Add metal::set_metallib_path() to override the metallib search path#3597
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olilarkin wants to merge 1 commit into
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Add metal::set_metallib_path() to override the metallib search path#3597olilarkin wants to merge 1 commit into
olilarkin wants to merge 1 commit into
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Allows overriding the default metallib search paths before Device initialization. Needed when MLX is embedded in plugin bundles (AU, VST3) where the standard search locations don't apply.
zcbenz
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May 28, 2026
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I think this is a good API to have, better than adding numerous fallbacks for searching. But I would like another review from maintainers before merging.
| static std::string g_metallib_override_path; | ||
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| namespace mlx::core::metal { | ||
| void set_metallib_path(const std::string& path) { |
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Can you move this to mlx/backend/metal/metal.cpp, and add a stub in mlx/backend/metal/no_metal.cpp? Probably also needs to add a get_metallib_path.
| namespace mlx::core::metal { | ||
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| } // namespace std | ||
| static std::string g_metallib_override_path; |
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The globals are usually put in anonymous namespace rather than using static.
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What
Adds
mlx::core::metal::set_metallib_path(const std::string&), allowing a caller to specify an explicit path tomlx.metallibbefore the Metal device initializes. When set,load_default_library()tries this path first and falls back to the existing search logic if it fails to load.Why
When MLX is embedded inside a plugin bundle (e.g. Audio Unit / VST3), the host application — not MLX — owns the main bundle, so the default colocated / SwiftPM / bundle search paths don't resolve
mlx.metalliband Metal init fails. There is currently no public way to point MLX at the library.Notes
Companion PRs
This is the root of a three-PR chain (C++ → C → Swift):
set_metallib_path)GPU.setMetallibPath()Tracking issue: ml-explore/mlx-swift#415.