Dualboot with FBSD boot manager

Gary W. Swearingen garys at opusnet.com
Mon Aug 29 15:36:00 GMT 2005

Erik Norgaard <norgaard at locolomo.org> writes:

> Thanks, I tried to look at the options in the BIOS. I can enable or disable the SATA disks.

Look where you can tell it to boot off a CDROM and ensure that it can't
also be configured to boot off second hard disk.

> So, it appears that I have to install the FreeBSD bootmanager (or some other multiboot boot manager) on the XP disk?

On the boot disk, at least.  And depending on which BM you use, maybe
also on the other disk.  (Unless you want to have your BM on a floppy

> It's been more than 5 years since I had a multiboot, so I'd like to know how I can do this and still get back to the
> original settings. How can I backup the existing MBR?

>From a "rescue" floppy or some Unixy OS, use something like this:

     dd if=/dev/ad0 of=ad0.mbr count=1

Know that fancy BMs (not FreeBSD's; I don't know about XP's) partially
reside in other places than the MBR.  IIRC, Grub uses a few sectors
between the MBR and the first primary partition, plus some files in
a regular filesystem.

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