Armv7 fixes

.github/workflows/smoke.yml

@@ -157,3 +157,45 @@ jobs:
         . $CONDA/etc/profile.d/conda.sh
         conda activate pyav
         python -m pytest
+
+  armv7:
+    name: "armv7 cross-build + qemu smoke"
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v6
+      - name: Set up host Python 3.11
+        uses: actions/setup-python@v6
+        with:
+          python-version: "3.11"
+      - name: Set up host Python 3.14t
+        uses: actions/setup-python@v6
+        with:
+          python-version: "3.14t"
+      - name: Install build tooling
+        run: |
+          for py in python3.11 python3.14t; do
+            $py -m pip install -U "cython>=3.1.0,<4" "setuptools>=77.0" wheel
+          done
+          # patchelf 0.18 (ubuntu-24.04's system version) corrupts ELF files
+          # with large p_align; pin <0.18 for auditwheel to use.
+          python3.11 -m pip install -U ziglang auditwheel 'patchelf<0.18'
+      - name: Cross-compile armv7l wheels with zig
+        env:
+          HOST_PY311: python3.11
+          HOST_PY314T: python3.14t
+          TOOLS_PY: python3.11
+        run: bash scripts/build-armv7l-cross.sh
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+        with:
+          platforms: arm
+      - name: Import-test wheels under emulation
+        run: |
+          docker run --rm --platform linux/arm/v7 -v "$PWD/dist:/dist:ro" \
+            quay.io/pypa/manylinux_2_31_armv7l bash -ceu '
+              for py in /opt/python/cp311-cp311 /opt/python/cp314-cp314t; do
+                echo "::group::$("$py/bin/python" --version)"
+                "$py/bin/pip" install --no-index --find-links /dist av
+                "$py/bin/python" -m av --version
+                echo "::endgroup::"
+              done'

.github/workflows/tests.yml

@@ -96,7 +96,9 @@ jobs:
           for py in python3.11 python3.14t; do
             $py -m pip install -U "cython>=3.1.0,<4" "setuptools>=77.0" wheel
           done
-          python3.11 -m pip install -U ziglang auditwheel
+          # patchelf 0.18 (ubuntu-24.04's system version) corrupts ELF files
+          # with large p_align; pin <0.18 for auditwheel to use.
+          python3.11 -m pip install -U ziglang auditwheel 'patchelf<0.18'
       - name: Cross-compile armv7l wheels with zig
         env:
           HOST_PY311: python3.11

scripts/build-armv7l-cross.sh

@@ -102,21 +102,31 @@ build_one() {
     rm -rf "$raw"; mkdir -p "$raw"
 
     # The _PYTHON_* vars make sysconfig report armv7l; zig does the compiling.
+    # max-page-size=4096 aligns our extensions to the armv7l (4K) page size;
+    # lld's default 64K alignment uses 4K file offsets, which the loader rejects.
+    # Setting CFLAGS replaces the target's default OPT flags, so -O2 -DNDEBUG
+    # must be passed explicitly (without NDEBUG the free-threaded build trips a
+    # Py_SET_REFCNT assertion that release wheels compile out).
     env \
         CC="$BIN_DIR/zig-cc" CXX="$BIN_DIR/zig-cxx" AR="$BIN_DIR/zig-ar" \
-        LDSHARED="$BIN_DIR/zig-cc -shared" \
+        LDSHARED="$BIN_DIR/zig-cc -shared -Wl,-z,max-page-size=4096" \
         _PYTHON_HOST_PLATFORM=linux-armv7l \
         _PYTHON_SYSCONFIGDATA_NAME="$(basename "${scd[0]}" .py)" \
         PYTHONPATH="$(dirname "${scd[0]}")" \
-        CFLAGS="-I${inc[0]} -Wno-error=incompatible-pointer-types" \
+        CFLAGS="-I${inc[0]} -O2 -DNDEBUG -Wno-error=incompatible-pointer-types" \
         PKG_CONFIG_PATH=/tmp/vendor/lib/pkgconfig \
         LD_LIBRARY_PATH=/tmp/vendor/lib \
         "$host_py" -m pip wheel . --no-build-isolation --no-deps -w "$raw"
 
     # Bundle FFmpeg + its armhf system deps and stamp the platform tag. The shim
     # lets auditwheel accept the armv7l --plat from an x86_64 host; --ldpaths
-    # points it at the target's libs instead of the host search path.
-    "$TOOLS_PY" scripts/auditwheel-cross.py armv7l glibc repair \
+    # points it at the target's libs instead of the host search path. Force the
+    # pip patchelf (<0.18, on PATH via the scripts dir) ahead of the system one:
+    # ubuntu-24.04 ships patchelf 0.18.0, which silently corrupts ELF files with
+    # large p_align, breaking the bundled FFmpeg libs at runtime.
+    local pe_dir
+    pe_dir="$("$TOOLS_PY" -c 'import sysconfig; print(sysconfig.get_path("scripts"))')"
+    PATH="$pe_dir:$PATH" "$TOOLS_PY" scripts/auditwheel-cross.py armv7l glibc repair \
         --ldpaths "/tmp/vendor/lib:$PY_DIR/syslib" \
         --plat "$PLAT" -w "$DIST_DIR" "$raw"/*.whl
 }