cuda : do not create buffer types for devices that don't exist (fixes usage without CUDA devices available)

Author: slaren

ggml-cuda.cu

@@ -9568,6 +9568,10 @@ static ggml_backend_buffer_type_i ggml_backend_cuda_buffer_type_interface = {
 
 ggml_backend_buffer_type_t ggml_backend_cuda_buffer_type(int device) {
     // FIXME: this is not thread safe
+    if (device >= ggml_backend_cuda_get_device_count()) {
+        return nullptr;
+    }
+
     static struct ggml_backend_buffer_type ggml_backend_cuda_buffer_types[GGML_CUDA_MAX_DEVICES];
 
     static bool ggml_backend_cuda_buffer_type_initialized = false;
@@ -9793,7 +9797,6 @@ ggml_backend_buffer_type_t ggml_backend_cuda_split_buffer_type(const float * ten
     // FIXME: this is not thread safe
     static std::map<std::array<float, GGML_CUDA_MAX_DEVICES>, struct ggml_backend_buffer_type> buft_map;
 
-
     std::array<float, GGML_CUDA_MAX_DEVICES> tensor_split_arr = {};
 
     bool all_zero = tensor_split == nullptr || std::all_of(tensor_split, tensor_split + GGML_CUDA_MAX_DEVICES, [](float x) { return x == 0.0f; });

ggml-cuda.h

@@ -47,8 +47,6 @@ GGML_API int  ggml_backend_cuda_get_device_count(void);
 GGML_API void ggml_backend_cuda_get_device_description(int device, char * description, size_t description_size);
 GGML_API void ggml_backend_cuda_get_device_memory(int device, size_t * free, size_t * total);
 
-
-
 #ifdef  __cplusplus
 }
 #endif