpuinfo::detect_hardware_floating_point_support;
 use crate::libc::{detect_linux_libc, LibcDetectionError, LibcVersion};
 use std::fmt::Display;
 use std::ops::Deref;
@@ -30,7 +31,17 @@ impl Libc {
     pub(crate) fn from_env() -> Result<Self, LibcDetectionError> {
         match std::env::consts::OS {
             "linux" => Ok(Self::Some(match detect_linux_libc()? {
-                LibcVersion::Manylinux { .. } => target_lexicon::Environment::Gnu,
+                LibcVersion::Manylinux { .. } => match std::env::consts::ARCH {
+                    // Checks if the CPU supports hardware floating-point operations.
+                    // Depending on the result, it selects either the `gnueabihf` (hard-float) or `gnueabi` (soft-float) environment.
+                    // download-metadata.json only includes armv7.
+                    "arm" | "armv7" => match detect_hardware_floating_point_support() {
+                        Ok(true) => target_lexicon::Environment::Gnueabihf,
+                        Ok(false) => target_lexicon::Environment::Gnueabi,
+                        Err(_) => target_lexicon::Environment::Gnu,
+                    },
+                    _ => target_lexicon::Environment::Gnu,
+                },
                 LibcVersion::Musllinux { .. } => target_lexicon::Environment::Musl,
             })),
             "windows" | "macos" => Ok(Self::None),