Re: [lwip-users] Hardware Assisted Checksum

[Kieran Mansley]

On Wed, 2005-11-23 at 11:02 -0800, Jim Gibbons wrote:

> It is common these days to have TCP/UDP/IP checksum assistance in
> ethernet interface chips.  This is a very appropriate place for the
> checksum, since everything is ready for checksumming by the time it
> gets to the chip.

Yes - doing it in hardware *after* the TCP stack has fragmented it makes
a lot of sense.  As I interpreted the original question though they were
hoping to do it in hardware *before* the TCP stack processed the data.

> If lwIP allowed checksumming services to be performed at the driver
> level or beneath, then systems having special hardware - either in the
> ethernet chip or some other FPGA - could be used.

I think this comes into the role of porting to a particular
architecture.  As has been mentioned recently, the lwIP checksum code is
unlikely to be optimal on many systems, and so is a candidate for
improvements when porting, but it would be hard to optimise it further
in a generic way.

Kieran