can't mount root during freebsd-update 7.0 -> 8.1 on amd64

[perryh at pluto.rain.com]

"Andrey V. Elsukov" <bu7cher at yandex.ru> wrote:
> >> NOTE: Some old utilities like bsdlabel may not work if the
> >> kernel doesn't include GEOM_BSD and other old slicer classes.
> >> In other words, bsdlabel et al don't work with GEOM_PART.
> > 
> > Does this mean that, in 8.1-RELEASE, bsdlabel/disklabel will
> > not work with the GENERIC kernel (which includes GEOM_PART_GPT
> > and GEOM_LABEL, but no other GEOM_ pieces AFAICT)?
>
> No, It doesn't. You can create partitions with fdisk/bsdlabel.
> They do write directly to device and this does initiate tasting.
> And GPART detects created partitions.

Thanks, that's what I had hoped (but had noticed a few things lately
that had me wondering whether they might perhaps not be working
entirely _correctly_ -- I need to do some more experimentation).

The next question then is, when _does_ the kernel need to include
added options like GEOM_BSD and/or GEOM_PART_BSD?