[Glastonbury] dual boot issues

[Kelvin McNulty]

I dual boot SuSE 8.1 and it uses Grub but the Windows is 98 SE on one machine 
and ME on the other. I have heard about XP doing weird stuff... but if you 
ever get into that situation with the earlier versions you can recover it by 
reinstating the boot sector on the boot hard disc (c: in windows). When I 
first installed SuSE, for a while I was using floppy boot to go to Linux and 
hard disc boot to go to Windows until I figured it out.

From the SuSE 7.2 Reference Manual (was the first version of SuSE that I 
installed):

",,,DOS must be installed on the first hard disc. The executable code in the 
MBR (Master Boot Record) ("first stage boot loader") tests whether the marked 
partition contains a valid boot sector..."

so the DOS boot code must always be there. So yes, Windows is fussy about 
having to boot from the beginning of the disc.

For a while I kept a binary image of the Windows version of that sector, the 
first 512 bytes of which 446 contain the boot loader, and a binary image of 
the Linux dual boot loader, so I could swap between the two... but now that I 
have three computers all working I have relaxed enough to not need that 
anymore...

There is a process you can do in Windows 98 SE to restore the boot sector to 
an MS-DOS one but I don't know if that will work with XP, but it ought to.

I recall using another Windows machine to make a floppy on which I could run 
an MS-DOS command (having booted from the floppy) to restore the Windows boot 
sector on the hard disc...

Ah - here is how to do it (from the SuSE 7.2 reference manual):

in Windows 98, once you have rescue-booted into it, get a MS-DOS prompt

C:\> 

 and type: FDISK /MBR

This writes the 446 byte bootloader into the MBR.

You can use the dd command to copy a file out of or into the MBR in Linux:

WARNING - DO NOT USE THIS UNLESS YOU UNDERSTAND IT
and take care not to switch if and of or you might lose everything by making 
it do the operation the wrong way round....
Read the man pages for dd in Linux. ( man dd at a shell prompt).

dd if=/dev/yyyy of=mbrbackup bs=512 count=1
The above makes a backup copy of the MBR

and

dd if=mbrbackup of=/dev/yyyy will write the backup boot sector back into the 
MBR.

where yyyy is the name of the disc you are booting from e.g. hda1, hda2 etc.

I did use those commands for a while to switch into and out of being windows 
bootable and I offer them in the knowledge that IF YOU MISUSE THEM YOU MIGHT 
END UP WITH AN UNBOOTABLE COMPUTER - like if you write the MBR in the wrong 
place you might wipe the partitioning so you can't get at your data even with 
a rescue disk. YOU HAVE BEEN WARNED - try the above at your own risk.

I disclaim all responsibility... etc. and offer the above with happy memories 
of how empowering it felt to do the above and get out of the clutches of 
Micro$oft once and for all.

But with Windows XP, when googling about it, I do remember seeing things about 
XP boxing clever, so you'll need to look that up... don't use XP on any of my 
computers and don't think I ever want to...

Best,

Kelvin

On Tuesday 11 May 2004 23:16, tim hall wrote:
> Peter,
>
> On Tuesday 11 May 2004 20:59, peter.t.cole wrote:
> > OH dear it installed linux ok but would not boot into windows he coul
> > not recover windows the only way he could restore windows was to pull
> > the hard rive an install in another machine and do a secure erase ( he
> > did use partition magic to create the partition for Linux).
>
> Were you using lilo or grub? (i.e. how were you trying to boot windows).
> It's kind of hard to answer your questions without knowing what the
> problems are in more detail. Are you _sure_ you correctly configured your
> bootloader?
>
> I know Windows is fussy about having to boot from the beginning of the
> disk, is this still the case? (I don't know as I don't double boot With
> windows). Forgive me if you've been using *nix since I was in junior school
> and this is something much more arcane.
>
> cheers
>
> tim hall
>
>
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