lwip tftp not working on imx8mm

[Tim Harvey]

On Mon, May 26, 2025 at 5:17 AM Jerome Forissier
<jerome.forissier at linaro.org> wrote:
>
> Hi Tim,
>
> On 5/23/25 20:31, Tim Harvey wrote:
> > Hi Jerome,
> >
> > I've enabled LWIP on imx8mm_venice to see how it's doing and while
> > dhcp/dns/ping/wget appear to work great, tftp is broken.
> >
> > Enabling LWIP_DEBUG shows the following:
> > ip4_input: packet accepted on interface et
> > IP packet dropped since it was fragmented (0x2000) (while IP_REASSEMBLY == 0).
>
> Hmmmmm IP_REASSEMBLY should probably default to 1.
> >
> > I tried enabling IP_REASSEMBLY in lwip but that seems to change the issue to:
> > ip4_input: packet accepted on interface et
> > ip4_input:
> > IP header:
> > +-------------------------------+
> > | 4 | 5 |  0xc0 |       108     | (v, hl, tos, len)
> > +-------------------------------+
> > |    10568      |000|       0   | (id, flags, offset)
> > +-------------------------------+
> > |   64  |    1  |    0xe25b     | (ttl, proto, chksum)
> > +-------------------------------+
> > |  172  |   24  |    0  |    2  | (src)
> > +-------------------------------+
> > |  172  |   24  |   21  |  251  | (dest)
> > +-------------------------------+
> > ip4_input: p->len 108 p->tot_len 108
> > Unsupported transport protocol 1
> >
> > Any ideas what the issue is here?
>
> Not really :-/ Does the transfer work with a smaller block size?
> (CONFIG_TFTP_BLOCKSIZE, default 1468, try 500 for instance). You could
> also enable CONFIG_LWIP_DEBUG_RXTX in order to get a full hex dump of
> the messages going into/out of the lwIP stack.

Hi Jerome,

My config was with 4096, setting it to 1468 works and anything above
that seems to cause this failure.

Some sort of fragmentation issue?

Best Regards,

Tim