I have only seen the block device allocation change when disks were added. I have never seen the block device allocation change on a single disk system. Regardless, using UUIDs is a much safer practice long term.

It also happens if you unplug the drives and put them back in a different order.
I did this once, OK, I was adding new drives for a RAID1 install, and forgot to record which socket each disk was plugged in to originally and got some what confused for a while. However even if you don't add drives just permuting the existing drives would do it.

fsmithred wrote:

	append initrd=/initrd.img ro root=/dev/sda1

It's better to identify the root partition with UUIDs, the block device allocation can change from one boot to the next.

	append initrd=/initrd.img ro root=UUID=$uuid

^ Replace $uuid with the actual UUID of the root partition.

Great point! However, I have only seen the block device allocation change when disks were added. I have never seen the block device allocation change on a single disk system. Regardless, using UUIDs is a much safer practice long term.

	append initrd=/initrd.img ro root=/dev/sda1

It's better to identify the root partition with UUIDs, the block device allocation can change from one boot to the next.

	append initrd=/initrd.img ro root=UUID=$uuid

^ Replace $uuid with the actual UUID of the root partition.

ui menu.c32

label devuan
        menu label devuan
        kernel /vmlinuz
        append initrd=/initrd.img ro root=/dev/sda1
        timeout 20

More  /boot/extlinux/extlinux.conf  options can found at

https://git.zytor.com/syslinux/syslinux … slinux.txt

https://wiki.archlinux.org/index.php/sy … tion_table

Then follow the instructions in the first post, except for the dd command.
Change the following

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

to this:

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

If you want to use UUID instead of device names in the menu, edit the 'append' line to replace

root=/dev/sda1

with something like

root=UUID=xxxxxxxxxxxxxxxxxxx

(replace xxxxx... with the correct uuid.)

You can easily switch from using grub as a bootloader to using extlinux (and back again if you want).

Run the following commands as root. Replace /dev/sda and /dev/sda1 with the correct drive and partition for your system.
BE SURE YOU NAME THE CORRECT DEVICES!

apt-get install extlinux syslinux-common
mkdir /boot/extlinux
extlinux --install /boot/extlinux
dd if=/usr/lib/EXTLINUX/mbr.bin of=/dev/sda bs=440 count=1
cp /usr/lib/syslinux/modules/bios/*.c32 /boot/extlinux

Create a boot menu with your favorite text editor, add the following lines and save it as /boot/extlinux/extlinux.conf

ui vesamenu.c32

label devuan
	menu label devuan
	kernel /vmlinuz
	append initrd=/initrd.img ro root=/dev/sda1

Reboot

If you want to add a splash image and 5-second timeout, copy a 640x480 png (or jpg) image named splash.png (or splash.jpg) to /boot/extlinux and add the following lines to extlinux.conf:

ui vesamenu.c32
menu background splash.png
timeout 50

label devuan
	menu label devuan
	kernel /vmlinuz
	append initrd=/initrd.img ro root=/dev/sda1

There are more things you can do with the menu. See syslinux documentation for more information:
http://www.syslinux.org/wiki/index.php?title=Menu

To revert to booting with grub, run

grub-install /dev/sda

Reboot

To switch back to extlinux again:

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

Reboot