[lwip-users] Re: [lwip] Mem alignment problem

[Mumtaz Ahmad]

Well the mechanism of keeping 2 extra bytes extra  is helpful in sending any
packet and do align Ip header ,agree ,but what about the receiving packets ?
Packets  when recived do suffer memory alignment problem as the pbufs are
allocated from pbuf_pool and pool pbufs donot use this mechanism .

Regards
Mumtaz Ahmad
----- Original Message -----
From: Kieran Mansley <address@hidden>
To: <address@hidden>
Sent: Wednesday, March 13, 2002 7:32 PM
Subject: Re: [lwip] Mem alignment problem


> On Wed, 13 Mar 2002, Mumtaz Ahmad wrote:
>
> > Hi
> > I am  facing some troubles regarding memory alignment in lwip .I have
set my
> > memory alignment to 4 bytes .On incoming packet when etherheader
(14bytes)
> > is removed the payload pointer is set to startof ipheader . Obvioulsly
the
> > start address of ipheader is not 4 byte aligned . and my platform cannot
> > read integers from non 4 byte aligned address so the packets are
rejected at
> > IP layer .
>
> Most ethernet interfaces reserve two bytes in front of the packet so the
> ip header is aligned on a 16-byte boundary after the 14 byte ethernet
> header.
>
> Kieran
>
> [This message was sent through the lwip discussion list.]

[This message was sent through the lwip discussion list.]