[lwip-commits] Porting LWIP into TI C6203 bug fix

[Amit Kristal]

Hi all,

I have been porting the lwip onto TI C6203 dsp.
The porting required a change to pbuf_alloc() & I believe I have encountered 
two bugs in the tcp->tmr & tcp->cwnd:

1. Changes needed in pbuf_alloc():

The DSP requires working 32bit aligned, meaning that memory should be 
alocated 32bit aligned & that ip_hdr / tcp_hdr will poitn to 32bit aligned 
addresses. YET the rthernet headr is 14 byte long... the solution was to 
work with MEM_ALIGNMENT= 4 & in pbuf_alloc() , in case of PBUF_LINK, after 
mem allocating, make payload point to a 16bit aligned adderss from which the 
ethrnet packet start, making the ip & tcp headers 32bit aligned in the mem.  
(PBUF_LINK_HLEN should be defined to 16)

2. tcp->tmr bug fix

I believe I have encountered a bug: tcp->tmr is 16bit yet tcp_ticks is 
32bit. (same problem may be with tcp->rttest). This means that after ~9.1 
hours the tcp->tmr will wraparound while tcp_ticks keeps on going... (this 
causes problems when calculating inactive times). the simple solution is to 
change tcp->tmr to be 32bit. (changing tcp_ticks to 16bit is more work since 
we have to handle the wraparound thet will happen after only 9 hours , with 
32bit it will take enough years...)


3. tcp-> cwnd bug fix on C60:
tcp->cwnd is overflowed in spite of the check:
 if(pcb->cwnd + pcb->mss) > pcb->cwnd) {
   pcb->cwnd += pcb->mss;
 }

Changing to

 if((u16_t)(pcb->cwnd + pcb->mss) > pcb->cwnd) {
   pcb->cwnd += pcb->mss;
 }

solved the problem.


Questions:

1. I get strange values when looking at stats.mem.used, is there a problem 
using it?

2. Is there anyone out there porting to c60?
3. Does Nagle algorithm currently implemented in the LWIP?
4. Which kind of tests do you recommend me to perform in order to be sure 
that my porting is successful?

Please comment on my findings above.

Thanks,

                      Amit

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