5894 Want big theory statement on MAC's data path

Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Reviewed by: Rob Gulewich <robert.gulewich@joyent.com>
Reviewed by: Max Bruning <max@joyent.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

usr/src/uts/common/io/mac/mac.c

@@ -264,6 +264,13 @@
  * subflows before attempting a link property change.
  * Some of the above rules can be overridden by specifying additional command
  * line options while creating or modifying link or subflow properties.
+ *
+ * Datapath
+ * --------
+ *
+ * For information on the datapath, the world of soft rings, hardware rings, how
+ * it is structured, and the path of an mblk_t between a driver and a mac
+ * client, see mac_sched.c.
  */
 
 #include <sys/types.h>