dual booting fc6, f8

[John Summerfield]

Gene Heskett wrote:

> So I guess I don't understand how grub works as well as I thought.  The info 
> pages might tell me, but it seems the only way to read them is backwards as 
> once you've gone down a tree to read something, there seems to be only one 
> way to back up, using the backspace key, but you never get back to the main 
> menu so its easier to 'q'uit it and restart it, but that screws with ones 
> train of thought till not even 2 more cups of coffee makes it make sense.
> 
> The other ugly thought is that my bios doesn't see the sata drive (sdc) at 
> all, and the couple of times I made it boot to f8, I had to move all the boot 
> files to /dev/hda1, but specify /dev/VolGroup01/LogVol00 in the kernel 
> argument line, but that seems to have quit working too.
> 
> What is the usual scenario here?
> 
> Should I do an hd assignment swap and then chainload to the sata drive?  But, 
> if the bios can't see it, I'd have to assume grub cannot either at that stage 
> of the boot.
> 
> Or should I just resign myself to having to maintain a boot partition on an 
> pata drive just so the system can even find its bootstrap files?  The 
> achilles heel there is that its only a 99 meg partition.
> 
> That would allow me to use that 200 megs for a dos partition, but what good is 
> that if the bios can't find it...  Sigh.
> 
> My thanks to all that have read this far.
> 

When you install a new kernel, and this applies to rpm-based systems and 
to deb-based system, _something_ automatically updates the grub's 
menu.lst (the "correct" name for the file containing the menu) for you.

the details differ between vendors, but it can only work if the system 
you're running on can see where is kernels are, and importantly, where 
the menu is.

My and large, this makes use of a single menu for all Linuxes (and maybe 
  other *xes) impractical.

What I do is create a menu for each, each as if it's the only OS on the 
computer.

Here is a fragment from an actual system i have that's configured to 
boot from two drives:

title Scientific Linux SL (2.6.18-8.1.15.el5xen)
         root (hd0,0)
         kernel /xen.gz-2.6.18-8.1.15.el5
         module /vmlinuz-2.6.18-8.1.15.el5xen ro 
root=/dev/VolGroup00/LogVol00
         module /initrd-2.6.18-8.1.15.el5xen.img
         savedefault
title Other
         rootnoverify (hd1,0)
         chainloader +1
         savedefault
[root at numbat ~]#

The "other" stanza boots the boot record from the _first partition_ on 
the second disk. More usual is booting the MBR:

title Other
         rootnoverify (hd1)
         chainloader +1

the result is that you can switch between different bootloaders on 
different drives. It worked for a drive on which I installed two RHEL5 
betas, SLES10 and opensuse10, it worked years ago when I had Darwin 
installed (before Macintels), and I would expect it to work for every 
disk the BIOS can see.

Normally I'd link to every bootable system from every bootable system.

For more details
pinfo grub

-- 

Cheers
John

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