[U-Boot] u-boot tftp problem

[PF4Public]

Hello, Joe

 >Can you provide more exact details on the servers you are trying including versions?
 >Perhaps also provide pcap files (not text dumps) so the exact packet contents can be 
observed?

Recently I've done some tests, hope you find them interesting.

Server in question:
Linux sterver 3.2.0-4-686-pae #1 SMP Debian 3.2.65-1+deb7u1 i686 GNU/Linux
  r8169 0000:08:04.0: eth1: RTL8169sc/8110sc at 0xf827e000, 90:e6:ba:07:3e:a5, XID 
18000000 IRQ 19
ii  tftpd                             0.17-18 i386                  Trivial file transfer 
protocol server

I have mirrored 2 ports at the switch. Here's what I have found:
1. tftp block ack packets have some extra bytes. They are "mage octet tim". Suppose that's 
because buffer reuse in u-boot after "uImage octet timeout 5", although I'm not so sure.
2. u-boot never generates wrong block acks if "#define TIMEOUT     8000UL". Obviously 8 
seconds is enough for tftp server to resend the block, so with this define, it is not 
timing out and keeps downloading till the end. Ofcourse it just masks the real problem, 
nothing more.
3. at the times of server resending block it is u-boot who lost the packet. I believe that 
if the packet was delivered to mirrored port, it must have been delivered to u-boot. But 
logging at u-boot shows no evidence of packet reception, however packets following missed 
one are registered.
4. the only condition at which u-boot didn't loose packets and downloaded uImage without 
timeouts was when I made it log everything regarding network. this gave enormous output to 
console, but no tftp packets lost. Even though I tested it twice it could be a coincidence.

Also I tried disabling caches. Rebuilding with "CONFIG_SYS_ICACHE_OFF" and 
"CONFIG_SYS_DCACHE_OFF" was no difference at all. At least for tftp download.

I was about to provide you with pcap files from mirror port and corresponding u-boot 
console log, but sadly seems that I have deleted u-boot log by mistake :( I think I have 
to repeat the whole thing before I can provide you with them both.

Best regards