a driver selectable callback function. This is used in the Xen port to
allow controlling the domain's network setup from the domain building
environment at domain creation (vs. having to maintain/change this on a
dhcp server). The Xen network driver parses a command line passed in
from the domain builder.
kqueue provides a stateful and efficient event notification framework
currently supported events include socket, file, directory, fifo,
pipe, tty and device changes, and monitoring of processes and signals
kqueue is supported by all writable filesystems in NetBSD tree
(with exception of Coda) and all device drivers supporting poll(2)
based on work done by Jonathan Lemon for FreeBSD
initial NetBSD port done by Luke Mewburn and Jason Thorpe
