[FEA]: Add per-library path override env var to cuda.pathfinder#1979
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rparolin wants to merge 2 commits intoNVIDIA:mainfrom
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[FEA]: Add per-library path override env var to cuda.pathfinder#1979rparolin wants to merge 2 commits intoNVIDIA:mainfrom
rparolin wants to merge 2 commits intoNVIDIA:mainfrom
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Adds CUDA_PATHFINDER_<LIBNAME_UPPER>_PATH_OVERRIDE as a developer escape hatch for pointing cuda.pathfinder at a custom build of a specific library (e.g. a development branch of nvshmem) without having to remove the wheel or copy .so files into site-packages. The value can be either an absolute file path (used as-is) or a directory (searched with the same platform logic as conda / CUDA_PATH). The override has the highest priority and applies uniformly to CTK, third-party, and driver libraries. If the env var is set but the library cannot be resolved from it, the load fails immediately rather than silently falling through to other search steps. This keeps the override behavior explicit and easy to debug. Closes NVIDIA#1054. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
rparolin
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Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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rwgk
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Apr 27, 2026
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| 0. **Already loaded in the current process** |
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I'm almost certain we have to keep this first.
0. **Already loaded in the current process**
Otherwise we could have undefined behavior. It's a while ago that I looked into the details of this. If there are strong reasons, I could try to dig into this question again, but I hope it's acceptable to keep it first.
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Closing b/c we are going to merge this functionality into another set of work. |
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Summary
Closes #1054.
Adds
CUDA_PATHFINDER_<LIBNAME_UPPER>_PATH_OVERRIDEas a developer escape hatch so users working on a development branch of a library (e.g. nvshmem) can pointcuda.pathfinderat a custom build without having to uninstall the wheel or copy.sofiles intosite-packages.This implements option 1 from the issue (per-library override), which matches @kkraus14's later suggestion in the thread for a per-library, pathfinder-specific knob — and avoids the cross-cutting precedence concerns @leofang raised against a global
TOP_PRIORITY_PATH.Behavior
CUDA_PATHFINDER_<LIBNAME_UPPER>_PATH_OVERRIDEnvshmem_host→CUDA_PATHFINDER_NVSHMEM_HOST_PATH_OVERRIDEcublasLt→CUDA_PATHFINDER_CUBLASLT_PATH_OVERRIDECUDA_PATH).CUDA_PATH, and the canary probe. Applies uniformly to CTK, third-party, and driver libraries.DynamicLibNotFoundErrorimmediately rather than silently falling through. Silent fallthrough would be the actual debugging footgun — a typo or stale path should be loud.found_via: tagged asoverride(CUDA_PATHFINDER_<LIB>_PATH_OVERRIDE)so the resolved source is distinguishable fromsite-packages,conda, etc.Files
cuda_pathfinder/cuda/pathfinder/_dynamic_libs/search_steps.py— newfind_via_path_overridefind step +path_override_env_varhelper; prepended toEARLY_FIND_STEPS.cuda_pathfinder/cuda/pathfinder/_dynamic_libs/load_nvidia_dynamic_lib.py— driver fast-path also honors the override; updated docstring.cuda_pathfinder/tests/test_search_steps.py— 11 new unit tests.🤖 Generated with Claude Code