RE: [lwip-users] TCP checksum error for big sized packets on lwip 1.3.0

[Bill Auerbach]

I might think it would be easier to run native big-endian and fix whatever
has to be fixed to go that route.  Isn't it a lot easier to fix the new
big-endian problems than the deal with the existing little-endian alignment
problems?

Bill

> -----Original Message-----
> From: address@hidden
> On Behalf Of Jonathan Larmour
> Sent: Wednesday, May 07, 2008 8:39 AM
> To: Mailing list for lwIP users
> Subject: Re: [lwip-users] TCP checksum error for big sized packets on
> lwip 1.3.0
> 
> Muhamad Ikhwan Ismail wrote:
> >
> > Hi,
> >
> > I found out the problem already. My driver was set up to transfer out
> > one buffer per frame only (1520 bytes) since
> > we want to spare processing power as much as we can and also due to
> the
> > fact we have ample memory,
> > and the 1.3.0 seems to chain the TCP packets to form frames(multiple
> > buffers per frame). Is there any thing i can setup to force
> > TCP packs 1520 bytes per buffer (pbufs) ?
> 
> lwIP can chain pbufs, but the total size (pbuf->tot_len) should always
> be
> less than the MTU i.e. one packet. So if you get a pbuf chain to send,
> it
> should still be less than 1520 bytes. If your driver can only send
> packet
> data from contiguous memory, then you may need to copy the packet data
> into
> a special large buffer. You will only be able to handle one packet at a
> time then obviously.
> 
> Jifl
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