Re: Dual boot question

On Sat, 07 Jan 2006 00:03:41 +0100, Peter T. Breuer <ptb@xxxxxxxxxxxxxxx> wrote:

Alan Adams <alan.adams@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
[snip]
> I have a bootable grub floppy. I don't understand how to use it. 

Read about it using the command "info grub".

Basicly, you can boot your system using the floppy, without relying on any
mbr setup, or you can do the setup of the mbr.

Boot like this:

(insert the floppy and boot. You get a prompt "Grub> ")

  Grub> find /boot/grub/grub.conf
  (hd0,6)

This tells you have a partition in disk 0, seventh partition (numbering
starts at 0) that contain a file named /boot/grub/grub.conf.  Now that
you know what partition to boot from, issue this command:

  root (hd0,6)

and then

  cat /boot/grub/menu.lst

This allows you to see the name of the kernel file, and the kernel
command line options. Now you can simply copy the commands as you  see
them in the file (finish off with the command "boot"), or even simpler,

  configfile /boot/grub/menu.lst

will give you the standard menu, as configured in the config file.  Just
use the arrow keys to highlight the stanza you want, and hit enter.

If you don't have a working config file, you can directly issue the
commands that you would have put in the config file.  If you don't
remember the details of the linux kernel's file name, use "tab
completion":

  root (hd0,6)
  kernel /boot/<TAB>

You will see a list of files in /boot.  You get no help from Grub to fill
in any kernel command line options. You usually need "root=/dev/hda7".

  initrd /boot/...
  boot

The second thing you can do with the boot floppy is to "setup" the mbr.
You need to start as above, to make sure which is the partition that
contains the grub files and the kernel(s).

  root (hd0,6)
  setup (hd0)

The last command without a comma and partition, just the disk.  If you
actually want to have the dos/windows mbr there, you can specify a
partition, to have grub place the boot sector there. (Notice that the
first partition starts usually in sector 63, so the MBR does not belong
to any partition.)  After booting into linux, you use "dd" to extract
512 bytes from the start of the partition, and into a file.  Copy this
file somehow to the Windows partition, and name it in the boot.ini.
That will let you chainload grub after first starting ntloader.

[snip] 
  * Creating a GRUB boot floppy::
  * Installing GRUB natively::
  * Installing GRUB using grub-install::

Let's try number two. Well, willya lookit thet. Just what I said: 

Native, that is what you do when *not* running grub under linux.
Grub must be started directly from the bios, using the grub floppy or
after grub has been setup, by escaping out of the grub boot menu.

  grub> setup (hd0)


Now you try. 

You need the "root (hd0,6)" command first, to tell where the grub
files and the kernels are.

You can do the setup while running linux. Then you are adviced to use
"grub-install".  Just "grub-install /dev/hda".  There are a few scenarios
where grub-install gets it wrong, if there are multiple disks, and an
unexpected one has been set up in the bios to be the boot drive.
This does not seem to be the case here, so this command should work.

-Enrique
.

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