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Date:      Tue, 17 Dec 2002 06:20:16 +0100
From:      Cliff Sarginson <cls@raggedclown.net>
To:        freebsd-questions@FreeBSD.ORG
Subject:   Re: Dual booting FreeBSD 4.7 and Windows XP
Message-ID:  <20021217052015.GH81755@raggedclown.net>
In-Reply-To: <20021216214817.34c3e30e.judmarc@fastmail.fm>
References:  <016e01c2a553$7a2021f0$1a00a8c0@HOME> <200212170052.gBH0q3F18007@clunix.cl.msu.edu> <20021216214817.34c3e30e.judmarc@fastmail.fm>

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On Mon, Dec 16, 2002 at 09:48:17PM -0500, Jud wrote:
> On Mon, 16 Dec 2002 19:52:02 -0500 (EST)
> Jerry McAllister <jerrymc@clunix.cl.msu.edu> wrote:
> 
> [snip]
> > If it finds a bootable slice that it
> > doesn't recognize, it just calls it '???' (but still knows how to 
> > load its boot sector and pass off control.  For slices on disks that
> > don't look bootable, it just ignores these and doesn't even list them
> > in the menu.
> 
> Strictly speaking, the ??? isn't because the bootloader doesn't
> "recognize" the slice, but that the filesystem it does recognize on that
> slice has more than one name and might belong to one of several
> operating systems.  In the case of NT/W2K/XP, the filesystem is called
> NTFS by MS, HPFS by OS/2, and I believe QNX may use it as well.  Some
> sort of user-configurable name might be built in to the FreeBSD
> bootloader, but AIUI that would be difficult to do within its extremely
> small size.  Grub and other bootloaders do this by means of user config
> files and other pieces that live outside the bootloader itself, and so
> don't have the size limitation.
> 

Yes the point is that Grub does not really "know" how to boot anything
except Linux and Hurd (which is vapour-ware). In the menu for grub you
tell it what to do so to speak, it does not actually know anything about
the OS itself...ok, it has some idea about FreeBSD slices, it
understands the BSD notation for it. This is what makes it so flexible.
Since it was designed in the wan hope that all OS'es will become what I
think is called multi-os compliant (which they have not) it has these
hooks to load anything you tell it to.

As regards Windows, it is the same kind of entry you make whether it is
95, 98, Millenium or XP. I think there may be an issue with NT/2000 but
I don't know for certain. 

At the risk of being repetitious I will say, once you have got hold of
how it guesses the disk ordering in your system the rest is easy. This
it guesses from what the BIOS tells it, and in the case of it getting it
wrong (which I have never seen happen, and one of my network machines
has a relatively complex setup vis-a-vis booting) you can manually
adjust the mapping it makes between it's naming of disks and your
systems.

The system I am writing this mail on can boot FreeBSD 4.7, 5.0, 2
versions of Linux, Windows ME and Windows XP. It has 2 IDE disks and 2
SCSI disks. The boot setup is on one of the SCSI disks and is duplicated
on one of the IDE disks. This is where you *really* need to know how Grub does
it's disk numbering. 

Go for it. The initial pain is worth it.
You can always create (and should do so) bootable Grub floppies for the system
anyway.

The only thing I have not been able to get it to do is to boot off of
the second SCSI disk, but I think this is because it may not get enough
information from the BIOS on how to do so.

-- 
Regards
   Cliff Sarginson 
   The Netherlands

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