Recently, I migrated a computer from a 2TB hard disk to a 4TB hard disk, which means I had to switch from DOS partition layout to GPT. However, this PC was not booting with UEFI. On another PC I am booting with UEFI. Which means, I am managing different bootloader scenarios, all with Syslinux. In this post I want to collect my notes to keep an overview over my setups.

I am usually using Arch Linux, which means that in some scenarios syslinux-install_update can be used. Arch Linux also has a Wiki page on Syslinux.

GPT partition table with UEFI

Let’s start with the probably most common scenario nowadays, UEFI with a GPT partition table.

For UEFI you need an EFI System partition, this is a partition type that you can set with fdisk or other partitioning programs. Syslinux needs to be copied into a folder EFI/syslinux on this disk (to be honest, I am not sure if it really must be in a EFI folder or if this is only convention).

If you have mounted your EFI System partition at /boot you can use the following commands:

mkdir -p /boot/EFI/syslinux
cp -r /usr/lib/syslinux/efi64/* /boot/EFI/syslinux

Then, you can register the boot loader on UEFI with (assuming /dev/sdXY here):

efibootmgr --create --disk /dev/sdX --part Y --loader /EFI/syslinux/syslinux.efi --label "Syslinux" --verbose

From here on, you can configure /boot/EFI/syslinux/syslinux.cfg as usual.

According to the Gentoo wiki the latest added entry gets highest priority, thus on the next boot Syslinux should be automatically started.

Note: Gentoo also specifies that backslashes instead of forward slashes must be used for --loader, but the Arch Wiki uses forward slashes. According to the output of efibootmgr -v on my PC they get automatically converted to backslashes.

GPT partition table with BIOS

Let’s assume you have a GPT partition table, but are still using standard BIOS booting.

For this, you need to set a legacy boot flag on the boot partition in your GPT partition table. This can be done with parted:

> print  # to list partitions and their numbers
> set 1 legacy_boot on  # to set legacy_boot on partition number 1

Again, I am assuming that you mounted your partition to /boot. We can now copy all Syslinux files over to the partition.

mkdir /boot/syslinux
cp /usr/lib/syslinux/bios/*.c32 /boot/syslinux/

Then, we install Syslinux:

extlinux --install /boot/syslinux

And finally, we need to install the gptmbr.bin boot loader (assuming /dev/sdX is your disk containing the boot partition):

dd bs=440 count=1 conv=notrunc if=/usr/lib/syslinux/bios/gptmbr.bin of=/dev/sdX

DOS partition table with UEFI

Not sure if I am running this anywhere, but it seems to be the same installation as GPT with UEFI.

DOS partition table with BIOS

In this mode, we can use syslinux-install_update from Arch. For this, /boot must be mounted. Then, execute:

syslinux-install_update -i -a -m