- * fields, plus any padding to round this up to the
- * nearest multiple of the block size (16 bytes).
- * Padding will be added by the implementation.
+ * fields, plus any padding to round this up to the
+ * nearest multiple of the block size (16 bytes).
+ * Padding will be added by the implementation.
+ *
+ * - Note that PMDs may modify the memory reserved
+ * (first 18 bytes and the final padding).