Greg Hudson <ghudson@MIT.EDU> writes:

> > So I don't believe we use these numbers for anything.
> 
> Once you have a booted system, it doesn't matter; you have a real
> disklabel and you're done.  But if you're the install procedure, you
> definitely do use those numbers: they show up as the disklabel
> geometry when you run fdisk.  So if a user creates a NetBSD partition
Yes, this is the only thing it is needed for.  You must know the BIOS
geometry to calculate the C/H/S for the start of the NetBSD partition

> with something like pfdisk, and then runs the install script, one of
> the suggested geometries is through the roof because the cylinder
> geometry has been translated to the LBA geometry but the number of
> cylinders didn't change accordingly.
I fixed this in disklabel, but Charles unfixed this, because of 
gratuitous printouts.  You divide the secperunit by the new H/S and
all it well.

> 
> Of course, arguably the install script should just make up something
> out of whole cloth for the disklabel it installs, unless the user
> intervenes.  Then the previous disklabel geometry would be irrelevant.
> (You don't want to use the BIOS geometry for the disklabel because FFS
> will typically demand something like 4K fragments if it thinks you
> have cylinders that huge.)
Exactly.