[lug] Multi OS booting

Lee Woodworth blug-mail at duboulder.com
Sun Nov 20 15:03:19 MST 2005


D. Stimits wrote:
> William Petty wrote:
> 
>> I have a system with multiple SCSI drives with a different OS on each 
>> drive.
>> In the past, I just copied the MBR from the Linux drive (Using DD) to
>> C:\BootSec.lin and added it to the windows boot manager.  This always
>> worked for LILO, but it fails using grub. When given the choice of OS's,
>> and I select Linux, all I get is the word "GRUB" on the screen and 
>> nothing
>> else happens unless I reset.
You need to do a grub install, just copying the MBR doesn't work.
You may find it useful to lookup what these commands could do for you:
grub> root (hdx,y) -- this is the partition with the grub files
grub> setup (hdx) -- this is the boot disk
NOTE: there are 2 parts to installing grub:
1) getting the files onto a filesystem (root fs or a separate boot partition)
2) installing an MBR that knows where the stage 1.5 parts are installed
    in the fs. I am pretty shure the installed MBR uses sector-level
    addressing to locate the stage 1.5 parts. This means that if you
    move those files in the fs, you need to reinstall the MBR.
> 
> 
> Grub always points at an ext2 partition. You could point a windows boot
All of my partitions are XFS, even the boot partition. You just need to
have the right stage 1.5 parts referenced by the MBR.

> loader at a grub MBR, but the grub MBR would then load the ext2. The 
> trick I would think is that you must install a grub MBR that points at 
> the right partition with the disk order and bios setup that is correct 
> when windows boots. If you do anything to change your disk order, you're 
After grub gets past the stage 1.5 load, it reads file systems and looks
for its config file (menu.lst or grub.conf).
> probably going to fail. I don't know if booting windows has any effect 
> on the bios drive number, if it does you might have to adjust grub to 
> think of drives in the same order that windows does. I've had other bios 
> drive number problems mixing scsi and ide which I never solved, 
> primarily because there seems to be no way to point grub specifically at 
> the other drive type chain such as ide versus scsi...it only understands 
> the bios number. It seems that whichever drive chain is chosen in bios 
> as the boot drive will cause the other to lose any bios drive number.
> 
>> I have looked at going the reverse direction, and adding windows to the
>> grub menu, but I do not want to revert to the old hiding/unhiding 
>> partitions
Lookup the grub chain directive for booting win type oses.
>> game. (AKA OS-2) Besides, I want the other volumes mounted while
>> running Linux.
> 
> 
> I'm probably going to try the hiding game, but I'm really nervous. If I 
> were to boot up windows just one time when windows thinks I'm booting d: 
> instead of c: it'll entirely hose the registry, unrevocably.
> 
> Maybe someone on list can tell me, is grub's hide feature capable of 
> hiding entire drives, or just partitions? I have things arranged such 
> that if pop out a removeable bay drive, it boots windows, otherwise it 
> boots linux. If I leave the linux drive in, the windows drive would 
> think it is d: (fatal to windows). So before I'm willing to attempt it, 
> I have to know if grub can make windows think that d: is now c:.
> 
>> My controller will boot the lowest SCSI ID first, but in the case of 
>> an IDE
>> disk being present, then the motherboard forces the IDE to precede all of
>> the SCSI devices with no option of reversing the order.   I.E. I would 
>> like
>> Windows to be on an IDE drive, thus the boot preference.
> 
> 
> I've never found any solution to this.
> 
>> P.S.  I have also tried using all SCSI drives.
> 
> 
> So far as I know this is the only solution.
> 
> D. Stimits, stimits AT comcast DOT net
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