grub error 22. Bad partition table? [solved]
debian at herakles.homelinux.org
Thu Nov 25 21:36:03 UTC 2004
On Friday 26 November 2004 04:23, John DeDourek wrote:
> Duncan Lithgow wrote:
> > I'd better mark this thread solved...
> >> That suggests to me that it's probably safest to put grub in hda1 or
> >> so, and mark that partition bootable.
> > That's the default isn't it? Paul said that MBR is in the first part of
> > hda1 - and because I'm also running windows it _has_ to be marked
> > bootable (or somewhere before 1024 has to)
> > Thanks again for the help
> > Duncan
> Just a clarification. There is a boot block at the beginning of
> disk (BEFORE the first partition) and a boot block at the beginning
> of every partition. "MBR" refers to the boot block at the beginning
> of the disk.
R==record. The first secor, 512 bytes.
The code I was inspecting fits into onse sector.
> Now, something that I'm less sure of. If you put grub into the MBR
> (means code in the MBR and the 1.5 stage in the following sectors)
> then it can boot any partition, marked "bootable" or not.
> If you install grub in some other partition (technically the boot
> block of that partition with stage 1.5 in the following sectors)
> then the code executed first will be whatever is installed in MBR.
> If that code is installed by windows, then I believe that it loads
> the code from the boot block of whichever partition is marked
> bootable. That would have to be the partition with grub in the
> boot block if you want to bring up grub.
The code in the MBR finds the first "bootable" partition. This is the coe
Windows installs to clobber Grub.
Back when I used to (sometimes) use Windows NT and (mostly) OS/2 Microsoft
documented how to make "the other OS bootable." One went into Disk Mmngler
and marked the other partition bootable.
Normally that other parition contained OS2/ Boot Manager.
> Now if you want that grub to chain load windows, I think (but am
> not sure) that you need to change which partition is bootable
> (using grub commands in grub.conf) to mark the windows partition
> bootable before you chain to its boot loader.
There was no mucking around needed with Boot Manager. Whether I booted OS/2,
NT or Linux with it, on the next reboot Boot Manager got started.
Installing Windows NT after OS/2 caused NT to boot in place of Boot Manager,
but that was easily overcome as I've already mentioned.
> Perhaps someone more knowledgeable about grub could confirm or
> correct this latter comment.
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