borked my grub boot config and can no longer boot my old kernel

[Jim Cornette]

Matt wrote:
> On Sat, 21 Feb 2004 10:45:40 -0500, Jim Cornette wrote:
>  <snip>
> 
>>You can also use the rescue disk and then select the fedora 1 
>>installation. If the boot sector is /dev/hda1 or /dev/hdb1 you can 
>>chainload the other installations from the installation on the /hda11 
>>and above installations.
>>
> 
>  <snip> 
> 
>>To get grub to boot from a chainloader with the /dev/hda1 installation, 
>>I had to boot into the installation that had the boot mount as /dev/hda1 
>>and run grub-install /dev/hda1 for that installation. I booted into the 
>>installation that had /dev/hdb1 as the boot partition and ran 
>>grub-install /dev/hdb1.
> 
>  <snip>
> 
>>The benifit with this method is that each installation has it's own boot 
>>partition and when updated it updates its independent grub.conf file.
> 
> Jim, this method interested me although I'm not totally sure I understand
> it. :o) What exactly does grub-install do? And how do the two grub.conf's
> work together? I currently chainload Windows 98 but I wasn't aware you
> could chainload a second linux grub boot loader.
> 

The way that I understand it is that grub starts loading from wherever 
you designate it to start. If the partition is marked active, the BIOS 
should be able to boot grub from it.

If you install grub on /dev/hda1 and /dev/hda1 is active, you should not 
need grub in the MBR and it will boot. I assume that it would boot from 
any primary partition that is marked as active. (hda1 - hda4)

I have only used the first partition to boot grub from, unless installed 
  in the mbr for drived in and extended partition.


What happens with multiple boot partitions and multiple areas of grub 
installs is that one installation only sees grub for it's intended boot 
partition. If you add or delete the kernel on one installation, the 
change does not mess up another instance of the OSes grub file.

Using chain loading, from one grub installation to the other saves a lot 
of manual editing when installing a new kernel. Everything is more 
automated.

About how grub-install actually works. I am not sure. I do know that it 
works when installed on primary partitions and chainloaded.

JIm