Re: [lwip-users] TCP behaviour with Zero Copy API using Raw API interface

[Peter Jolasson]

Hi again,

To correct myself.
It's not when there is an odd number of bytes to transfer that it fails.
It fails when the data is located at an odd address.

But as said before my workaround is to set "copy" to 1 and then it works OK.

My target cpu is ARM and I've set MEM_ALIGNMENT to 4.
//Peter

On 6/8/05, Peter Jolasson <address@hidden> wrote:
> Hi,
> 
> I dont have a solution to your problem but I can describe a 'funny' behavior
> that I've noticed with tcp_write().
> When I send an even number of bytes I can set "copy" to 0.
> But when sending an odd number of bytes I must set "copy" to 1 otherwise
> it will fail.
> 
> I'm using lwIP 1.1.0
> //Peter
> 
> On 6/7/05, Sathya Thammanur <address@hidden> wrote:
> > Hi all,
> > I have a client program that connects to a server on PC. The client is
> > a simple program that sends data to PC. What I notice is that when I
> > call  tcp_write() with "copy" argument 1, then my program works
> > without any issues. However, if I change "copy" to 0 then I notice
> > that the TCP connection is not established completely. The following
> > happens :
> >
> > Client                            Server
> > SYN ---------->
> >       <---------             SYN, ACK
> >
> > Junk packet sent from client. The Server resends the SYN, ACK and then
> > closes the connection. TCP client sends a lost ACK with incorrect
> > sequence number after couple of junk packets.
> >
> > I do notice that my application call back that is registered with
> > tcp_connected() is called. Here is where I start to send data. I am
> > using lwip version 0.7.2.  Am I using the tcp_write() in the right way
> > as intended ? Any correct usage of this function will be very useful.
> >
> > Any help would be greatly appreciated.
> >
> > Thanks,
> > Sathya
> >
> >
> > _______________________________________________
> > lwip-users mailing list
> > address@hidden
> > http://lists.nongnu.org/mailman/listinfo/lwip-users
> >
>