diff --git a/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/VtdReg.c b/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/VtdReg.c
index bc9f427a36..8dbc83fa2d 100644
--- a/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/VtdReg.c
+++ b/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/VtdReg.c
@@ -481,7 +481,7 @@ DumpVtdRegs (
       SourceId.Uint16 = (UINT16)FrcdReg.Bits.SID;
       DEBUG((DEBUG_INFO, "    Source - B%02x D%02x F%02x\n", SourceId.Bits.Bus, SourceId.Bits.Device, SourceId.Bits.Function));
       DEBUG((DEBUG_INFO, "    Type - %x (%a)\n", FrcdReg.Bits.T, FrcdReg.Bits.T ? "read" : "write"));
-      DEBUG((DEBUG_INFO, "    Reason - %x\n", FrcdReg.Bits.FR));
+      DEBUG((DEBUG_INFO, "    Reason - %x (Refer to VTd Spec, Appendix A)\n", FrcdReg.Bits.FR));
     }
   }