Remove GRUB and install extlinux:

apt purge grub-pc grub-common grub-pc-bin grub2-common && rm -rf /boot/grub/ && apt install extlinux syslinux-common

If /boot is not on separate partition:

extlinux --install /boot

Otherwise:

extlinux --install /boot/extlinux

Overwrite GRUBs master boot record:

dd if=/usr/lib/syslinux/mbr/mbr.bin of=/dev/sda bs=440 count=1

For boot menu copy:

cp /usr/lib/syslinux/modules/bios/menu.c32 / # text menu

OR

cp /usr/lib/syslinux/modules/bios/vesamenu.c32 / # graphical menu

cp /usr/lib/syslinux/modules/bios/lib* /

Create /extlinux.conf in / . Example conf:

default linuxAAA
label linuxAAA
   kernel vmlinuz
   append initrd=initrd.img root=/dev/sda1 ro quiet

label stari kernel
   kernel vmlinuz.old
   append initrd=initrd.img.old root=/dev/sda1 ro quiet

timeout 60

ui vesamenu.c32

If stuck in boot> menu prompt use:

vmlinuz initrd=initrd.img root=/dev/sda1

to boot images linked in / directory on /dev/sda1.

• https://github.com/SolarNetwork/solarnetwork/wiki/Node-OS-Setup-Guide-Debian-8#use-extlinux-in-place-of-grub-bootloader
• http://www.syslinux.org/wiki/index.php?title=SYSLINUX#TIMEOUT_timeout