Re: xen and networking problems

[brook%biology.nmsu.edu@localhost (Brook Milligan)]

Manuel Bouyer writes:
 > Did you check with tcpdump on the remote end that the remote end is
 > getting the ICMP echo request sent by the fxp adapter when ping is
 > running ? That would confirm that transmit is working.

The remote end is seeing (and responding to) arp requests from the xen
machine.

 > For receive, you could add a printf to check that in fxp_rxintr,
 > the code does call (*ifp->if_input)(ifp, m);
 > If it does not, the next step is to add more printf in fxp_rxintr to
 > see at which point the packet is dropped (there are many places for this,
 > basically each time that FXP_INIT_RFABUF() is called.

With more instrumentation it is clear that fxp_rxintr is exiting
immediately.  The value of rfa->rfa_status (and thus rxstat) is always
0 on entry to the function.  Consequently, the early checks cause an
immediate exit.

So, it seems that transmission of packets is ok but incoming packets
are never seen by the driver because their status information is
wrong.  Does this imply that the hardware is not providing the correct
information (it does fine without xen) or that xen is interfering in
some way?

What is the next step to debugging this?

Thanks again for the help.

Cheers,
Brook