[lwip-users] RE: [lwip] architecture question

[Andy Knox]

Hi Peter

> I'd just like to kindly ask, if someone had a port to a similar platform
> working with 0.5. My target is 32 bit big endian, using interrupt-driven
> serial line (SLIP). I'm using the C68 compiler.

I am running lwIP on a PowerPC 850 platform, 32 bit, big endian.
We communicate over ethernet using the built in serial comms capabilities of
the processor. I am using the 'raw' API as we do not have a multi tasking
OS.
I now have ICMP, UDP and TCP running fine.

I wonder if your problem could be the same as one I had last week:
Moving from 0.4.1 to 0.5.0 I didn't get any ACKs from lwip when sending
small TCP segments. I guess that ICMP packets may have the same problem.

Here's Adam's off-list response to me which may help:

> Ah - I just found out the reason why you didn't get any ACKs when you
> switched to 0.5.0. Since you are using the raw API, I suspect that you
don't
> use the tcpip.c file at all. In the switch from the 0.4.x series to the
0.5.x
> series, TCP was slightly changed so that the timer handling wasn't done
> internally to TCP anymore. Now, the TCP timers has to be explicitly
called.
> Look in the file src/api/tcpip.c for an example how this is done.
>
> Since the fast TCP timer is responsible for handling and transmitting
delayed
> ACKs, problems like this will happen if it isn't called.
>
> The reason for moving the TCP timers out of the TCP module like this is to
> move as much operating system dependancies out of the protocol modules.

Cheers,
- Andy

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