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fix(build): update CUDA linking strategy for Windows. #759

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Merged
MarcusDunn merged 1 commit into from
Jun 20, 2025
Merged

fix(build): update CUDA linking strategy for Windows. #759

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38 changes: 27 additions & 11 deletions llama-cpp-sys-2/build.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -398,28 +398,44 @@ fn main() {
println!("cargo:rustc-link-search={}", build_dir.display());

if cfg!(feature = "cuda") && !build_shared_libs {
// Re-run build script if CUDA_PATH environment variable changes
println!("cargo:rerun-if-env-changed=CUDA_PATH");

// Add CUDA library directories to the linker search path
for lib_dir in find_cuda_helper::find_cuda_lib_dirs() {
println!("cargo:rustc-link-search=native={}", lib_dir.display());
}

// Logic from ggml-cuda/CMakeLists.txt
println!("cargo:rustc-link-lib=static=cudart_static");
if matches!(target_os, TargetOs::Windows(_)) {
println!("cargo:rustc-link-lib=static=cublas");
println!("cargo:rustc-link-lib=static=cublasLt");
// Platform-specific linking
if cfg!(target_os = "windows") {
// ✅ On Windows, use dynamic linking.
// Static linking is problematic because NVIDIA does not provide culibos.lib,
// and static CUDA libraries (like cublas_static.lib) are usually not shipped.

println!("cargo:rustc-link-lib=cudart"); // Links to cudart64_*.dll
println!("cargo:rustc-link-lib=cublas"); // Links to cublas64_*.dll
println!("cargo:rustc-link-lib=cublasLt"); // Links to cublasLt64_*.dll

// Link to CUDA driver API (nvcuda.dll via cuda.lib)
if !cfg!(feature = "cuda-no-vmm") {
println!("cargo:rustc-link-lib=cuda");
}
} else {
// ✅ On non-Windows platforms (e.g., Linux), static linking is preferred and supported.
// Static libraries like cudart_static and cublas_static depend on culibos.

println!("cargo:rustc-link-lib=static=cudart_static");
println!("cargo:rustc-link-lib=static=cublas_static");
println!("cargo:rustc-link-lib=static=cublasLt_static");
}

// Need to link against libcuda.so unless GGML_CUDA_NO_VMM is defined.
if !cfg!(feature = "cuda-no-vmm") {
println!("cargo:rustc-link-lib=cuda");
}
// Link to CUDA driver API (libcuda.so)
if !cfg!(feature = "cuda-no-vmm") {
println!("cargo:rustc-link-lib=cuda");
}

println!("cargo:rustc-link-lib=static=culibos");
// culibos is required when statically linking cudart_static
println!("cargo:rustc-link-lib=static=culibos");
}
}

// Link libraries
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