Describe PMBR in terms of syslinux GPT extension.

show.c

Index: show.c
diff --git a/show.c b/show.c
index 5b34819ee4cca2ca85b9855456623b80ffa78774..eb0f617906ee8978526ee7aa068eb74cde13887c 100644
--- a/show.c
+++ b/show.c
@@ -183,7 +183,18 @@ show(int fd __unused)
                         }
 			break;
 		case MAP_TYPE_PMBR:
-			printf("PMBR");
+			mbr = m->map_data;
+                        if (le16toh(mbr->magic_number) == MBR_MAGIC)
+                        {
+                                char *s;
+                                uuid_to_string(&mbr->boot_guid, &s, NULL);
+                                printf("PMBR (Boot GUID: %s)", s);
+                                free(s);
+                        }
+                        else
+                        {
+                            printf("PMBR (no magic)");
+                        }
 			break;
 		}
 		putchar('\n');