Re: [lwip-users] lwipopts: TX_SINGLE_PBUF

[Dirk Ziegelmeier]

Simon tried to explain you this:

https://git.savannah.gnu.org/cgit/lwip.git/tree/src/include/lwip/opt.h#n1593

Dirk

On Fri, Oct 20, 2017 at 2:57 PM, David Gauchard <address@hidden> wrote:

On ven., oct. 20, 2017 at 09:32:14 -0300, Sergio R. Caprile wrote:
> I can comment on the ESP8266 side.
> It does not use 1.4.1 nor 2.0.3 but a custom (heavily modified) git head
> grabbed some time between 1.4.1 and 2.0 when there was a probable 1.5 to
> come, as that is what they advertise on their VERSION strings.
> They have their own sort-of-OS taking care of all the WiFi stuff and
> providing some non-WiFi-used CPU time to the rest of the "tasks", which must
> use their custom C library functions.
>
> But I guess you know quite better than me on this very subject, so my former
> comment is probably useless for you and just for the rest of the readers.

As explained,  the lwip stack that is actually and currently running on my
esp8266 is the latest clear stable unpatched lwip2 sources.  The patched
lwip1.4 from espressif is completely removed (check the link from my
previous mail).  It is running quite well and solves number of problems
linked to the tcp stack on esp8266/arduino.

> AFAIK, pbufs are single (non-chained) on the Tx side and probably multiple
> (chained) on the Rx side, depending on the memory allocation strategy, which
> serves the purpose of avoiding memory fragmentation issues. Maybe there's
> something I'm missing, but I think probably your needs are more on the alloc
> world and not TCP/IP functions related ?

pbufs are generally single pbufs, because I configured lwipopts.h as so (it
is not working without this specific conf).  Still I have sometimes a
sanity check which is raised:

https://github.com/d-a-v/esp82xx-nonos-linklayer/blob/12b7c2f0d46e0d4efdc5494f94bdd7268b627cc7/glue-lwip/lwip-git.c#L183


> Off-topic: I gave up with that chip, I'm currently fighting the ESP32.
> Though it still uses this custom lwIP fork, it has JTAG...

esp8266/esp8285 are still great and running quite well with a proper ip
stack :)

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