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

[Jan Wester]

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

To: Mailing list for lwIP users

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.

file://Jan

-----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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