>>	there are a couple of issues remain, however (i should have appended
>>	it to the PR):
>>	- for off-link destinations, the primary (1st)  address will be used as
>>	  the source address on packets.  we can still trick it by changing
>>	  rt->rt_ifa though.
>>	- if the primary (1st) address gets removed, subnet route (like 10/8
>>	  for 10.0.0.1/8) goes away.  to fix this we need to change rt_ifinit()
>>	  substantially.
>
>for this to work really well, i feel that there should be a way to
>*insert* an address at the head of the list of addresses for a given
>interface.
>
>i've had "problems" where the "primary" ipv4 address was removed via
>"-alias" and then a new address was added via "alias".
>
>"alias" adds to the end of list, "-alias" removes arbitrarily from the
>list, "delete" removes the head of the list, and the absence of the
>alias keyword *sets* the head of the list (at the same time deleting
>what was there).  the "insert at the head of the list" bit is missing.

	you can use the following:
	# ifconfig wi0 <secondary address> -alias

	for IPv6, we forbid the following form as IPv4 behavior assumed that
	the primary (1st one) gets removed, and it is a bad assumption to make.
	# ifconfig wi0 -alias

itojun