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🔁 Migrate from UEFI to (Legacy) BIOS
Tuesday 28 February 2023 4 versions

Migrating Grub from a UEFI system to a BIOS (legacy) system 🔁

The general steps are:

- Boot the computer using a live boot image - Eg. System Rescue Image
- Mount the root filesystem1
- Bind mount `/dev`, `/sys`, `/proc` and `/run`2
- Change your EFI boot partition to `EF02 BIOS boot partition`3
- Chroot into the mounted file-system
- Re-install Grub 4

Here is someone who has documented this process in good detail:

#grub #seabios #coreboot #uefi

1. Mounting BTRFS subvolumes needs an extra option ↩︎

2. `for f in dev sys proc run; do mount --bind /$f /mnt/$f; done` ↩︎

3. Remember to use `gdisk` if you have a GPT partition table. The BIOS boot partition code is `EF02` ↩︎

4. `grub-install /dev/sda` ↩︎

# See Also

- 👢 Detect UEFI or BIOS Tuesday 28 February 2023