Strange problem with sk0

[Pyun YongHyeon]

On Fri, Oct 22, 2010 at 05:09:33PM -0400, Mikhail T. wrote:
>  Hello!
> 
> I have a rather bizarre problem with my on-board sk interface... It only 
> works, when tcpdump is running...
> 
> Seriously. It negotiates with the switch (1000baseT/full-duplex) just 
> fine, but, unless tcpdump has it open (and in "promiscuous" mode), no 
> traffic seems to go through. It would not respond to pings -- not even 
> from the switch itself, nothing.
> 
> But, as soon as I start tcpdump -- even if tcpdump never has anything to 
> output:
> 
>    tcpdump -i sk0 -n src host 10.non.existent.IP
> 
> Traffic starts flowing just fine... Do I simply have flaky hardware? The 
> motherboard is old, and, for some reason, I need to "remind" sk0, what 
> its ethernet address upon reboote (it starts off with 00:00:00:00:00:00).
> 

The all 0 station address is clear indication of source of problem.
Normally ethernet controllers drop frames not destined for the
station address unless promiscuous mode is activated. tcpdump is
one of program that activates the promiscuous mode.

To narrow down the issue, show me the output both dmesg and
pciconf -lvcb.

> Any other explanations for what is happening? There are plenty of other 
> systems (computers, VoIP phone, two TVs) on this switch and all are 
> fine... I did try different ports on it -- same results. I also tried 
> forcing things down to 100/half-duplex -- no change...
> 

It seems sk(4) failed to extract station address from controller so
I have to know why it happens on your box.

> Thanks! Yours,
> 
>    -mi