Repairing a failed grub_pc installation

[Toomas Tamm]

Hello all!

I had configured the grub_pc installation incorrectly on a particular
host and the computer failed to boot after installation. I thought it
would be easy to repair when I re-boot the machine into sysinfo and use
the console (or remote ssh) to chroot into the target system and
re-configure grub2.

To my surprise, I did not succeed.

First, the sysinfo system had not mounted /usr, /var, etc under /target.
Wasn't it the case some years ago that a system booted into FAI sysinfo
automagically found the root partitition and used the /etc/fstab there
to mount the remaining partitions under /target ? Has this functionality
been lost somehow?

Once I manually had mounted /usr, I was met by an
incomplete /target/dev. While the "global" /dev contains 176 entries,
including /dev/sda, /dev/sda1, etc, the one at /target/dev has only 94
entries, and is, in particular, missing the disk entries /dev/sda,
/dev/sda1, etc. After some trial and error, I succeeded in creating
these manually. Why were they missing?

Even at this point, the command
# $ROOTCMD grub-install --no-floppy --modules="lvm raid" '(hd0,2)'
failed with
error: no such partition
error: no such partition
error: no such partition
error: no such partition
grub-probe: error: Cannot find a GRUB drive for /dev/sda7.  Check your
device.map.

(and more of the same)

Here I wonder why it is looking at the /dev/sda7, which was the
original, erroneous partition I was trying to install grub_pc into
during the original automatic install.

And why is it still failing to correct the error?

Any insight into all these problems? I think I shall just re-install the
computer with proper GRUB_PC configuration at this point, but I am still
curious why the /target and /target/dev were incomplete in the repair
system?

I am using FAI 4.0~beta2+experimental45 .

Toomas Tamm