Re: lwip 1.3.2 port

[Simon Kallweit <simon.kallweit@intefo.ch>]

John Dallaway wrote:
> Hi Simon
> 
> Simon Kallweit wrote:
> 
>>>>> c) There are a lot of small changes under src/netif/ppp/ including
>>>>> function renaming. I understand that you have your own PPP requirements
>>>>> to consider but I think we should stick closer to the master sources
>>>>> for the CVS check-in. Unless your changes have already been accepted
>>>>> upstream?
>>>>>       
>>>> Well, yesterday night I have checked the lwip HEAD, and it looks like
>>>> there has been lots of work done in the ppp departement. It now supports
>>>> polling and multi-threaded support out of the box. So it might be
>>>> considerable to directly use the current HEAD for inclusion into eCos
>>>> and keep it updated with the lwip repository until we hit the next
>>>> stable release. Backporting the ppp changes to the 1.3.2 codebase is a
>>>> bit troublesome as the internal timeout framework has changed a bit and
>>>> we would have to backport this too. I would pledge for the use of the
>>>> 1.4.0 development tree. What do you think about this?
>>> We always seem to be waiting for the next version of lwIP. :-)
>> True, true. But, with the original 1.3.2 lwip code, ppp can only be used
>> in a multi-threaded environment. I'd have to adapt the CDL etc. for the
>> vanilla 1.3.2 codebase and could not use it in my own projects. So this
>> effort seems kind of useless, at least to me. Moving on to 1.4.x would
>> solve the issues quite nicely. We would get updated ppp code, with full
>> support for usage in both single and multi-threaded environments. All I
>> say is, I'd rather invest some time moving forward than moving backward
>> :) But I certainly see your point here, it's been a long time already ...
>>
>>> At this stage, I would favour an initial check-in of something close to
>>> lwIP 1.3.2 followed by an update of the PPP code from the lwIP HEAD as
>>> time permits.
>> So you would like to import my changes to ppp? As said above, I don't
>> really want to go back to the original 1.3.2 ppp code myself.
>> I plan to upgrade my own application to lwip 1.4.x soon and get the
>> remaining changes of my ppp code (mostly 'record' support for debugging
>> ppp connections using wireshark) upstream. Of course, when we have 1.3.2
>> in the eCos repository, I could provide patches for the upgrade to 1.4.x.
> 
> OK. I've taken a look at src/netif/ppp/ in the upstream CVS HEAD. There
> are, indeed, a lot of changes. I appreciate that you do not want to put
> effort into unpicking your own PPP-related changes for the initial
> check-in. I do not want to delay the check-in further, so the remaining
> options are:
> 
> a) Check-in src/netif/ppp/* from upstream lwIP 1.3.2 for now and warn
> eCos users that lwIP PPP is not yet supported. We could remove the
> PPP-specific CDL items for to avoid confusion. People who want to
> experiment with lwIP PPP immediately can still fetch your tarball to
> make use of your current PPP changes.
> 
> b) Check-in src/netif/ppp/ from your contribution. We would have to
> advise eCos users via CDL display strings and comments that the PPP API
> and underlying functionality is non-standard and subject to significant
> change in the near future. May be just append " (experimental)" to the
> display string for CYGPKG_LWIP_PPP and mention that this feature is
> "subject to alignment with the lwIP 1.4.x API" in the description string.
> 
> Having thought long and hard about this, I'm reasonably comfortable with
> option (b) so long as we're all clear that the PPP implementation is
> non-standard and will be replaced by something closer to the upstream
> sources. It does not seem right to reject a well-tested lwIP PPP
> implementation in favour of ... nothing usable.

Well, I'm fine with that. Over the weekend I did initial work of an lwIP 
1.4.x port. I think by the time of an official 1.4.x release, I will be 
able to provide an updated port for eCos. In the meantime, people can 
use the 1.3.2 port.

> One other minor issue I've just noticed. Could you add
> CYGPKG_NET_LWIP_CFLAGS_ADD and CYGPKG_NET_LWIP_CFLAGS_REMOVE CDL options
> for manipulating the compiler switches in line with the majority of
> other eCos packages please?

I added the CDL options and also marked PPP support as "experimental", 
as suggested. The new tarball is at:

http://download.westlicht.ch/lwip-20100125.tar.gz

Best regards
Simon