I just upgraded a '486 from NetBSD 1.2 to 1.3, letting sysinst upgrade
the boot blocks but unpacking the distribution tar files by hand.  The
upgrade went fine except for one disturbing incident: after the boot
blocks were upgraded, the machine refused to boot from the hard disk.
It simply hung at a very early stage in the boot process, before
printing any messages at all.

Fortunately, I was able to remedy the situation by installing OS-BS.
My theory as to what happened is as follows:

The IDE disk in question is divided into several MBR partitions,
including a small MSDOS partition and the NetBSD partition.  Despite
the multi-OS nature of the installation, I did _not_ have a boot
selector installed; I am in the habit of booting MSDOS from a floppy
on those rare occasions when I need it.

The sysinst upgrade procedure upgraded the boot blocks at the
beginning of the NetBSD partition, but it did not touch the MBR.

I believe my MBR actually contained a NetBSD stage 1 boot block,
possibly from NetBSD 1.0 or 1.1 (I can supply a copy of the MBR in
case some MBR taxonomist would like to try to identify it).
This MBR was able to boot NetBSD 1.2 just fine, but was apparently
incompatible with 1.3.

Was my setup somehow strange, uncommon, or even incorrect, or has
anyone else run into the same problem?
-- 
Andreas Gustafsson, gson@araneus.fi