[lwip-users] Re: [lwip] Has anyone looked at porting lwIP to Redhat's ECOS?

[Adam Dunkels]

On Tuesday 09 October 2001 15:07, you wrote:
> Hmm...for some reason I still seem to get 2 copies of
> your [Adam] messages - my email address is on the 'to'
> list as well as address@hidden  Yet its OK from other
> poster's on the mailing list.  Not a big deal anyway.

That was just because I used the "reply to all" function in my mailprogram. 
Since the reply-to header now works as it should, using the "reply" function 
suffices.

> > 512k is quite a lot for running lwIP with a small
> > web server. The one running
> > at http://lwip-demo.sics.se/ has 100k flask and 10k
> > RAM and works like a
> > charm!
>
> I was thinking of using Boa (http://www.boa.org/).
> However, it uses select() which I'd need to add.  I
> guess it wouldn't be too hard to copy the BSD
> implementation.

I haven't really looked at Boa, but I would recommend using a specialized 
lwIP web server instead of running one on top of a socket emulation library. 
The reason for this is that lwIP supports no-copy sending in a way that 
sockets doesn't - it is possible to send data directly from ROM/Flash instead 
of buffering it in RAM first.

This is the way the lwip-demo.sics.se web server works. Everything except the 
statistics and the stack usage numbers is static, and therefore is stored in 
Flash memory. The Ethernet device driver reads directly from that memory when 
sending the packets and thereby avoids wasting a lot of RAM.

I guess that much of the code from Boa could be used (gunzipping, directory 
generation, etc.) but the low-level socket stuff should be replaced with lwIP 
equivalents. And the places where data copying can be avoided should be 
defined and the NETCONN_NOCOPY option should be used. That can save large 
amounts of memory.

> > I'll se if I can get hold of the book, and perhaps a
> > simple PPP might be
> > found in future versions of lwIP.
>
> I got James Carlson's minimal PPP code running in
> about 10 minutes under Cygwin.  Again, I guess this
> wouldn't be too hard to plug this in in place of the
> VTUN driver.

Great! It would be nice to be able to integrate at least experimental PPP 
support in version 0.4.2.

/adam
-- 
Adam Dunkels <address@hidden>
http://www.sics.se/~adam
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