Dual booting problems

[RW]

On Fri, 2 Mar 2007 11:37:26 -0500
Jerry McAllister <jerrymc at msu.edu> wrote:

> On Fri, Mar 02, 2007 at 12:34:10AM +0000, RW wrote:
> 
> > On Thu, 1 Mar 2007 13:30:26 -0900
> > Beech Rintoul <beech at alaskaparadise.com> wrote:
> > 
> > > I should also mention that you need the FreeBSD boot manager on
> > > both disks, or an alternative boot manager such as grub or gag.
> > > Read the handbook.
> > 
> > I recall reading that too, but I've never understood what it's
> > supposed to achieve. I imagine it must be a quirk of the FreeBSD
> > boot manager, I've certainly never needed to install more than one
> > copy of GAG or LILO. 
> 

> If you select F5 (maybe F6 or more,  I should try that some time) it
> will instead cause the MBR from that second (maybe third, etc) disk
> to be loaded and passes control to it.   Then that MBR looks at its
> own slice table and makes up a menu if there are more than one
> bootable slices on that drive.   

In other words it *is* a quirk of the FreeBSD boot manager, in that it
doesn't allow you to chainload a partition on another drive directly.
You have to chainload the intermediate MBR which needs a second copy of
the bootmanager. Most bootmanagers can do this directly, using the
partition table on the other drive.