When to set Boot flag and Legacy BIOS Bootable flag - Reddit When BIOS Bootable flag must be set: - You run on BIOS firmware (not UEFI) and use GPT table scheme (not MBR) Where Boot flag and BIOS Bootable flag must be set: - On partition where is saved bootloader
boot - Do you need to set bootable Flag when Installing Linux . . . The boot esp flags are normally on the ESP - efi system partition with UEFI and gpt partitioning Grub does not use boot flag, Windows in BIOS mode requires boot flag on its Boot partition or main partition if it has the boot files
set (Parted User’s Manual) Some or all of these flags will be available, depending on what disk label you are using: ‘bios_grub’ (GPT) - Enable this to record that the selected partition is a GRUB BIOS partition ‘legacy_boot’ (GPT) - this flag is used to tell special purpose software that the GPT partition may be bootable ‘bls_boot’
GParted, Partition, and Filesystem Flags - Linux. org If I understood everything correctly, you can boot a UEFI installed OS from an MBR grub, if you add a flag "bios_grub" to the UEFI partition and then add that entry to grub Arch Linux, Cinnamon; Core i7-12700F; RTX 3070 Ti 8GB, 64GB DDR5-4800, Corsair RM850e
configure grub to work with either UEFI or PC BIOS boot When using the parted utility, the "flag" for the ESP is boot, the "flag" for the BIOS Boot Partition is bios_grub, and the "flag" for boot is legacy_boot (I don't think GRUB cares about that legacy_boot flag, so I think it neither helps nor hurts my desired goal)
boot - Different types of file systems for the booting . . . Windows ties these partition table types to the boot method: MBR works only with the Basic Input Output System (BIOS) and GPT works only with the newer Extensible Firmware Interface (EFI) or Unified EFI (UEFI)