usb keyboard dying at loader prompt
avg at icyb.net.ua
Wed Nov 12 03:29:18 PST 2008
on 11/11/2008 20:55 Peter Wemm said the following:
> Some bioses have a list of MBR partition id's and use that to
> determine what to do with the USB keyboard. One of my ol older amd64
> motherboards worked but would always disable the usb keyboard right as
> loader started. I discovered the following:
> * If I put the freebsd bootblocks and loader on a floppy drive (no
> MBR), then the bios did not turn off the keyboard. It always
> continued to work for loader.
> * If i hacked the boot bootblocks and loader and kernel to recognize
> different MBR slice id nubmers as "ours", then changing the freebsd
> MBR to be "msdos" or "linux" also worked for that BIOS. It would no
> longer turn off the USB keyboard. I don't recall which Id number I
> used instead of 165 - it was about 4 years ago.
> * There were other consequences of using the partition ID hack - I
> think I remember it turning off the apic for msdos mode.
> Your problems may be different, but mine were caused by a BIOS
> whitelist of MBR partition id's. What a stupid problem. On that
> motherboard I ended up taking the path of least resistance and using
> the PS/2 adapter plug on the keyboard.
Foul play on BIOS part is definitely a big possibility.
What puzzles me most is random/inconsistent behavior from boot to boot.
Maybe there is some misalignment between how BIOS emulates legacy
keyboard and how our boot chain interacts with it, some timing issue or
Anyway, this is very hard to debug or guess. Most probably I will have
to live with it (this system doesn't have PS/2 ports at all).
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