From owner-freebsd-questions@freebsd.org  Wed Aug 31 00:29:57 2016
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Date: Wed, 31 Aug 2016 02:29:51 +0200
From: Polytropon <freebsd@edvax.de>
To: Warren Block <wblock@wonkity.com>
Cc: Manish Jain <bourne.identity@hotmail.com>,
 "freebsd-questions@freebsd.org" <freebsd-questions@freebsd.org>
Subject: Re: Is it necessary to reinstall OS upon motherboard change?
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On Tue, 30 Aug 2016 17:16:50 -0600 (MDT), Warren Block wrote:
> On Tue, 30 Aug 2016, Manish Jain wrote:
> 
> > Because of certain problems I am experiencing with my hardware, I am
> > planning to move to another motherboard + CPU. Just out of curiosity, I
> > wished to enquire - is it possible to use an existing FreeBSD
> > installation despite change of MB + CPU ? In the Windows world, that is
> > pretty much impossible, but on FreeBSD the possibilities don't appear
> > that bad to me. (My hard disk and graphics card will remain unaltered).
> 
> Yes.  The two things that might require adjustment are network interface 
> names (re0 to em0, say) and disk device numbers (ada0 to ada4).  If you 
> use labels, the disk device numbers don't matter.
> 
> So the first boot might be to single user, remount / and other 
> partitions manually, then edit /etc/fstab and /etc/rc.conf.

Yes, those steps are quite often needed. Labels usually save you
from altering /etc/fstab, but device names of network cards or
installed optical drives might change, depending on the setup.
X without xorg.conf will usually work if the required driver
has been (pre)installed, otherwise xorg.conf often needs to
be adjusted. If you use "exotic" hardware, loading specific
kernel modules might be needed. In worst case, a rebuild of
a (custom) kernel might be useful - depending on the actual
requirements.

All those changes do not require a re-installation of the OS.


-- 
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...