Add support for aarch64 musl

ci-targets.yaml

@@ -348,6 +348,26 @@ linux:
         minimum-python-version: "3.13"
     run: true
 
+  aarch64-unknown-linux-musl:
+    arch: aarch64
+    libc: musl
+    python_versions:
+      - "3.9"
+      - "3.10"
+      - "3.11"
+      - "3.12"
+      - "3.13"
+      - "3.14"
+    build_options:
+      # TODO: Static support is current blocked by some compiler-rt linking issues
+      # - debug+static
+      # - noopt+static
+      # - lto+static
+      - debug
+      - noopt
+      - lto
+    run: true
+
 windows:
   i686-pc-windows-msvc:
     arch: x86

cpython-unix/build-cpython.sh

@@ -1077,8 +1077,14 @@ touch "${LIB_DYNLOAD}/.empty"
 
 # Symlink libpython so we don't have 2 copies.
 case "${TARGET_TRIPLE}" in
-aarch64-unknown-linux-gnu)
-    PYTHON_ARCH="aarch64-linux-gnu"
+aarch64-unknown-linux-*)
+    # In Python 3.13+, the musl target is identified in cross compiles and the output directory
+    # is named accordingly.
+    if [[ "${CC}" = "musl-clang" && -n "${PYTHON_MEETS_MINIMUM_VERSION_3_13}" ]]; then
+        PYTHON_ARCH="aarch64-linux-musl"
+    else
+        PYTHON_ARCH="aarch64-linux-gnu"
+    fi
     ;;
 # This is too aggressive. But we don't have patches in place for
 # setting the platform name properly on non-Darwin.

cpython-unix/build.py

@@ -88,6 +88,11 @@ def add_target_env(env, build_platform, target_triple, build_env):
     extra_host_cflags = []
     extra_host_ldflags = []
 
+    # Add compiler-rt for aarch64-musl to resolve missing builtins
+    if target_triple == "aarch64-unknown-linux-musl":
+        extra_target_cflags.append("--rtlib=compiler-rt")
+        extra_target_ldflags.append("--rtlib=compiler-rt")
+
     if build_platform.startswith("linux_"):
         machine = platform.machine()
 

cpython-unix/targets.yml

@@ -1131,3 +1131,49 @@ x86_64_v4-unknown-linux-musl:
     - zlib
     - zstd
   openssl_target: linux-x86_64
+
+aarch64-unknown-linux-musl:
+  host_platforms:
+    - linux_x86_64
+    - linux_aarch64
+  pythons_supported:
+    - '3.9'
+    - '3.10'
+    - '3.11'
+    - '3.12'
+    - '3.13'
+    - '3.14'
+  needs_toolchain: true
+  docker_image_suffix: .debian9
+  needs_toolchain: true
+  host_cc: clang
+  host_cxx: clang++
+  target_cc: musl-clang
+  target_cxx: clang++
+  target_cflags:
+    - '-fvisibility=hidden'
+  needs:
+    - autoconf
+    - bdb
+    - binutils
+    - bzip2
+    - expat
+    - libedit
+    - libffi-3.3
+    - libX11
+    - libXau
+    - libxcb
+    - m4
+    - mpdecimal
+    - musl
+    - ncurses
+    - openssl-3.0
+    - patchelf
+    - sqlite
+    - tcl
+    - tk
+    - uuid
+    - xorgproto
+    - xz
+    - zlib
+  openssl_target: linux-aarch64

src/validation.rs

@@ -35,6 +35,7 @@ const RECOGNIZED_TRIPLES: &[&str] = &[
     "aarch64-apple-ios",
     "aarch64-pc-windows-msvc",
     "aarch64-unknown-linux-gnu",
+    "aarch64-unknown-linux-musl",
     "armv7-unknown-linux-gnueabi",
     "armv7-unknown-linux-gnueabihf",
     "arm64-apple-tvos",
@@ -157,6 +158,10 @@ static GLIBC_MAX_VERSION_BY_TRIPLE: Lazy<HashMap<&'static str, version_compare::
             "aarch64-unknown-linux-gnu",
             version_compare::Version::from("2.17").unwrap(),
         );
+        versions.insert(
+            "aarch64-unknown-linux-musl",
+            version_compare::Version::from("1").unwrap(),
+        );
         versions.insert(
             "armv7-unknown-linux-gnueabi",
             version_compare::Version::from("2.17").unwrap(),
@@ -549,6 +554,7 @@ static PLATFORM_TAG_BY_TRIPLE: Lazy<HashMap<&'static str, &'static str>> = Lazy:
         ("aarch64-apple-ios", "iOS-aarch64"),
         ("aarch64-pc-windows-msvc", "win-arm64"),
         ("aarch64-unknown-linux-gnu", "linux-aarch64"),
+        ("aarch64-unknown-linux-musl", "linux-aarch64"),
         ("armv7-unknown-linux-gnueabi", "linux-arm"),
         ("armv7-unknown-linux-gnueabihf", "linux-arm"),
         ("i686-pc-windows-msvc", "win32"),
@@ -949,6 +955,7 @@ fn validate_elf<Elf: FileHeader<Endian = Endianness>>(
 
     let wanted_cpu_type = match target_triple {
         "aarch64-unknown-linux-gnu" => object::elf::EM_AARCH64,
+        "aarch64-unknown-linux-musl" => object::elf::EM_AARCH64,
         "armv7-unknown-linux-gnueabi" => object::elf::EM_ARM,
         "armv7-unknown-linux-gnueabihf" => object::elf::EM_ARM,
         "i686-unknown-linux-gnu" => object::elf::EM_386,