Re: Advise on how to debug screen with only GRUB and blinking cursor and possibly save my dualboot installation

[Sophoklis Goumas]

On Mon, 19 Dec 2022 at 10:30, Pascal Hambourg <pascal@plouf.fr.eu.org> wrote:
>
> "GRUB" alone means that the GRUB boot image was loaded but could not
> load the GRUB core image (it would have printed "loading" after "GRUB").
>

This kind of confirms the output of the boot-repair-disk which I've only used
for debugging the situation, namely:

>
> Grub2 (v1.99-2.00) is installed in the MBR of /dev/sda and looks
> at sector 2048 of the same hard drive for core.img, but core.img
> can not be found at this location.
>

I haven't used any of that disk's/utility's "repair" options so that
the system will not get messed up any further and I'd like to retain it's
current status for the reason I explain further down.

>
> This is wrong. A BIOS boot partition (bios_grub flag) should not contain
> a filesystem. The purpose of this type of partition is exclusively to
> store a raw GRUB core image.
>

This setup, as unconventional/wrong as it is, WAS working flawlessly
for more than 4-5 years and I'd like to retain its status as it is, so that
by everyone's guidance, I might get to the culprit of this mess up.

I would like to take the chance, also to express my thanks to those
who so patiently help me debug this over @ #grub on the Libera IRC
Network.

So what I am requesting, is some command template (dd or not) that
will allow me to either extract/verify the partition table type (GPT/MSDOS)
or its structure.

>
> In the rest of the data it appears that /dev/sda1 (hd0,gpt1) is used as
> /boot. Running grub-install installed the core image in the first 103
> sectors of /dev/sda1 and probably ruined the ext4 filesystem beyond repair.
>
> If /dev/sda1 can be repaired and mounted without data loss:
> - Reduce sda1 by 1MB and change its type to "Linux filesystem".
> - Create a new 1 MB BIOS boot partition in the free space.
> - Reinstall GRUB
>
> If /dev/sda1 cannot be repaired and mounted any more:
> - Reduce sda1 to 1MB.
> - Create a new ext4 partition in the free space.
> - Mount the new partition as /boot. Update /etc/fstab.
> - Reinstall the kernel images and initramfs and GRUB
>

Thank you for providing me with a suggested recovery procedure. I think
I will simply do a fresh new re-installation taking the chance to probably
move to a more robust system setup as I will most probably not be able
to physically be around my hardware and I would most certainly benefit
from any type of upgrade to its setup.

However, I might retain this disk for the sake of further examining it and
to be able to get to the real reason why a system that was working got
messed up by the Windows Automated Repair and to where exactly this
stopped the system from being able to boot despite its unconventional
setup, even though these type of systems (NON (U)EFI) are no longer
the case.

Sophoklis