On 18/12/2022 at 20:49, Sophoklis Goumas wrote:
I got to seeing simply a black screen only display GRUB and a blinking cursor as is also shown here: https://i.stack.imgur.com/4zJNc.jpg
"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").
My system is non-(U)EFI and it has two operating systems each on "its own" disk, namely: a debian GNU/Linux installation on a GPT partitioned disk (/dev/sda) and a Windows 10 on a installation on a MBR (MSDOS) disk (/dev/sdb).
# parted /dev/sda print Model: ATA WDC WD1003FZEX-0 (scsi) Disk /dev/sda: 1000GB Sector size (logical/physical): 512B/4096B Partition Table: gpt Disk Flags: Number Start End Size File system Name Flags 1 1049kB 2149MB 2147MB ext4 bios_grub 2 2149MB 19.3GB 17.2GB linux-swap(v1) swap 3 19.3GB 1000GB 981GB lvm
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.
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
