>>>>> "David" == David Kelly <dkelly@hiwaay.net> writes:

David> John Nemeth writes:
>> On Jun 23,  3:09pm, David Kelly wrote:
>> } How much does it hurt for pppd(8) or ppp(8) to be outside the kernel?
>> 
>> ppp(4) is inside the kernel.  pppd(8)'s job is to dial the modem,
>> login,  and setup the connection.  Once the connection is established,
>> ppp(4) in the kernel takes over and handles the actual data transfer.

David> FreeBSD's man says:

Hmm, I had a look in the NetBSD kernel source and as far as I can see
both SLIP and PPP are there.  FreeBSD apparantly does it in another
way.  I guess I should have a look at the FreeBSD PPP code as well. 

The speed issue is, as has been pointed out not a real problem for
AX25 since it is used over lines that slow and are not utilized very
well.  A Sun 3 should have little problem keeping up with it unless it
starts to swap (like my diskless 3/50 when I started Emacs on it). 
I ran AX25 on a 8 MHZ 68000 and although I kept copying down to once
when traversing it to do byte stuffing (adding escape characters where
needed), the impact on the overall system performance could not be
noticed.

Accessing the serial port can be done via the serial I/O device, no
need to bang any hardware.

There are other problems to look into, like how to deal with ARP, how
to make a good API for AX25 (sockets somehow?), timers and possibly
threading.

The good points of having AX25 outside the kernel (in my opinion) is
that it makes it easier to port to other UNIX flavours and one does
not have to mess getting the code into the NetBSD code base.  
The advantage of having it in the kernel would be to have a tighter
integration with other protocols and performance (which is not really
a big issue as outlined above).