Recently I setup my work laptop to dual boot Arch Linux and Ubuntu server with syslinux as my bootloader. I setup the laptop with a dedicated /boot partition that would be shared between the two operating systems. I added this boot entry to /boot/syslinux/syslinux.cfg
.
LABEL ubuntu
MENU LABEL Ubuntu
LINUX ../vmlinuz-3.8.0-29-generic
APPEND root=LABEL=UBUNTU rw
INITRD ../initrd.img-3.8.0-29-generic