More DFE-570TX Tx Hung Problems

[Donald Becker]

On Tue, 18 Apr 2000, Tim Dixon wrote:

> > > When they do occur, it's quite drastic because an ifconfig up/down
> doesn't
> > > restore the interface to working order, only a hardware reboot does the
> job
> > > (which tends to inconvenience people attached to other ports!).
> >
> > Hmmm, that's an important point.  Are you using modules?  If so, so
> removing
> > and reinserting the module restore operation?  (I suspect not.)
> 
> Haven't tried that, as I say, it's a once a fortnight bug, so it may be a
> little while
> before I get round to finding out.
> 
> > Do any of the interfaces on the 4-port card work when this happens?
> 
> Well (and this is where it gets more interesting), some of the cards are
> sharing IRQs (there aren't enough to go around....). When we have this
> problem two interfaces on two separate cards usually go down together - two
> interfaces that share the same IRQ. However, a third interface (which also
> shares the same IRQ) seems to get along fine...

This is *very* interesting.  It shouldn't happen.  If the interrupt is
getting through, all handlers on the IRQ chain should be called.

An implication of the behavior is that a card with a "broken" interrupt
setting (usually a four-port card with a mis-assigned interrupt) might
still appear to be functional as it's effectively being polled by the
interrupts being generated from the other devices on the IRQ.

You can test this by trying each device in turn, while leaving the other
devices idle and thus not generating interrupts.

Donald Becker				becker@scyld.com
Scyld Computing Corporation
410 Severn Ave. Suite 210
Annapolis MD 21403


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