memdisk:/usr/lib/syslinux/memdisk:https://packages.debian.org/stretch/syslinux-common
sbootmgr:http://ftp.lanet.lv/ftp/mirror/Slackware/isolinux/sbootmgr/
title Boot "CDDVD" kernel /boot/grub/memdisk initrd /boot/grub/sbootmgr.dsk
OSインストール後、BIOSメニューが起動しないマシンで[Removale]はエラーとなったが、[Quit to BIOS]でDVD読んだのでOK
http://d.hatena.ne.jp/gunshot/20081109/p1
https://cutecomputer.wordpress.com/2006/10/10/boot-cdrom-through-grub/
https://askubuntu.com/questions/311568/boot-from-cd-drive-in-grub2
GRUB2 itself doesn't have support to boot from CD, but it supports booting
from ISO files. You could copy the ISO of the CD you want to boot from, to
the hard drive and then create a custom grub entry
http://ubuntuforums.org/showthread.php?t=1549847.
めも、未検証
