Setting the right mtu when creating a domain

[Gustau Pérez]

   Hi,

   the box I'm doing testing with has all its interfaces set with mtu
9000. That is a problem at domain creation time, because taps are set to
1500, and bridge [1] is created with the mtu of the first interface added.

   So if you're using an mtu different than 1500 (it could also be less
than 1500 for any special reason) in an interface part of the bridge
(and thus the bridge will have mtu != 1500) that would cause problems
with the tap of the new domain.

   I did a simple patch to tools/hotplug/FreeBSD/vif-bridge to get the
bridge mtu and create the tap with the right mtu [2]. I'm not sure if
this can be accomplished somewhere else, but I thought this way the
bridge can be configured in rc.conf and our vif-bridge may be able to
fetch the right mtu. Nothing from ports is used (sed from base system).

   Best,

   G.

   [1] man 4 bridge
   [2] http://dpaste.com/2HN8SHN