port-xen/41878: cannot create static ARP entries on a domU

[manu%spci.fr@localhost]

>Number:         41878
>Category:       port-xen
>Synopsis:       cannot create static ARP entries on a domU
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-xen-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Aug 12 16:50:00 +0000 2009
>Originator:     Emmanuel Dreyfus
>Release:        NetBSD 5.0_STABLE
>Organization:
>Environment:
x
System: NetBSD glop.example.net 5.0_STABLE NetBSD 5.0_STABLE (XEN3_DOMU) #0: 
Sat Aug 1 15:33:02 UTC 2009 
builds%b7.netbsd.org@localhost:/home/builds/ab/netbsd-5/i386/200908010000Z-obj/home/builds/ab/netbsd-5/src/sys/arch/i386/compile/XEN3_DOMU
 i386
Architecture: i386
Machine: i386

>Description:
On NetBSD-5.0, adding a static ARP entry with arp -s will fail with a
kernel message:
# arp -s 192.0.2.15 00:16:3e:52:c1:ec
arp_rtrequest: bad gateway value

Despite the error message, a static entry is created in the routing table:
# netstat -nr|grep 15
192.0.2.15       00:16:3e:52:c1:ec  UHS        0        1      -  xennet

However, nothing appears in the ARP table:
# arp -a|grep 15 || echo nothing!
nothing!

And any attempt to exchange data with the host fails with the kernel
message:
arplookup: unable to enter address for 
    192.0.2.15@ff:01:d1:ca:c1:36:52:06:c0:00:02:0f:08:00:61:63 
    on null (could not allocate llinfo)
arpresolve: can't allocate llinfo on xennet0 for 192.0.2.15

>How-To-Repeat:
On a NetBSD 5.0 domU:
ip=192.0.2.15
mac=00:16:3e:52:c1:ec
arp -d $ip
arp -s $ip $mac
ping $ip

>Fix:
Unknown yet. That problem did not exist with the same setup (dom0, Xen
version) when the domU was running NetBSD-4.0