onnxruntime/docs/AddingExecutionProvider.md

# Adding a new execution provider

* Create a folder under onnxruntime/core/providers
* Create a folder under include/onnxruntime/core/providers, it should has the same name as the first step.
* Create a new class, which must inherit from [IExecutionProvider](../include/onnxruntime/core/framework/execution_provider.h). The source code should be put in 'onnxruntime/core/providers/[your_provider_name]'
* Create a new header file under include/onnxruntime/core/providers/[your_provider_name]. The file should provide one function for creating an OrtProviderFactoryInterface. You may use 'include/onnxruntime/core/providers/cpu/cpu_provider_factory.h' as a template. You don't need to provide a function for creating MemoryInfo.
* Put a symbols.txt under 'onnxruntime/core/providers/[your_provider_name]'. The file should contain all the function names that would be exported from you provider. Usually, just a single function for creating provider factory is enough.
* Add your provider in onnxruntime_providers.cmake. Build it as a static lib.
* Add one line in cmake/onnxruntime.cmake, to the 'target_link_libraries' function call. Put your provider there.


Examples:     

 * [CPU Execution
       Provider](../onnxruntime/core/providers/cpu/cpu_execution_provider.h)               
 * [CUDA Execution
       Provider](../onnxruntime/core/providers/cuda/cuda_execution_provider.h)               
 * [MKL-DNN Execution
       Provider](../onnxruntime/core/providers/mkldnn/mkldnn_execution_provider.h)               


# Using the execution provider
1. Create a factory for that provider, by using the c function you exported in 'symbols.txt'
2. Put the provider factory into session options
3. Create session from that session option
e.g.

```c
  OrtEnv* env;
  OrtInitialize(ORT_LOGGING_LEVEL_WARNING, "test", &env)
  OrtSessionOptions* session_option = OrtCreateSessionOptions();
  OrtProviderFactoryInterface** factory;
  OrtCreateCUDAExecutionProviderFactory(0, &factory);
  OrtSessionOptionsAppendExecutionProvider(session_option, factory);
  OrtReleaseObject(factory);
  OrtCreateSession(env, model_path, session_option, &session);
```