This is a three step procedure:
- Use
gdisk
to convert the partition type from MBR to GPT (without data loss). - Use
gdisk
to add a new BIOS boot partition (EF02
type). - Use
grub-install
to install the boot loader into the new BIOS boot partition.
Before starting, make sure you have a backup, and make sure to have a linux live boot ready to rescue your system. It's easy to mess this up!
gdisk /dev/sda
n
to create a new partition. Needs to be about 1MB. You can probably squeeze this in from sectors 34-2047. UseL
orl
to look up the code for "BIOS boot" (ef02).
w
partprobe /dev/sda