MdePkg: Increment EFI_DEBUG_IMAGE_INFO_TYPE_NORMAL

The intention here is to enable old tools encountering the new standard
format to understand that they don't understand the layout.

This will break old tools in situations where they could have worked,
i.e. where what is loaded is in fact a PE, but it seems preferable to
allow new tools, which are aware of the new structure fields, to
reliably detect and access these whenever they are present.

MdePkg/Include/Guid/DebugImageInfoTable.h

@@ -25,7 +25,8 @@
 #define EFI_DEBUG_IMAGE_INFO_UPDATE_IN_PROGRESS  0x01
 #define EFI_DEBUG_IMAGE_INFO_TABLE_MODIFIED      0x02
 
-#define EFI_DEBUG_IMAGE_INFO_TYPE_NORMAL  0x01
+#define EFI_DEBUG_IMAGE_INFO_TYPE_LEGACY_PE   0x01
+#define EFI_DEBUG_IMAGE_INFO_TYPE_NORMAL      0x02
 
 typedef struct {
   UINT64                  Signature;          ///< A constant UINT64 that has the value EFI_SYSTEM_TABLE_SIGNATURE
@@ -35,8 +36,14 @@ typedef struct {
 
 typedef struct {
   ///
-  /// Indicates the type of image info structure. For PE32 EFI images,
-  /// this is set to EFI_DEBUG_IMAGE_INFO_TYPE_NORMAL.
+  /// Indicates the available image info in this structure.
+  /// EFI_DEBUG_IMAGE_INFO_TYPE_NORMAL (i.e. 2) indicates that PdbPath and
+  //  DebugBase fields are present (the loaded image may or may not be a PE).
+  /// Note that EFI_DEBUG_IMAGE_INFO_TYPE_LEGACY_PE (i.e. 1) was used in
+  /// earlier versions to indicate that the loaded image is a PE, using a
+  /// previous version of this structure which did not include the PdbPath
+  /// and DebugBase fields (therefore knowledge of the specific image type
+  /// was required in order to access debug symbolication information).
   ///
   UINT32                       ImageInfoType;
   ///
@@ -47,7 +54,13 @@ typedef struct {
   /// Indicates the image handle of the associated image.
   ///
   EFI_HANDLE                   ImageHandle;
-  CHAR8                      *PdbPath;
+  ///
+  /// Symbol file path for debug symbolication.
+  ///
+  CHAR8                        *PdbPath;
+  ///
+  /// Image base address for debug symbolication.
+  ///
   UINTN                        DebugBase;
 } EFI_DEBUG_IMAGE_INFO_NORMAL;