The point: if you have odd problems with your new computer, check for IRQ conflicts.
That’s been good advice for, what, twenty years? Anyway, I forgot it. Here’s what happened in case you’re as clueless as me.
I put together a new server for my “data center” — in the corner of the basement near the washer and the spare bicycle wheels. It’s spec’ed more or less from the Ars Technica mid-level system guide: Asus motherboard, AMD 64 CPU, SATA drives. I put FreeBSD on it.
Or, I tried to. Everything worked fine until I rsync’ed backup files from the old server, then boom! kernel panic and reboot. OK, I Googled about and learned that the ‘nfe’ network driver is recommended over the default ‘nve’ driver. Fair enough. That seemed to work better, though I still had many Ethernet transaction errors and watchdog timeouts. My connectivity was laggy and prone to drops.
My hub was 10BaseT only. I think I bought it right after I cancelled my Compuserve account. I replaced the hub with a nice Gigabit switch, and everything was great.
Well, better. It bugged me that my NIC only worked without the reccomended patch. I still saw an occasional warning in the log. And my SSH sessions dropped more than they should. I tried an old 100 MHz PCI NIC, and that worked, so I figured it was just bad hardware. I looked for something better than the onboard Intel NIC. Turns out, the onboard NIC is regarded as a good one, and when I tried another brand, it didn’t work at all.
At this point, I decided to live with the situation. That was OK until I installed Gnome so that I could run nightly Selenium tests. Boom. Panic every night when network backups started. I switched out the DSL router. I moved the server next to the router and replaced the 50-foot “data center” cable with a new short one. I removed all other computers from the wired network.
More panics. Hundreds of oversize frame errors n startup. Not just slightly above MTU size, but like 10,000. Huh?
At this point, I considered donating the motherboard and RAM to FreeGeek and just sucking it up and replacing all of it. I when through the messages log carefully and there it was: USB and NIC on the same IRQ.
My theory is that some Gnome-related daemons probe the USB ports, and this was interpreted as Ethernet traffic. I obvioulsy don’t really know crap about hardware though. In any case, I disabed USB in the BIOS and nary a problem now.