https://github.com/nricciardi/fix-grub
Fix GRUB after Windows update
https://github.com/nricciardi/fix-grub
Last synced: 3 months ago
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Fix GRUB after Windows update
- Host: GitHub
- URL: https://github.com/nricciardi/fix-grub
- Owner: nricciardi
- Created: 2024-12-09T18:31:38.000Z (6 months ago)
- Default Branch: main
- Last Pushed: 2024-12-09T18:45:38.000Z (6 months ago)
- Last Synced: 2025-02-09T05:39:01.968Z (4 months ago)
- Size: 3.91 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# Fix GRUB
Fix GRUB after Windows update.
## Prelimary checks
1. **Disable secure boot**, some systems can prevent GRUB execution if secure boot is enabled!
2. Sort correctly your EFI table in BIOS
## Fix GRUB using live system
1. Flash a live system (`.iso` file) into a USB/CD with a similar kernel of your broken system (e.g. same distro live ISO)
2. Mount your broken system on live system following your distro documentation
3. Re-install GRUB
### Mount broken system
Following commands are tried on _OpenSUSE Tumbleweed_.
Note your partitions devices, in particular your _root_ and _efi_ partions:
```bash
fdisk -l
```
You could see something like this:
```
/dev/nvme0n1p1 2048 534527 532480 260M EFI System
/dev/nvme0n1p2 534528 567295 32768 16M Microsoft reserved
/dev/nvme0n1p3 567296 522397695 521830400 248.8G Microsoft basic data
/dev/nvme0n1p4 1998360576 2000408575 2048000 1000M Windows recovery environment
/dev/nvme0n1p5 522397696 942319615 419921920 200.2G Linux filesystem
/dev/nvme0n1p6 942319616 1917495295 975175680 465G Linux filesystem
/dev/nvme0n1p7 1918881792 1998360575 79478784 37.9G Linux swap
/dev/nvme0n1p8 1917495296 1918881791 1386496 677M Microsoft basic data
```
I have 4 partitions:
- `/dev/nvme0n1p1` EFI partition (we must install GRUB here!)
- `/dev/nvme0n1p5 ` _root_ filesystem (we must bind this!)
- `/dev/nvme0n1p6` _home_
- `/dev/nvme0n1p7` _swap_
Mount broken filesystem:
```bash
mount /dev/nvme0n1p5 /mnt # mount root
mount -t proc none /mnt/proc
mount --rbind /dev /mnt/dev
mount --rbind /sys /mnt/sys
```
Switch to it using `chroot`:
```bash
chroot /mnt /bin/bash
```
Mount the remaining partitions:
```bash
mount -a
```
### Re-install GRUB
```bash
grub2-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=openSUSE
grub2-mkconfig -o /boot/grub2/grub.cfg
reboot
```
## Post fix
Reset Windows entry point in EFI:
```bash
grub2-mkconfig -o /boot/grub2/grub.cfg
```