MBR to GPT

Q: How to convert from legacy MBR to GPT required for UEFI?

A: Follow ServerFault: How do I convert my linux disk from MBR to GPT with UEFI

Creating the “BIOS boot partition” is only needed if you want to do the conversion in small steps, e.g. convert to GPT first and still use grub-pc for booting. You can skip this step if you convert to GPT and grub-efi-amd64-bin at the same time.

Some more notes:

# Install software
apt-get install gdisk dosfstools grub-efi-amd64-bin efibootmgr

# Create EFI System Partition at end of disk
gdisk /dev/sda
# n
# <free>
# -1G
# <default>
# EF00
# w

# Format EFI partition
mkfs -t vfat -v /dev/disk/by-partlabel/EFI

# Mount EFI partition
raw="$(readlink /dev/disk/by-partlabel/EFI\\x20system\\x20partition)"
uuid="$(find /dev/disk/by-uuid -lname "${raw}" -printf '%f\n')"
install -m 0700 -d /boot/efi
echo "UUID=${uuid}	/boot/efi	vfat	umask=0077	0	2" >>/etc/fstab
mount /boot/efi

# Install EFI GRUB
grub-install /dev/sda --target=x86_64-efi --efi-directory=/boot/efi/ --bootloader-id=debian
efibootmgr -v
# efibootmgr -B -b X

reboot
# <F12> -> boot-mager -> local file -> EFI\debian\shimx64.efi

# Remove legacy GRUB
apt-get purge grub-pc grub-pc-bin
rm -rf /boot/grub/i386-pc

Written on March 10, 2022