Just thought I would share a discovery with the community about the 
Lite-On 82c169 PNIC.  I'm working on a tulip driver for darwin (using Bill 
Paul's freebsd "dc" driver as a reference along with Jason Thorpe's netbsd 
"tlp" driver) and thought I would document one of the PNIC's stupid bugs.

When transmitting a setup frame, it will underrun EVERY TIME if the link 
is in a failed state (CSR6 bits 4 and 12). If the link is confirmed to be 
in a good state before tx'ing the setup frame, all goes as planned.  This 
took me over a week to figure out (and I'm somewhat ashamed to admit it...
  :-)

Very few of the PNIC's eccentricities are documented anywhere I figured I 
would add to the collection of wisdom out there so future google searches 
will actually help.

cr

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see the driver at http://sourceforge.net/projects/darwin-tulip/