Add some description for behaviour of the urMemGetNativeHandle for CUDA and HIP

Author: Hugh Delaney

scripts/core/CUDA.rst

@@ -148,6 +148,25 @@ take the extra global offset argument. Use of the global offset is not
 recommended for non SYCL compiler toolchains. This parameter can be ignored if
 the user does not wish to use the global offset.
 
+Interoperability
+================
+
+Unified Runtime offers a number of entry points in order to get native handles
+for UR objects. The native handle may refer to a number of different native CUDA
+types, depending on the entry point called.
+
+- ${x}MemGetNativeHandle stores a ``CUdeviceptr`` in the ${x}_native_handle_t
+  argument passed. The ``CUdeviceptr`` will be resident on the
+  ${x}_device_handle_t provided as an argument, if the device shares a context
+  with the ${x}_mem_handle_t. If the ${x}_device_handle_t argument passed to
+  ${x}MemGetNativeHandle is ``nullptr``,
+  ``UR_RESULT_ERROR_UNSUPPORTED_FEATURE`` will be returned.
+
+..
+  TODO: add more descriptions of the native types that will be stored in
+  ur_native_handle_t types for different calls to urTypeGetNative and
+  urTypeCreateWithNativeHandle.
+
 Other Notes
 ===========
 

scripts/core/HIP.rst

@@ -91,6 +91,25 @@ take the extra global offset argument. Use of the global offset is not
 recommended for non SYCL compiler toolchains. This parameter can be ignored if
 the user does not wish to use the global offset.
 
+Interoperability
+================
+
+Unified Runtime offers a number of entry points in order to get native handles
+for UR objects. The native handle may refer to a number of different native HIP
+types, depending on the entry point called.
+
+- ${x}MemGetNativeHandle stores a ``hipDeviceptr_t`` in the
+  ${x}_native_handle_t argument passed. The ``hipDeviceptr_t`` will be resident
+  on the ${x}_device_handle_t provided as an argument, if the device shares a
+  context with the ${x}_mem_handle_t. If the ${x}_device_handle_t argument
+  passed to ${x}MemGetNativeHandle is ``nullptr``,
+  ``UR_RESULT_ERROR_UNSUPPORTED_FEATURE`` will be returned.
+..
+  TODO: add more descriptions of the native types that will be stored in
+  ur_native_handle_t types for different calls to urTypeGetNative and
+  urTypeCreateWithNativeHandle.
+
+
 Other Notes
 ===========
 

scripts/core/memory.yml

@@ -435,7 +435,7 @@ params:
     - type: $x_device_handle_t
       name: hDevice
       desc: |
-            [in] handle of the device that the native handle will be resident on.
+            [in] handle of the device on which the native handle will reside.
     - type: $x_native_handle_t*
       name: phNativeMem
       desc: |