IPv6 source address selection and privacy extensions

["Bruno Prémont" <bonbons@linux-vserver.org>]

>From Documentation/networking/ip-sysctl.txt:

use_tempaddr - INTEGER
        Preference for Privacy Extensions (RFC3041).
          <= 0 : disable Privacy Extensions
          == 1 : enable Privacy Extensions, but prefer public
                 addresses over temporary addresses.
          >  1 : enable Privacy Extensions and prefer temporary
                 addresses over public addresses.
        Default:  0 (for most devices)
                 -1 (for point-to-point devices and loopback devices)

Is it possible with current kernel to have >1 make temporary addresses
used by default but have manual or dynamic (e.g. MAC based) address used
for some destination addresses/subnets?
If it's possible, how can this be done (adding a hint to ip-sysctl.txt
would then make it easy for others to find)

With IPv4 this can be done via `ip route add $subnet/$prefix src $addr`
though the same does not work for IPv6.

Thanks,
Bruno