+1edbarx wrote:I found EFI booting is much simpler than legacy boot.
The non-UEFI version of GRUB needs a special BIOS boot partition to hold the bootloader because there is no space for it on a GUID partition table.edbarx wrote:I couldn't make legacy boot work on a GPT formatted disk.
https://en.wikipedia.org/wiki/BIOS_boot_partition
I like to use gdisk to generate the BIOS boot partition: press "n" to add a new partition and accept the default start and end sectors (these will be 34 & 2047, respectively, in a full disk) then select partition type ef02 and use "w" to write the changes to the disk — *do not* format the new partition.
Once this is done, the non-UEFI version of GRUB can be installed and used.
https://packages.debian.org/jessie/grub-pc
However, some motherboards will not boot with this method at all and it is recommend to use a traditional "MBR-style" (msdos) partition table instead on disks to be used in a non-UEFI system.
@OP: disable Secure Boot.