Re: [lwip-devel] Bug in Checksum implementation and ARP fix

[Leon Woestenberg]

Hello Paul, Kieran,

> > There is a bug in the implementation of lwip_chksum.
> > Basically it assumes that you can perform 16 bit access on
> > non 16 bit aligned address
> >
> > The offending line is
> >
> >     acc += *(u16_t *)dataptr;
> >
> > This is not valid on all processor architectures.
>
Funny. We had a local patch on this. I assumed our compiler was the problem,
but the cast to a u16_t makes dataptr required to be on a 16-bit boundary,
right?

> break some architectures too.  Maybe we should move the checksum code into
> an architecture specific place in the source tree, and keep a
> generic-should-work-on-most implementation (ie. the one there is
> already) as the default.  Anyone got opinions on this?
>
Yup. Could we do it the same way as we handle htonl() etc? I think
we used macro's there.

> >           for (k = 0; k < netif->hwaddr_len; ++k) {
> >             ethhdr->dest.addr[k] = ethaddr->addr[k];
> > >>>>>            ethhdr->src.addr[k] = netif->hwaddr[k];
> >           }
>
Thanks, good bug hunting!

> > Lastly does anyone know how to get CVS write access. I would
> > like to add in a new architecture port?
>
No problem, finding two bugs qualifies you for CVS access :-)

BTW, I am very interested to hear which architecture you have ported
to. Wouldn't that be Altera's NIOS?

Please email your Savannah ID and I can add you to the cvs committers.

Please make sure to make changes solely in the DEVEL branch!

> I'll let Leon answer this one.  I'll be interested to see what the
> architecture is - it's good to hear that a company like Altera is using
> lwip.
>
We already had Xilinx on the list, so a bit of competition is never bad :-)

> > P.S. I can send patches in diff -u format if required
>
> In general, that's useful, but for fixes as small as this probably
> overkill.  Easiest thing to do is send mail (as you have done) and submit
> a bug report on savannah to ensure it doesn't get forgotten about.
>
Fully agreed.

Regards,

Leon Woestenberg.