svn commit: r253617 - head/sys/kern

Marcel Moolenaar marcel at
Wed Jul 24 18:13:43 UTC 2013

Author: marcel
Date: Wed Jul 24 18:13:43 2013
New Revision: 253617

  Further restrict the MAC addresses that we use for UUID generation
  to those that are universally administered. While it is possible to
  add locally administered MAC addresses, it's unclear whether those
  are (expected) to be more unique than random multicast MAC addresses
  or not.
  With many U-Boot configurations assigning fixed and non-official MAC
  addresses to ethernet ports and without setting the 'X' flag, this
  change may have very little value in the embedded (development)
  space. Uniqueness of the universally administered addresses is non-
  existent on the (H/W) bench and questionable under the (S/W) desk.
  In short: this change is aimed at production environments...


Modified: head/sys/kern/kern_uuid.c
--- head/sys/kern/kern_uuid.c	Wed Jul 24 17:55:08 2013	(r253616)
+++ head/sys/kern/kern_uuid.c	Wed Jul 24 18:13:43 2013	(r253617)
@@ -203,10 +203,10 @@ uuid_ether_add(const uint8_t *addr)
 	int i, sum;
-	 * Validate input. No multicast addresses and no addresses that
-	 * are all zeroes.
+	 * Validate input. No multicast (flag 0x1), no locally administered
+	 * (flag 0x2) and no 'all-zeroes' addresses.
-	if (addr[0] & 0x01)
+	if (addr[0] & 0x03)
 		return (EINVAL);
 	sum = 0;
 	for (i = 0; i < UUID_NODE_LEN; i++)

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