Newer Intel gigabit NICs include support for header splitting: they can
deliver the payload and headers for the same IP, TCP, or UDP packet to
separate addresses.

Long ago, FreeBSD implemented support for zero-copy receive using a
custom firmware version for the Alteon/Broadcom Tigon II that did
header splitting.  The original changes, and some discussion, are at:

http://people.freebsd.org/~ken/zero_copy/

Our stacks have diverged significantly since then, of course.  Does this
look like a reasonable starting point for implementing a general zero-copy
receive framework that could handle the Intel cards as well, or would it
be better to start from scratch?

-- 
  Thor Lancelot Simon	                                     tls@rek.tjls.com

  "We cannot usually in social life pursue a single value or a single moral
   aim, untroubled by the need to compromise with others."      - H.L.A. Hart