test: skip CUDA-GL interop tests when the GL context is not on an NVIDIA GPU

cuda_bindings/tests/test_graphics_apis.py

@@ -9,7 +9,11 @@
 
 import pyglet
 import pytest
-from cuda_python_test_helpers.graphics import is_gl_context_unavailable, open_gl_window
+from cuda_python_test_helpers.graphics import (
+    gl_context_not_on_nvidia_gpu_reason,
+    is_gl_context_unavailable,
+    open_gl_window,
+)
 
 from cuda.bindings import runtime as cudart
 
@@ -63,6 +67,8 @@ def _gl_context():
 
     tex_id = None
     try:
+        if reason := gl_context_not_on_nvidia_gpu_reason():
+            pytest.skip(reason)
         tex_id, target = _allocate_gl_texture(win)
         yield int(tex_id.value), int(target)
     finally:

cuda_core/tests/test_graphics.py

@@ -13,6 +13,7 @@
 import pyglet
 import pytest
 from cuda_python_test_helpers.graphics import (
+    gl_context_not_on_nvidia_gpu_reason,
     is_gl_context_unavailable,
     open_gl_window,
     select_headless_egl_device_for_cuda,
@@ -130,6 +131,8 @@ def _gl_context_and_buffer(nbytes=1024):
 
     buf_id = None
     try:
+        if reason := gl_context_not_on_nvidia_gpu_reason():
+            pytest.skip(reason)
         buf_id = _allocate_gl_buffer(win, nbytes)
         yield int(buf_id.value), nbytes
     finally:
@@ -158,6 +161,8 @@ def _gl_context_and_texture(width=16, height=16):
 
     tex_id = None
     try:
+        if reason := gl_context_not_on_nvidia_gpu_reason():
+            pytest.skip(reason)
         tex_id, target = _allocate_gl_texture(win, width, height)
         yield int(tex_id.value), int(target)
     finally:

cuda_core/tests/test_helpers.py

@@ -2,6 +2,7 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
+import ctypes
 import sys
 import time
 import types
@@ -360,7 +361,11 @@ def test_oom_diagnostics_probe_basics_is_live_and_cheap(init_cuda):
 # ---------------------------------------------------------------------------
 
 import pytest
-from cuda_python_test_helpers.graphics import is_gl_context_unavailable, open_gl_window
+from cuda_python_test_helpers.graphics import (
+    gl_context_not_on_nvidia_gpu_reason,
+    is_gl_context_unavailable,
+    open_gl_window,
+)
 
 
 @pytest.mark.thread_unsafe(reason="patches the process-wide pyglet module")
@@ -437,3 +442,28 @@ def test_is_gl_context_unavailable_accepts_genuine(exc):
 )
 def test_is_gl_context_unavailable_rejects_unrelated(exc):
     assert is_gl_context_unavailable(exc) is False
+
+
+def _patch_gl_vendor(monkeypatch, vendor):
+    # Only GL_VENDOR is answered; any other query (e.g. GL_RENDERER) returns NULL.
+    gl = types.SimpleNamespace(
+        GL_VENDOR=1,
+        GL_RENDERER=2,
+        glGetString=lambda name: ctypes.c_char_p(vendor if name == 1 else None),
+    )
+    monkeypatch.setitem(sys.modules, "pyglet.gl", types.SimpleNamespace(gl=gl))
+
+
+@pytest.mark.thread_unsafe(reason="patches the process-wide pyglet.gl module")
+def test_gl_context_not_on_nvidia_gpu_reason_accepts_nvidia(monkeypatch):
+    _patch_gl_vendor(monkeypatch, b"NVIDIA Corporation")
+    assert gl_context_not_on_nvidia_gpu_reason() is None
+
+
+@pytest.mark.thread_unsafe(reason="patches the process-wide pyglet.gl module")
+@pytest.mark.parametrize("vendor", [b"AMD", b"Mesa", None])
+def test_gl_context_not_on_nvidia_gpu_reason_rejects_other_vendors(monkeypatch, vendor):
+    _patch_gl_vendor(monkeypatch, vendor)
+    reason = gl_context_not_on_nvidia_gpu_reason()
+    assert reason is not None
+    assert "not on an NVIDIA GPU" in reason

cuda_python_test_helpers/cuda_python_test_helpers/graphics.py

@@ -110,6 +110,31 @@ def open_gl_window():
     return None
 
 
+def gl_context_not_on_nvidia_gpu_reason() -> str | None:
+    """Return a skip reason if the current GL context is not on an NVIDIA GPU, else None.
+
+    CUDA-GL interop requires the GL context to be rendered by an NVIDIA GPU.
+    When the context is created on a GPU from another vendor (e.g. on
+    multi-vendor GPU systems), `cuGraphicsGLRegister*` fails with
+    `CUDA_ERROR_UNKNOWN`, which is indistinguishable from a real failure at
+    the call site. Caller must have a current GL context.
+    """
+    from pyglet.gl import gl
+
+    def _get_string(name):
+        value = gl.glGetString(name)
+        return ctypes.cast(value, ctypes.c_char_p).value.decode(errors="replace") if value else ""
+
+    vendor = _get_string(gl.GL_VENDOR)
+    if "NVIDIA" in vendor:
+        return None
+    renderer = _get_string(gl.GL_RENDERER)
+    return (
+        f"GL context is not on an NVIDIA GPU (GL_VENDOR={vendor!r}, GL_RENDERER={renderer!r}); "
+        "CUDA-GL interop requires one."
+    )
+
+
 _GL_CONTEXT_UNAVAILABLE_EXC_NAMES = frozenset(
     {
         "NoSuchDisplayException",