Subject: Re: sysinst, two more notes
To: None <jonathan@DSG.Stanford.EDU,>
From: Wolfgang Solfrank <>
List: current-users
Date: 02/17/1999 12:27:37

> > No.  We should *never* over-write existing MBR code, unless the user
> > explictly asks for that to be done.  (the only reasonable exception of
> > updating MBR code that we know is old NetBSD MBR code, preserving the
> > MBR partition table.


> Well, I just installed NetBSD 1.3.3 on a system that had NetBSD 1.3_BETA
> on the disk.  I picked the default settings in sysinst and install went
> OK - but guess what?  It doesn't boot off the hard disk!

Hmm, there is _no_ difference between the 1.3_BETA and the 1.3.3 mbr
code (installed by fdisk).  The NetBSD boot code (installed by installboot)
in 1.3.3 understands the new NetBSD partition ID (169) and has a minor
difference in the fake partition table (which doesn't matter as you would
have to use special parameters during install to use this).  None of
these changes should affect your being able to boot or not (the ID
change will warn about the old ID, but that doesn't hurt).

Given the above, I would have liked to see a copy of the start of the disk
in order to analyze the problem further.

Assuming you could boot 1.3_BETA from that disk, and the 1.3_BETA install
was also an install using the default settings, what was the exact problem
of not being able to boot?  Did it show anything on the screen during your

> I erased the first sector of disk and did "installboot...", still no boot.
> Now I'm installing again from scratch after erasing a few megabytes of
> the disk.

Did you erase the first sector of the disk, or of the NetBSD partition?

The former is the one containing the mbr and isn't rewritten by installboot.
It is written by fdisk.  Running "fdisk -i ..." would have overwritten it
with new mbr code (independent of whether there was any code there before),
however, it would have also installed a fresh (mbr) partition table,
which might or might not coincide with your original one.  (This is fixed
in -current, BTW).  Using fdisk to modify the partition table in any way
would also install mbr code if the mbr isn't valid before.

The first sector of the NetBSD partition is the one that installboot
overwrites (among others). (BTW, there is no need to erase anything
before running installboot).

Anyway, since you seemded to have erased the mbr code, but failed to
reinstall a new one, not being able to boot *after* that procedure is
to be expected.

ws@TooLs.DE     (Wolfgang Solfrank, TooLs GmbH) 	+49-228-985800