From mboxrd@z Thu Jan  1 00:00:00 1970
From: bob@lintilla.demon.co.uk (Bob Cousins)
To: ecos-discuss@sourceware.cygnus.com
Subject: Re: [ECOS] TCP/IP Stack for eCos
Date: Fri, 23 Apr 1999 16:08:00 -0000
Message-id: <3720f34a.45111647@post.demon.co.uk>
References: <3720ABE2.7672F6C0@microplex.com> <3720c0d0.32189806@post.demon.co.uk> <3720D7A4.2E60AF91@microplex.com> <3720D7A4.2E60AF91@microplex.com>
X-SW-Source: 1999-04/msg00010.html

Hi Fred Fierling,

>Is Xinu a zero copy stack (i.e. only passes pointers)?  This is important
>because an RTOS often runs on wimpy hardware.

Ah, now we're talking requirements. Data buffering is a topic by itself ;-) Xinu
isn't zero copy, but it is fairly easy to change. I designed a stack based
around a flexible buffer structure similar to the Unix mbuf. Adding this type of
thing to Xinu/TCP would be more work, changing all the references etc,
rethinking the fragmentation/reassembly. 

The way I see it is that Xinu/TCP is a fairly close fit which more or less works
and provides a fairly clean base architecture to work on, and would provide a
quick way to get something working. (In comparison to other stacks I know of
such as FreeBSD, Linux, KA9Q, WATTCP et al). This could then be developed to
revise the architecture and implement better performance etc.

I'm afraid I'm on sketchy ground here as I'm not familiar with eCos or its
current targets. My typical requirement is for a networked data acquisition
unit, ideally running SNMP, but at least capable of UDP over ethernet. A PC386
card is probably too expensive but the software would be easy for me to put
together. Something smaller should do, the data acquisition is trivial, it could
be done with a PIC and UDP at a stretch, but SNMP out of the question, so I'm
thinking 8051 variant. Xinu is attractive because it is simple and has SNMP code
too. Unfortunately I've little time or money to persue either vigorously at the
moment, so this is a background activity.
-- 
Bob Cousins, Software Engineer.
http://www.lintilla.demon.co.uk/
"We demand that we may, or may not, be philosophers!"