I have a MacPro3,1 that I've recently upgraded to High Sierra using the patch. I also still use an older 1st gen 64GB iPod Mini (yes, upgraded) that I've always connected to the machine via the FireWire 400 cable. Up until I did the High Sierra upgrade, the Mac and iPod had no issues.
If I plug the iPod into the Mac with the FireWire cable the screen immediately dies and the Mac reboots. If I leave the iPod plugged in, the computer will go into a continuous reboot loop (several seconds in between). I did notice in one of the generated Apple problem reports that it is a FireWire related kernel panic.
Any ideas why this would be happening? Is FireWire no longer supported on High Sierra perhaps?