diff --git a/UefiCpuPkg/ResetVector/Vtf0/Ia16/Real16ToFlat32.asm b/UefiCpuPkg/ResetVector/Vtf0/Ia16/Real16ToFlat32.asm
index 146df600a6..bc68c8dd74 100644
--- a/UefiCpuPkg/ResetVector/Vtf0/Ia16/Real16ToFlat32.asm
+++ b/UefiCpuPkg/ResetVector/Vtf0/Ia16/Real16ToFlat32.asm
@@ -21,6 +21,12 @@ BITS    16
 ;
 ; Modified:  EAX, EBX
 ;
+; @param[out]     DS       Selector allowing flat access to all addresses
+; @param[out]     ES       Selector allowing flat access to all addresses
+; @param[out]     FS       Selector allowing flat access to all addresses
+; @param[out]     GS       Selector allowing flat access to all addresses
+; @param[out]     SS       Selector allowing flat access to all addresses
+;
 TransitionFromReal16To32BitFlat:
 
     debugShowPostCode POSTCODE_16BIT_MODE
diff --git a/UefiCpuPkg/ResetVector/Vtf0/Main.asm b/UefiCpuPkg/ResetVector/Vtf0/Main.asm
index ebfb9015d4..57f080688b 100644
--- a/UefiCpuPkg/ResetVector/Vtf0/Main.asm
+++ b/UefiCpuPkg/ResetVector/Vtf0/Main.asm
@@ -24,6 +24,11 @@ BITS    16
 ; @param[in,out]  DI       'BP': boot-strap processor, or
 ;                          'AP': application processor
 ; @param[out]     RBP/EBP  Address of Boot Firmware Volume (BFV)
+; @param[out]     DS       Selector allowing flat access to all addresses
+; @param[out]     ES       Selector allowing flat access to all addresses
+; @param[out]     FS       Selector allowing flat access to all addresses
+; @param[out]     GS       Selector allowing flat access to all addresses
+; @param[out]     SS       Selector allowing flat access to all addresses
 ;
 ; @return         None  This routine jumps to SEC and does not return
 ;