How to debug PCI issues?

[Ben Greear <greearb@candelatech.com>]

I'm working with a TYAN Tomcat board (i815, Ghz CPU).  It's in a 1U
machine with a butterfly riser so that I get two riser connections to
one PCI slot.  When I put Intel EEPRO nics in each slot, I can pass
30Mbps of traffic on each NIC without dropping a single packet
(In two days of running).

If I run 20Mbps on one of the DLINK ports, I'm fine, but if I run 10Mbps
on two of the DLINK ports, I start seeing dropped packets on every
interface, and port errors like RX-FIFO.

So, I'm thinking that the DLINK NIC must be screwing up the PCI
bus somehow when more than one of it's interfaces is passing any
significant traffic.  I have been able to run 10Mbps on all 8 ports
of two DLINKs on an Intel EEA2 (i815) board, so I suspect the MB.

Does anyone have any ideas how to go about trouble-shooting this
farther?

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>          <Ben_Greear@excite.com>
President of Candela Technologies Inc      http://www.candelatech.com
ScryMUD:  http://scry.wanfear.com     http://scry.wanfear.com/~greear