SWDEV-406233 - Add notes on hipMemoryType and PointerGetAttributes API for unsupported cuda enum

Change-Id: I1175c12a55c7cd306a5aed3f1a400ae7525f4cb5

docs/user_guide/hip_porting_guide.md

@@ -461,11 +461,12 @@ In this case, memory type translation for hipPointerGetAttributes needs to be ha
 
 So in any HIP applications which use HIP APIs involving memory types, developers should use #ifdef in order to assign the correct enum values depending on Nvidia or AMD platform.
 
-As an example, please see the code from the link,
-github.com/ROCm-Developer-Tools/HIP/blob/develop/tests/catch/unit/memory/hipMemcpyParam2D.cc#L77-L96.
+As an example, please see the code from the [link](github.com/ROCm-Developer-Tools/HIP/blob/develop/tests/catch/unit/memory/hipMemcpyParam2D.cc).
 
 With the #ifdef condition, HIP APIs work as expected on both AMD and NVIDIA platforms.
 
+Note, cudaMemoryType enum value cudaMemoryTypeUnregstered is not supported currently in hipMemoryType, due to HIP functionality backward compatibility.
+
 ## threadfence_system
 Threadfence_system makes all device memory writes, all writes to mapped host memory, and all writes to peer memory visible to CPU and other GPU devices.
 Some implementations can provide this behavior by flushing the GPU L2 cache.

include/hip/hip_runtime_api.h

@@ -30,7 +30,6 @@ THE SOFTWARE.
 #ifndef HIP_INCLUDE_HIP_HIP_RUNTIME_API_H
 #define HIP_INCLUDE_HIP_HIP_RUNTIME_API_H
 
-
 #include <string.h>  // for getDeviceProp
 #include <hip/hip_version.h>
 #include <hip/hip_common.h>
@@ -164,6 +163,13 @@ typedef struct hipDeviceProp_t {
  /**
  * hipMemoryType (for pointer attributes)
  *
+ * @note hipMemoryType enum values are different from cudaMemoryType enum values.
+ * In this case, memory type translation for hipPointerGetAttributes needs to be handled properly
+ * on nvidia platform to get the correct memory type in CUDA. Developers should use #ifdef in order
+ * to assign the correct enum values depending on Nvidia or AMD platform.
+ *
+ * @note cudaMemoryTypeUnregistered is currently not supported due to HIP functionality backward
+ * compatibility.
  */
 typedef enum hipMemoryType {
     hipMemoryTypeHost = 0,    ///< Memory is physically located on host
@@ -2616,8 +2622,12 @@ hipError_t hipPointerSetAttribute(const void* value, hipPointer_attribute attrib
  *  @param [out]  attributes  attributes for the specified pointer
  *  @param [in]   ptr         pointer to get attributes for
  *
- *  Note: To get pointer's memory type, the parameter attributes has 'type' as member variable.
- *  The 'type' indicates input pointer is allocated on device or host.
+ *  @note: To get pointer's memory type, the parameter attributes has 'type' as member variable.
+ *  The 'type' indicates input pointer is allocated on device or host. That means the input pointer
+ *  must be returned or passed through an HIP API such as hipHostMalloc, hipMallocManaged,
+ *  hipHostRegister, etc. Otherwise, the pointer can't be handled by this API and attributes
+ *  returned hipErrorInvalidValue, due to the hipMemoryType enums values, unrecognized memory type
+ *  is currently not supported due to HIP functionality backward compatibility. 
  *
  *  @return #hipSuccess, #hipErrorInvalidDevice, #hipErrorInvalidValue
  *