I'm dual booting Ubuntu 12.04 with Arch. I'm using Ubuntu's GRUB to pull in other OS's. Because Arch switched to systemd, all I had to do is add an option in the linux line of the /boot/grub/grub.cfg. The addition is:
How do you edit grub.cfg to add this option?
Do/Can I edit /etc/grub.d/30_os-prober because that's where Arch entry section in grub.cfg is located?
Do I use the /etc/grub.d/40_custom file and fill in the entry? OR..
Use the GRUB_CMDLINE_LINUX= at /etc/default/grub?