routing in VIMAGE jails with different versions

[J David]

Hello,

If a 9-STABLE amd64 host compiled with VIMAGE support contains a jail
running i386 code with a vnet interface, how does one set the default route
inside the jail?

Ifconfig and the network work fine, but route returns:

# route add default 192.168.0.1
route: writing to routing socket: Invalid argument
add net default: gateway 192.168.0.1: Invalid argument

The behavior appears the same whether the jail is running 8.3-i386 or
9.1-i386.

Based on this:

http://lists.freebsd.org/pipermail/freebsd-amd64/2011-October/014050.html

It looks like this there was a host-side patch for this in the 8.2
timeframe, but I compared the patch to the 9-STABLE source for
sys/net/rtsock.c and it's not there.  As that's from two years ago, there's
probably a reason it didn't make it in, so does anyone know what is the
right way to manage routes in VIMAGE jails?

Thanks for any advice!