Here is a more complete but quick summary of my points and of my story,
after more reading and thinking.
Unless I'm asked for information, this will probably be my last message.
First, something I forgot to say, Debian Installer is a marvelous
program, kudos !!!
I mean it much (that's why I write all this).
- Debian installer requests that other systems boot by PBR (chain
loading) but does not do it itself by default.
- It presents PBR boot as a valid option, but grub-install calls it a
VERY BAD idea (Richmond's idea?)
- Richmond's OS bootloader seems a good idea: it perfectly works since
the 1980s and is never heard of but Grub makes an abundant user
literature, mostly about problems.
- A self contained PBR OS bootloader as simple as Richmond's is the
essence of my suggestion, in particular to allow easy recovery, in
addition to whatever other possible booting one may use.
- It may use simpler software than Grub but Grub is OK if it works and
if it's invisible (not to fiddle with).
- In particular, it should not require to contain the UUID of its own
partition. Using UUID=0 or some other magic number to indicate
"myself", also valuable in /etc/fstab, is a suggestion I made in an
Ubuntu bug, but it has been closed repeatedly.
- The installation DVD should contain a menu entry to repair the
booters. Presently, I found a help.ubuntu article instructing to boot
the Desktop liveDVD and either to install/run (needing Internet) a
package that is not found or to run grub-install which is certainly not
for the average user and did not work in a Virtualbox Virtual Machine.
- Using an extra, intermediate partition (the, as Windows usually leaves
one) is indeed a good solution because everyone agrees with it. In fact,
it's what I was using on my previous computer with Grub1. But it should
be done by the installer, not by the user, of course. Why I did not
continue that way is because Grub2 complicates things. I don't know it
and I don't want to learn it (more than Richmond's), there are many
other more useful and pleasing things to learn.
- as a side note, I'm using no swap partition but swapspace (Richmond's
too). I have a feeling that putting the swapspace in the middle of the
data means less disk seeks. The installer might propose to install it as
an alternative to the swap partition.
My story, Debian should make an everybody's story more simple:
- installed GAG and copied working PBR-booting partition from old
system. It displays "GRUB " and stalls.
- installed Ubuntu 12.04 that destroyed GAG
- reinstalled GAG and U 12.04 with PBR bootloader
- 12.04's Grub would boot 10.04, had to upgrade GRUB1 and grub-install
to have it boot directly.
- configured VirtualBox to run GAG + 10.04 in a virtually mapped real
partition.
- created more U 12.04 partitions with PBR boot
- this was a complete mixup: all partitions except 10.04 were presenting
the same Grub menu and the labeling of the partitions was confusing. The
only way to understand was my own partition-what index but two labels
referred to sda7 (one instead of sda8).
- I finally gave up and installed Grub on MBR.
- my main system was, of course, in the middle of the menu but I guessed
that reinstalling grub from it would put it on top and it did. Speaking
of mixup, I noticed that most recent GRUB2's labels no longer indicate
neither partition number nor OS version.
- after that, I noticed that the 10.04 partition no longer boots in
VirtualBox ("GRUB " again): it looks like MBR GRUB2 destroyed it.
- that remains on my very long todo list.
(1) a partition may boot by MBR on the real disk and by PBR on a mapped
partition on Virtualbox.
Thanks again
