> F1-F4 no longer work.

Are you certain it is NetBSD's fault?

I had a system with 2 SATA drives, and the F1-F2 worked fine.
Then I added 2 more drives, and the <expletive> pee-cee quality
firmware got confused and now F1-F4 no longer work.

I even pulled the jumper to reset the firmware to all
factory defaults but it didn't clear this problem.

My workaround:

The drive that the firmware boots comes up in grub.
The grub boot menu has entries for each drive.
I don't know what is different between NetBSD's MBR booting
a drive and grub booting a drive, but it works.

I have shell scripts that change the default in the
grub boot menu and then reboots, so I can type

# boot_freebsd

and it works.