Excerpts from netbsd: 15-Dec-97 Re: installboot doesn't see.. Paul
Newhouse@nas.nasa.g (1323)

Some clarifications:

> >>   /usr/mdec/installboot -f /usr/mdec/biosboot.sym /dev/wd0a
> >How about /dev/rwd0a ?
> 
> I'm pretty sure I tried that it did the same thing.

It should only work with the raw device.
With the block device, it should result in an error message
"bad device name".

> >(I'm assuming that you used "fdisk /dev/rxd0d".)
> 
> I believe I tried all combinations.

"/dev/rxd0d" is the only right thing to do. (except you play
games with extended partitions)

[fdisk gives "junk"]
> > It is OK if you have assigned the whole disk to NetBSD.

You should get at least a partition table with a NetBSD
partition. If you start the NetBSD partition at 0, you get
the default table from "biosboot.sym" which contains
a fake geometry. But the partition should be there in any
case.

> read about the boot blocks going on the first track and I just got in
> the habit of leaving  it unassigned

That was and is unnecessary. The bootblocks use
the first 15 disk blocks (a 512 byte) only, this space
is left free by the filesystem.
If the NetBSD partition is started at the second track,
this has other reasons - the stupid BIOSes I mentioned
in an earlier mail and the ability to install a generic
boot selector.

> I've also noticed that
> biosboot.sym seems to be larger than 63 secotrs that might have
> something to with the problem?

"biosboot.sym" still contains the symbol table, so the
net size is smaller. You get the exact size if you use
the "-v" option of "installboot".
As I said, only 15 sectors are used at the beginning of the partition.
The remainder goes into the file "/boot" now. 
A difference between the old and the new behaviour if that
the old "disklabel" install read the BIOS partition table and put
the bootblocks at the beginning of the NetBSD part as defined there.
The new "installboot" uses the NetBSD partition table and
puts the said 15 sectors at the beginning of the partition specified
at the command line (usually 'a').
In standard setups these offsets are identical, but in your
setup, where the BIOS partition table didn't point to the
beginning of the NetBSD bootblocks, this went wrong.

best regards
Matthias