HEADS UP: Kernel ABI for network device drivers changes

Over the last two days, I've modified the size of 'struct ifnet' in order
to add several spare fields.  The goal is to break the ABI now just before
5.3 so that we can preserve network interface driver ABI more easily over
the lifetime of 5.x even as we continue the network stack work.  The
result of this change is that all network interface drivers on the 6.x,
5.x, and 5.3 branches must be recompiled when you update to the latest
kernel.  Since few third party network drivers exist right now, we figured
it was better to do it now than after the release as final compiled third
party drivers start to turn up.  In addition to adding the fields, we also
moved if_handoff() from being an inline to a function, as we anticipate
changing the way that network device dispatch occurs.

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert_at_fledge.watson.org      Principal Research Scientist, McAfee Research