1 files changed, 15 insertions, 11 deletions
diff --git a/MdePkg/Include/Protocol/SmmSwDispatch2.h b/MdePkg/Include/Protocol/SmmSwDispatch2.h
index c64e2b226f..a4c41663c8 100644
--- a/MdePkg/Include/Protocol/SmmSwDispatch2.h
+++ b/MdePkg/Include/Protocol/SmmSwDispatch2.h
@@ -65,16 +65,20 @@ typedef struct _EFI_SMM_SW_DISPATCH2_PROTOCOL  EFI_SMM_SW_DISPATCH2_PROTOCOL;
   DispatchHandle contains a unique handle which may be used later to unregister the function 
   using UnRegister().
 
-  @param[in]  This               Pointer to the EFI_SMM_SW_DISPATCH2_PROTOCOL instance.
-  @param[in]  DispatchFunction   Function to register for handler when the specified software 
-                                 SMI is generated. 
-  @param[in]  RegisterContext    Pointer to the dispatch function's context.
-                                 The caller fills this context in before calling
-                                 the register function to indicate to the register
-                                 function which Software SMI input value the
-                                 dispatch function should be invoked for.
-  @param[out] DispatchHandle     Handle generated by the dispatcher to track the
-                                 function instance.
+  Note that the modifiers for the parameter RegisterContext are IN, OUT, while they are IN, CONST
+  in the PI 1.2 errta B spec. This in-consistency is for support for the case where SwSmiInputValue
+  is set to -1, a unique value will be returned in the RegisterContext structure.
+
+  @param[in]  This                 Pointer to the EFI_SMM_SW_DISPATCH2_PROTOCOL instance.
+  @param[in]  DispatchFunction     Function to register for handler when the specified software 
+                                   SMI is generated. 
+  @param[in, out] RegisterContext  Pointer to the dispatch function's context.
+                                   The caller fills this context in before calling
+                                   the register function to indicate to the register
+                                   function which Software SMI input value the
+                                   dispatch function should be invoked for.
+  @param[out] DispatchHandle       Handle generated by the dispatcher to track the
+                                   function instance.
 
   @retval EFI_SUCCESS            The dispatch function has been successfully
                                  registered and the SMI source has been enabled.
@@ -91,7 +95,7 @@ EFI_STATUS
 (EFIAPI *EFI_SMM_SW_REGISTER2)(
   IN  CONST EFI_SMM_SW_DISPATCH2_PROTOCOL  *This,
   IN        EFI_SMM_HANDLER_ENTRY_POINT2   DispatchFunction,
-  IN  CONST EFI_SMM_SW_REGISTER_CONTEXT    *RegisterContext,
+  IN  OUT   EFI_SMM_SW_REGISTER_CONTEXT    *RegisterContext,
   OUT       EFI_HANDLE                     *DispatchHandle
   );