Re: [gentoo-dev] grub:2 keywords

[Mike Gilbert]

On Fri, Jun 29, 2012 at 2:38 PM, Rich Freeman <rich0@g.o> wrote:
> On Fri, Jun 29, 2012 at 2:29 PM, Mike Gilbert <floppym@g.o> wrote:
>> It does copy all of the images to /boot so that the grub shell can be
>> used to install an MBR image. grub:2 no longer has an interactive
>> shell and grub2-install must be used. Therefore, copying files to
>> /boot in the ebuild is completely pointless.
>
> Does grub2-install place any stage files where they need to be, or are
> they no longer needed?  I haven't experimented with it yet.
>
> Normally grub1 needs to be able to find the stage2 file, and that has
> to be on a partition the stage1.5 can read (I believe stage1.5 is in
> the diagnostic cylinder - it only uses the files in /boot during
> installation).

grub2 eliminates the stage_1_5 files. Instead, a "core" image is built
by grub2-install.

Here's how it works.

1. grub2-install copies all grub modules to /boot/grub2. This can be
any file system readable by GRUB.
2. grub2-install calls grub2-mkimage which combines any modules
necessary to access /boot into core.img.
3. grub2-install calls grub2-bios-setup which installs boot.img into
the MBR and embeds core.img into the sectors immediately after the
MBR.

>
> I'm not sure if grub2 completely eliminates the need to have a
> "normal" partition somewhere, in a situation where raid+lvm+etc are
> used.

You do need a filesystem that grub2 can access through some
combination of modules, and an area in which to embed core.img.

The grub2 manual has a pretty good explanation.

http://www.gnu.org/software/grub/manual/html_node/Installing-GRUB-using-grub_002dinstall.html
http://www.gnu.org/software/grub/manual/html_node/BIOS-installation.html
http://www.gnu.org/software/grub/manual/html_node/Images.html