Re: [lwip-users] etharp_output: could not allocate room for header.

[Simon Goldschmidt]

The most obvious reason would be that the pbuf you have passed to udp_send() 
was not allocated using PBUF_TRANSPORT and thus does not provide enough room 
for all headers.

Simon

> Hi all,
> 
> I'm trying compile an little application with lwip inside ecos. Here is 
> the trace of my program:
> 
> udp_send: added header pbuf 0x20174fd4 before given pbuf 0x20176ad4
> udp_send: sending datagram of length 55
> udp_send: UDP packet length 55
> udp_send: UDP checksum 0x3bd5
> udp_send: ip_output_if (,,,,IP_PROTO_UDP,)
> pbuf_header: old 0x20175008 new 0x20174ff4 (20)
> ip_output_if: et1
> IP header:
> +-------------------------------+
> | 4 | 5 |  0x00 |        75     | (v, hl, tos, len)
> +-------------------------------+
> |        0      |000|       0   | (id, flags, offset)
> +-------------------------------+
> |  255  |   17  |    0x5657     | (ttl, proto, chksum)
> +-------------------------------+
> |  172  |   16  |    6  |   43  | (src)
> +-------------------------------+
> |  172  |   16  |    6  |  255  | (dest)
> +-------------------------------+
> netif->output()etharp_output: could not allocate room for header.
> 
> After that, the application crashed. Anyone knows why ?
> 
> 
> Thanks for your helps.
> 
> NT
> 
> 
> 
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