Re: [gentoo-user] Installing Gentoo: Grub, alternate GNU/Linux system on another partition

[Alan McKinnon <alan.mckinnon@gmail.com>]

On Mon, 5 Dec 2011 12:23:28 -0800
"Alan E. Davis" <lngndvs@gmail.com> wrote:

> I'm giving Gentoo another try, having been using Ubuntu for quite a
> while, and more recently Mint.  I would like to be able to access
> Mint until the Gentoo system is working as I'd like it.
> 
> I have gotten through the install, for the most part, up to grub.  I
> can see how to edit the grub.conf file for my Gentoo partition.
> However, it isn't clear to me from the examples how to write a
> grub.conf entry for Mint's root (/) partition, on /dev/sda8. I am
> asking for advice on writing the grub.conf file.
> 
>  Here are the various partitions involved:
> 
>     Gentoo:
>        /boot      /dev/sda1
>        /            /dev/sda2
> 
>    Mint    (/boot is not separate)
>        /           /dev/sda8
> 
> The Mint kernel is using an initramfs, while I have manually
> configured the kernel on Gentoo, at least for now.
> 
> Grub 2 is not transparent to me.  The kernel is:
> 
>     /boot/vmlinuz-3.0.0-13-generic
> 
> the initrd-img file is:
> 
>    /boot/initrd.img-3.0.0-13-generic
> 
> My grub.conf file for gentoo would look like this:
> 
> ###########
> default 0
> timeout 30
> #splashimage=(hd0,0)/boot/grub/splash.xpm.gz
> 
> 
> title Gentoo Original
> root (hd0,0)
> kernel /boot/kernel-3.0.6-gentoo-r1 root=/dev/sda2
> ###########
> 
> 
> I have a few other questions of a more or less minor nature.  Perhaps
> better to ask them separately.
> 
> Alan Davis

Dual boot scenarios get tricky, it is vital to assume nothing. You left
out a lot of info, so I have to make some reasonable assumptions. Reply
with corrections if we're going to wrong route.

You can only have one primary bootloader, either grub from Gentoo or
grub2 from Mint, it cannot be both. But it looks like that's what you
do have. Seeing as you intend to drop Mint eventually, you must
uninstall grub2 and all it's files from Mint.

Your supplied grub.conf will only work if you have a boot -> . symlink
present on /dev/sda1. Gentoo normally does this for you.

For Mint you probably need something like this:

title Mint
root (hd0,7)
kernel /vmlinuz-<whatever_mint_uses> root=/dev/sda8 ro quiet splash
    <any_other_mint_params
initrd  /initrd-<whatever_mint_uses>


You can pick up the correct kernel and initrd arguments
from /boot/grub/grub.cfg on /dev/sda8 by looking in the menuentry
sections.


-- 
Alan McKinnnon
alan.mckinnon@gmail.com