Half of the devices were just powered by USB and not using any data, but only needed to be ON when the PC is ON.
The way it worked:
- FreeBSD would scan all USB devices
- get held up on some for no reason
- find a hub
- scan everything on a hub
- find another hub
- scan everything on that hub as well
Anytime during the scan it could run into a device that takes longer (no clue which or why, only happened on FreeBSD and never on Linux or Windows)
I'm sure windows and linux did the same thing, but both shapely continued booting while FreeBSD waited and waited and waited and waited.
Bias light on a monitor would sometimes completely stop the process until unplugged.
USB stack on FreeBSD is forever cursed, I still remember kernel panics when you unplug a keyboard or a mouse.
My understanding is FreeBSD will by default wait until it's found all the fixed disks before it figures out which one to mount as root. This could be a USB drive, so it needs to enumerate all the USB first. Adding hw.usb.no_boot_wait=1 to /boot/loader.conf.local or thereabouts if you don't need that will skip that wait and speed up the boot process a lot (especially on hardware where USB is slow to finish enumeration).