Bug#502446: debian-installer: grub-installer is not updated for grub-pc introduction

[Osamu Aoki <osamu@debian.org>]

Hi,

Thanks for interesting comment.

On Sun, Nov 16, 2008 at 12:40:12PM +0100, Robert Millan wrote:
> On Sun, Nov 16, 2008 at 07:36:52PM +0900, Osamu Aoki wrote:
> > 
> > I wonder why we offer to install grub-pc to non-MBR locations in lenny.
> > For me, disabling that is an option. But fixing it is even nicer. 
> 
> Erm, we shouldn't be doing this.  When installing in a partition head, you
> can't really check if there will be enough space.  It depends on how much is
> reserved by your filesystem of choice, which is often not enough anyway.
> 
> And even if it is, it's an ugly hack to reuse a partition for two different
> things at the same time.

Hmmm...  interesting thought.  If this is true, I agree we should drop
asking non MBR location.

But many Linux distros allow us to install boot loader in chain-loading
mode at MBR or head of partition of ext2/3 as I remember.  

I thought for modern HDD with LBA, there is always first track = 63
sectors = 31.5KiB available in MBR and partition head (formatted with
ext2/ext3/vfat/... at least) which grub assumes to use for GRUB Stage
1.5.  (I know there were days when I envyed HDD with 10 MB capacity and
only 17 sector per track.   Then grub should have problem istalling it
to it.)
 
> > > This is something we already solved in GRUB 2 (by using UUIDs).
> > 
> > I wonder if GRUB2's /etc/grub.d/30_os-prober can be used from
> > grub-installer in squeeze.
> 
> Should be no problem.  It just takes installing os-prober in the target
> system before update-grub is run.

I thought so too and tried it.  But as I tried update-grub command in
chroot at /target while having os-prober installed in chroot from
installer, it did not find other partitions.  /chroot/dev directory did
not have /chroot/dev/sda etc.   /dev/sda etc. were there but could not
be seen from chroot.

> > I guess chroot does not have appropriate
> > devices to get this script to produce right result.
> 
> I don't think so.  If devices were missing, grub-probe / grub-setup wouldn't
> work in this environment, and installation wouldn't be possible.

Device was not missing.  /dev/sda exists.  But issuing chroot /target
without appropriate care in advance caused problem.  Thus there is need
to write code :-)  

Osamu