Re: [lwip-users] lwIP for safety applications

[Pomeroy, Marty]

I am familiar with 61508 but never had to develop under it.  And while I
am a big fan of lwIP, I would be concerned about using it in a 61508
application - you might spend far more effort in certification than
porting it.

Let me push back a bit - Do you really need a full stack in a
"minimalistic bareboard"?  What traffic types are you going to use?  A
stack is useful when you have many traffic types.

I'm going to go on a bit because often in 61508 designs, the system is a
closed network.  If so, you can use one traffic type, and you can do it
with very little code, no stack required, everything handled at a layer
above.  For example, for a sensor board, configure IP and MAC addresses,
cobble up UDP packets, and send 'em over the ethernet port.  Done!  No
stack.

TCP/IP was designed to overcome unreliable connections.  In a closed
net, you can design adequate headroom, reliable connections, and use
simple packet types.  Sure you have to build fault tolerance at a layer
above, but you need that anyway.  For certification purposes, keep your
communication handling minimal and transparent.

Hope that helps!  And with humble apologies to the many capable and
bright lwIP developers and fans...

Marty