Comment 1 for bug 822601

Seems there are two aliied configuration options MACVLAN and MACVTAP. Both are currently experimental.

    config MACVLAN
        tristate "MAC-VLAN support (EXPERIMENTAL)"
        depends on EXPERIMENTAL
        ---help---
          This allows one to create virtual interfaces that map packets to
          or from specific MAC addresses to a particular interface.

          Macvlan devices can be added using the "ip" command from the
          iproute2 package starting with the iproute2-2.6.23 release:

          "ip link add link <real dev> [ address MAC ] [ NAME ] type macvlan"

          To compile this driver as a module, choose M here: the module
          will be called macvlan.

    config MACVTAP
        tristate "MAC-VLAN based tap driver (EXPERIMENTAL)"
        depends on MACVLAN
        help
          This adds a specialized tap character device driver that is based
          on the MAC-VLAN network interface, called macvtap. A macvtap device
          can be added in the same way as a macvlan device, using 'type
          macvlan', and then be accessed through the tap user space interface.

          To compile this driver as a module, choose M here: the module
          will be called macvtap.

So far we do have MACVLAN turned on:

    debian.master/config/config.common.ubuntu:CONFIG_MACVLAN=m
    debian.master/config/config.common.ubuntu:# CONFIG_MACVTAP is not set

As they seem to be opt-in devices and seem to be self contained it seems safe to enable this. Will spin a patch and send it to kernel-team@ for review.