ping6 with ipv4 mapped ipv6 address

[Ritesh Agrawal <ritesh.agrawal%lithopstech.com@localhost>]

Hello,

I was trying to configure IPv4 mapped IPv6 address on NetBSD and tried 
local ping using ping6 for localhost and also directly connected system.

I have turned "v6only" sysctl off i.e. "net.inet6.ip6.v6only = 0". My 
interface configuration looks like:

vlan2: flags=c843<UP,BROADCAST,RUNNING,SIMPLEX,LINK2,MULTICAST> mtu 1500
capabilities=7ff80<TSO4,IP4CSUM_Rx,IP4CSUM_Tx,TCP4CSUM_Rx,TCP4CSUM_Tx,UDP4CSUM_Rx,UDP4CSUM_Tx,TCP6CSUM_Rx,TCP6CSUM_Tx,UDP6CSUM_Rx,UDP6CSUM_Tx,TSO6>
enabled=3ff00<IP4CSUM_Rx,IP4CSUM_Tx,TCP4CSUM_Rx,TCP4CSUM_Tx,UDP4CSUM_Rx,UDP4CSUM_Tx,TCP6CSUM_Rx,TCP6CSUM_Tx,UDP6CSUM_Rx,UDP6CSUM_Tx>
        vlan: 2 parent: agr0
        address: 00:30:48:bb:6b:28
        inet 192.168.15.156 netmask 0xffffff00 broadcast 192.168.15.255
        inet6 fe80::230:48ff:febb:6b28%vlan2 prefixlen 64 scopeid 0x6
        inet6 ::ffff:192.168.15.156 prefixlen 120

now if I try do to "ping6 ::ffff:192.168.15.156" it reports
"ping6: UDP connect: Invalid argument"
But if I do "telnet ::ffff:192.168.15.156 22" works fine for me.

I looked at in6_pcbind and it is failing for "if (in6p->in6p_lport || 
!IN6_IS_ADDR_UNSPECIFIED(&in6p->in6p_laddr))" check.

Do you think it is not allowed to do ping6 for IPv4 mapped IPv6 address?
I tried on Linux system and it works great on it. For localhost it 
responds locally and for locally connected system it sends out "ICMP6 
echo request" message. For TCP based connection IPv4 connection is 
established between host.

Thanks
Ritesh