Subject: "ex" or "exphy" media selection hosed?
To: None <>
From: Thor Lancelot Simon <>
List: tech-net
Date: 06/01/2000 16:10:56
We have a number of machines here which have various flavors of 3c905 in
them.  In particular, we have several new Dell machines with onboard
3Com chips, and one machine with a 3c905-TX-NM card whose phy is not
recognized by "exphy", or wasn't last I checked.  The onboard 905's
PHYs do in fact match exphy.

A few of these machines are connected to 10baseT hubs.  With "media 10baseT"
on the initial ifconfig, these do work.

The machine with the -TX-NM card with the "ukphy" on it is connected to
a Cisco 3524 switch, on a port set for automatic media negotiation.  It
*only* seems to work if I put "media 100baseTX" on the initial ifconfig
command line -- note that the switch and port *do* support both Nway and
full duplex, but these don't seem to work.

The machines with the onboard 3c905 don't work when connected to the
Cisco switch *at all*.  And the way they don't work is really, really odd:
an "ifconfig -a" at boot time shows that the driver has correctly
negotiated 100baseTX-FDX with the switch, but as soon as I actually do *any*
ifconfig operation on the interface, whether I specify a media option or
not (including "media auto", "media 10baseT", and "media 100baseTX" and
"media 100baseTX-FDX") the interface goes from "active" to "no carrier"
and if I've left it in "auto" mode the previous autoselection of 
100baseTX-FDX goes away, too.  Also, there's a brief system hang when
I do the first "ifconfig" (the one that hoses everything) though subsequent
ifconfigs, including attempts to explicitly set the media, don't do this.

I suspect "ex" or "exphy" is screwing up Nway negotiation somehow, either
with newer "ex"/"exphy" devices or just in general.  Has anyone got an
"ex", in particular a new-ish one, working correctly with a modern Cisco

I haven't built an INSTALL kernel with no "exphy" yet to check if "ukphy"
will at least let me hard-wire the media selection and not lose carrier.
Details at 11. :-)

Thor Lancelot Simon	                            
	"And where do all these highways go, now that we are free?"