Re: Need help installing Grub2

[Jordan Uggla]

On Sun, May 11, 2014 at 2:50 PM, Ronald F. Guilmette
<address@hidden> wrote:
>
>
> I have the following situation:
>
> I have a fresh brand new drive that I have partitioned (MBR style) using
> the Gparted Live CD.  I have also used the Gparted Live CD to copy a
> number of pre-existing partitions from other drives onto the new drive.
> In particular, I have copied onto the new drive:
>
>      1)  A Windows 7 recovery partition
>      2)  A Windows 7 boot/system partition
>      3)  A FreeBSD boot/system partition
>      4)  A FreeBSD data partition
>
> All space on the new drive is now occupied by the above partitions, except
> for the first 1 MiB of the drive.
>
> I have heard that Grub2 is a Good Thing[tm] and would like to install it
> and use it as a (multi-)boot manager on the above drive.  What is the
> simplest, fastest, and easiest way to accomplish this?
>
> I am a total n00b with respect to Grub/Grub2, so detailed instructions
> would be greatly appreciated.
>
> Must I first find a whole 'nother drive, install some flavor of Linux on
> that other drive, boot that other drive, and then use Linux to install
> Grub2?

Definitely not needed.

>
>
> Regards,
> rfg
>
>
> P.S.  I did make some modest effort to research this question before posting,
> and I even downloaded and burned the latest Ubuntu (desktop) onto a DVD,
> booted that into "live" mode, and then tried:
>
>         sudo grub-install /dev/sda
>
> but I only got an error saying something about "/cow".

Every grub-install command has an implied argument
"--boot-directory=/boot/" unless you specify --boot-directory
explicitly. What that means is that "grub-install /dev/sda" is
equivalent to "grub-install --boot-directory=/boot/ /dev/sda". So
you're telling grub-install to copy all its files to "/boot/", then
create a boot sector and core.img that will be able to read those
files. Except on a LiveDVD system "/boot/" is a read only filesystem
(DVDs and squashfs filesystems are read only), with a Copy On Write (
http://en.wikipedia.org/wiki/Copy-on-write ) overlay on top of RAM to
make it seem like you can actually write to it. The COW in /cow/
stands for Copy On Write, but all you really need to understand from
all of this is that since you don't want to use the DVD's /boot/,
because that simply doesn't make sense. You do however need a /boot/,
so you'll need to decide which partition should contain grub's
/boot/grub/, mount that partition somewhere, and pass the path to the
/boot/ directory on this partition to grub-install's --boot-directory
option and create an appropriate grub.cfg in.

http://www.gnu.org/software/grub/manual/html_node/Multi_002dboot-manual-config.html

-- 
Jordan Uggla (Jordan_U on irc.freenode.net)