Re: [lwip-users] Help with IP header size

[Luca Ceresoli]

Adam Fullerton wrote:
>    Hi,
>    I am trying to make lwIP work with a big endian SH processor, but I
>    think that I have some of the configuration options set incorrectly.
>    The processor is 32 bit and the DMA requires the data to be 4 bytes
>    aligned.
>    When I look at the data sent by a DHCP discover it has a two byte
>    offset at the start:

Check the ETH_PAD_SIZE option in your lwipopts.h file, and the docs in
opt.h.

That option is used to improve performance on 32-bit systems. It's
probably something that you want to have, but your Ethernet device
driver must be written accordingly.

Luca