Re: R: [lwip-users] ip_reass

[Ed Sutter]

Ok, I am running with the BF537, I'll take a look at that setting.
However, it still seems to me that this is a problem in the code
because the combination of...

  1. MEM_ALIGNMENT = 4
  2. pbuf_alloc() setting payload buffers up to be aligned based on 
MEM_ALIGNMENT
  3. the increment of the payload pointer by 14 in ethernet_input()
and...
  4. the overlay of the "helper" structure in 
ip_reass_chain_frag_into_datagram_and_validate()

will cause the misaligned access.  If the option you mention fixes it for my
situation on the BF537, that doesn't resolve it for other systems.
Right?
Ed

Ceresoli Luca wrote:
> Ed Sutter wrote:
> > I'm running LWIP 1.3.0 on a Blackfin, which is picky about 
> > ...
> > The ethernet_input() function then sees that it is IP, 
> > increments the payload
> > pointer by 14 (size of ethernet header) and passes the pbufs 
> > to ip_input().
> > Note that at this point, the payload pointer is no longer 
> > aligned on a 4-byte
> > boundary because the original 4-byte-aligned payload pointer 
> > is incremented
> > by 14.
>
> Which Blackfin are you using?
> Tha Ethernet MAC of Blackfin 536/7 can optionally add two dummy bytes in front 
> of incoming frames (setting bit RXDWA in the EMAC_SYSCTL register). This makes 
> all TCP/IP headers 4-byte aligned.
>
> Of course your driver must support it.
>
> Luca
>
>
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