> "replace x with y" 

There's an idea.  Anyways, here is a brief
overview of what you need to know:

1) you transmit and receive mbufs, not npkts

2) the transmit routine, really weirdly, is
   called fubar_start().
 
3) initialization is different.  Your dll
   fubar_entry() calls up into the stack with
   dev_attach() which in turn calls back down
   to the driver fubar_attach() function once
   for each hardware instance.  fubar_init()
   may be called over and over again.  This is
   very different from io-net.  You MUST ensure
   that fubar_init() is safe to call over and
   over again.

4) io-pkt drivers don't create threads - you
   want to always run as a "stack thread".  Use
   the stack timer callouts for periodic wakeup.
 
5) ensure that your driver registers for shutdown
   to avoid systems hangs after io-pkt faults - 
   you must quiesce the hardware to avoid memory
   corruption.

--
aboyd

> create an io-pkt driver 

It is worth mentioning that the BIG difference
between running an io-net driver with the shim
and a native io-pkt driver, is that you get rid
of the thread switch on packet receive.

Experimentation has shown that on a fast cpu on 
100mbit ethernet, you will see the same throughput 
with both, and also very low cpu utilitization 
with both.

Only if you are pushing gige, or are running on a 
slow cpu, does this thread switch become noticeable.

Ok, there's also the conversion between npkts and
mbufs, but that's pretty hard to notice from either
a throughput or cpu utilitization standpoint.

--
aboyd