Re: boot directory prefix in grub-install (even with --root-directory)

[Robert Millan]

On Tue, Dec 22, 2009 at 01:18:42PM +0100, Vladimir 'φ-coder/phcoder' Serbinenko 
wrote:
> Grégoire Sutre wrote:
> > Hi,
> >
> > grub-install copies GRUB images into ${rootdir}/boot/grub (where
> > ${rootdir} is empty by default and can be changed with --root-directory).
> >
> > To install GRUB files on a partition that contains a /boot file, one
> > must specify a non-empty --root-directory, and grub files are then
> > copied into /DIR/boot/grub.  Or one could mount the partition on a
> > mount point of the form DIR/boot and specify --root-directory=DIR to
> > force installation into the /grub directory of the partition.  Both
> > solutions are not completely satisfactory.  Is there a better one?
> >
> > The problem arises e.g. with NetBSD which uses /boot for its own
> > bootloader.  The script util/grub-install.in contains lines to take
> > care of that situation (lines 160-172), but these lines rely on a
> > variable ${host_os} that is not set.  This might be deprecated code
> > from GRUB Legacy's grub-install, where ${host_os} is set by a
> > configure substitution.
> >
> > An alternative solution would be to have grub-install install in
> > ${rootdir}/grub, with ${rootdir} equal to /boot by default.  The
> > default behavior (with no --root-directory) would be the same.
> The main problem is with scripts already using --root-directory and
> relying on existing behaviour. I propose add a new option
> --grub-directory=DIR
> which defaults to ROOTDIR/boot/grub
> What do you think about this?

If we do this, I'd just replace the old option completely.  But a standalone
--grub-directory is a bit more complex.

It seems to me that the current scheme is laid out this way because we didn't
have grub-mkrelpath / make_path_relative_to_its_root() when designing it.  A
proper solution would be to accept --grub-directory, then extract the relative
prefix from it.

-- 
Robert Millan

  "Be the change you want to see in the world" -- Gandhi