I am about to install a new motherboard to recover a hardware
failure on an OpenBSD machine.  The old MB had an Intel based
CPU, however the replacement will support AMD64.

The old install was 4.0; obviously I wish to move to 4.1 at
this time as well.

I therefore want to migrate as much of the old setup as possible
to the new kernel, and I am looking for advice on pitfalls in
the two following strategies (and therefore which one seems the
most direct):

1) install the amd64 system onto the root disk as a new "install",
   (ie; from CD), moving over important config from a preserved copy
   of the current /etc and /var after the first boot.

2) move to amd64 by performing an "upgrade" _on top of_ the existing
   i386 system, performing the usual upgrade path "final steps"
   to get things going.

3) "upgrade" 4.0 i386 -> 4.1 i368, and then "upgrade"
   4.1 i386 -> 4.1 amd64


There are existing binaries on this system I would like to keep
running (in 32-bit mode) if possible, but I want to avoid having
a pot-pourri of libs of various ages and compatibilities.  Can
someone provide insight into whether the amd64 upgrade will
provide 32-bit comptible copies of all libs in the 4.0 installation?


Any advice appreciated . . .

Andrew.