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6. The GRUB Bootloader

6.1. GRUB Basics

Fedora uses the GRUB bootloader. Short for GNU GRand Unified Bootloader. GRUB is a powerful and versatile bootloader that meets most needs. For other platforms such as IBM System Z or cloud images, Fedora may use other bootloaders, but because they are not likely to multiboot, this document does not address them.
The primary configuration file for GRUB describes the menu presented to the user, including the options passed to each operating system definition it boots. It also contains options for GRUB itself, such as the default option, timeout before continuing to the default option, and the visual presentation of the menu.
On BIOS systems, this file is located on the boot partition, as /boot/grub2/grub.cfg.
On UEFI systems, this file is located on the UEFI system partition, as /boot/efi/EFI/fedora/grub.cfg.

Do not edit GRUB configurations directly!

Any changes made directly to the GRUB configuration files will be overwritten when the file is regenerated, such as after a kernel update. Instead of editing these files directly, edit the templates that are used to generate them. This process is covered in Section 6.4, “Configuring the GRUB Bootloader”
GRUB can identify and directly boot most Unix type operating systems. You only need one GRUB configuration to boot them all, but each should have a dedicated /boot partition. Operating systems such as Windows cannot be booted directly, but GRUB can identify and chainload them.