I have the UART setup for debugging output.  The kicker with this is that 
introducing enough delay by enabling enough debugging, or even if I define the 
debug output as a delay, makes some of the problems disappear.  I've also 
enabled stats and have studied that.  

The driver, yeah, my guess is that's where the problem is.  It's the driver 
provided by Luminary, so I assumed it was well tested, but I'm questioning this 
since the actual lwIP code should be stable enough for what I'm doing.  

I have been studying ethernet and TCP/IP for awhile now, so I have the basics 
down but am not too fluent in the fine details.  Not using an RTOS.  I believe 
the driver is using lwIP pbufs, and setting pointers to them....lately I'm 
realizing I'll have to learn how the code works better to debug effectively.  
However, it is nice to know I'm not the only one who has spent great amounts of 
time on this!

--- On Sun, 8/16/09, Chris Strahm <[email protected]> wrote:

From: Chris Strahm <[email protected]>
Subject: Re: [lwip-users] Duplicate sequence numbers
To: "Mailing list for lwIP users" <[email protected]>
Date: Sunday, August 16, 2009, 11:24 PM



 
 

The descriptions you have given leave too many 
possibilities.  Ethernet is very complex.  There are a zillion 
potential issues between the driver, the lwIP configuration, options, and 
potential RTOS.  Not much anyone can do for you without a lot more details 
on what your setup is and some debugging data.
 
For example,  do you have a console/uart setup to output 
DEBUG strings?  You really need that.  Without that you are 
blind.  lwIP has a lot of stats and debug info that will help you figure 
out what is going on inside lwIP.  You will need to get fully aquainted 
with the debug facilities of lwIP.
 
You mentioned before setting your pbuf size to 256 
bytes.  What is the size of your driver/DMA/MAC buffers?  They should 
probably be set the same to 256 bytes.  Depending on how the driver is 
writtem, it may or may not support mixed sizes and full fragmentation.  
Just the driver alone is a really big Black Box full of potential 
headaches.
 
Troubleshooting skills here are a really big plus.  
Getting lwIP up and running is not trivial.  You have to start at the 
bottom and build your way up from there.  I found it hard to get very 
far on this kind of code until I developed enough understanding of what makes 
Ethernet tic from top to bottom.  There is a learning curve.  You may 
be on this longer than you expected.  I sure have been.
 
Hope this helps.
 
Chris.
 
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