Subject: Re: fxp card causing freeze on netbsd 2?
To: Stuart Brooks <>
From: Steve Woodford <>
List: tech-kern
Date: 04/18/2005 10:01:13
On Monday 18 April 2005 08:21, Stuart Brooks wrote:

> I have a Netbsd 2 machine with an Intel SB82558B chipset network card
> which has frozen a couple of times. The interesting thing is that the
> network card is going mad but everything else has locked up.

I've also seen this with fxp(4). In my case it happens when the kernel 
stops servicing Rx interrupts (while in ddb, for example). When the card 
fills the remaining Rx buffers it starts flooding the wire with 
flow-control packets (as evidenced by your tcpdump) which can swamp the 
upstream switch to the point where all other traffic on the switch is 
blocked (I've observed this behaviour on several flavours of switch).

An easy way to provoke this bug is to drop into ddb, then ping the 
machine until the fxp's Rx buffers are exhausted.

Cheers, Steve