openSUSE grub2 boot cd image iso of bios update

Add custom entry to /etc/grub.d/40_custom file:

#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
menuentry "Bios upgrade" {
    insmod part_gpt
    insmod ext2
    set root=(hd0,gpt2)
    linux16 /boot/memdisk iso
    initrd16 /boot/biosupgrade.iso
}


for gpt partition table root disk and root partition is second.
/boot/memdisk is copy of /usr/share/syslinux/memdisk part of syslinux package.

Then create new boot record:

$ sudo grub2-mkconfig -o /boot/grub2/grub.cfg


Reboot now and choose new grub2 entry Bios upgrade.