Re: [lwip-users] Problem accessing "httpd" web server from a Linux PC

[Sergio R. Caprile]

Hello Roland,
well, obviously lwIP does not know about Windoze or Linux on the other
end of the wire, and even though the http server could be picky about
that because the browser sends that info, it does not. There is
something that happens when you connect to the Linux box that triggers a
problem probably in your Eth driver.
Looking at your capture files I see two things catching my eye. Frame
#11 is red, because of a TCP checksum error, and its length is way over
the standard Ethernet frame length (1900+ bytes). Both can point to a
broken Ethernet driver, or a broken port. (if you did not enable
checksum check on your wireshark, you should).
The TCP checksum can be offloaded to the Eth chip or calculated by lwIP,
you should check those options in your lwipopts.h and/or lwip/opt.h and
be aware of that, and both lwIP and your Eth driver must agree on who
does what.

The httpd server runs in the same thread as lwIP, it should work
flawlessly even in NO_SYS=0 as long as you don't call RAW API functions
from other threads (including interrupts).
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