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SV: [lwip-users] Odd byte packets in LWIP


From: Jan Wester
Subject: SV: [lwip-users] Odd byte packets in LWIP
Date: Tue, 11 Nov 2003 15:13:06 +0100

Hi
We have also tested CS8900, we solved the problem by adding a 2k buffer to read out all payloads to and sened that to the controller.
You can't add space to you payloads, it corrupt your data
//Jan
-----Ursprungligt meddelande-----
Från: address@hidden [mailto:address@hiddenFör Nishen Naidu
Skickat: den 11 november 2003 13:00
Till: Mailing list for lwIP users
Ämne: Re: [lwip-users] Odd byte packets in LWIP

Hi,
 
I'm using a c8900 ethernet chip and I do know it
has a problem wit odd length packets.
Any idea what a solution to this problem might be?
Do you automatically make all the packets you send out even length?
I could not do this since the client on the other side requires the packet
length to be correct i.e. odd in this case.
The packets get sent out correctly if I make the packet even just before I call
the netconn_write, but I don't want to do it this way due to the above reason.
If I make the 'frame length' in the ethernet driver fot lwip even then the packets
still do not get send correctly.
Any ideas?
 
Thanks
Nishen
 
 
----- Original Message -----
From: Jan Wester
Sent: Tuesday, November 11, 2003 11:31 AM
Subject: SV: [lwip-users] Odd byte packets in LWIP

Hi
I had problem with odd length in the driver for Ethernet Controller, depending on the hardware how the Ethernet Controller is connected
to the processor.
We use ARM with Davicom Ethernet Controller.
We also got problem with odd startaddress for buffer, but I think what is ARM specific.
-----Ursprungligt meddelande-----
Från: address@hidden [mailto:address@hiddenFör Nishen Naidu
Skickat: den 11 november 2003 07:29
Till: Mailing list for lwIP users
Ämne: [lwip-users] Odd byte packets in LWIP

Hi
 
I'm having a problem sending out packets of odd length on certain occasions.
Does lwip work well with odd length packets?
I read the following comment in some lwip sample code:
/*
 
Important!!! LwIP data alignment issue:
   As of now LwIP code does not handle odd byte length packets properly. So round packets to even byte
   length by adding space characters (' '). This is true only for processors that cannot handle
   mis-aligned memory access.
 
*/
is this correct??
 
Thanks
Nishen


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