Re: 6LoWPAN Stack

Jukka Rissanen

Hi Joakim,

On Fri, 2016-02-19 at 09:04 +0100, Joakim Eriksson wrote:
Hi Jukka!

On 19 Feb 2016, at 08:28, Jukka Rissanen <jukka.rissanen(a)linux.inte> wrote:

Hi Joakim,

On Thu, 2016-02-18 at 16:48 +0000, Joakim Eriksson wrote:

I just cloned the Zephyr repository and saw that the 6LoWPAN
was the same as the one I am used to - e,g, the Contiki 6LoWPAN
stack. How are you planning to develop it further? Are you going
sync it from Contiki or would you like Contiki developers to post
pull-requests to fixes also to Zephyr?
The plan is to sync it from Contiki when applicable. If you look
code, we needed to make lot of changes to uIP stack in order to
make it
work in Zephyr. The biggest change is that the IP stack is now re-
entrant e.g., there is no global buffer for network packets.
Because of
this it is not so simple to just pull changes from Contiki as
work needs to be done anyway.
Ok, yes - I expected that there would be quite som changes. But I
guess that they
will be the same changes at each sync! I will take a look at the
codebase and
see how much differences you have.

I guess if Zephyr is ported to more platforms (some of the ones we
have in Contiki)
maybe that would make developers do pull requests to both OS:es.

Quick question - what size of the compiled code did you get on the IP
stack when 
you moved from one buffer to re-entrant / multi buffers? 
I have not measured this. At the moment the IP stack is configured to
have separate TX and RX buffers. So in minimal configuration there
would be one TX and one RX buffer vs. in Contiki there would be only
one buffer that is used for both TX and RX.
User can also define at compile time how many network buffers he wants.

Anyway - congratulations - it looks like an exciting project and
will be happy contribute to it!

-- Joakim Eriksson, SICS
Thanks, and patches are welcome!
I will take a look and see if some of our work would be good to get
(we have LWM2M and other things fairly recently put into Contiki).
If have ported the lwm2m code to zephyr but it is not yet tested so I
have not sent it to review.


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