Using grub2 we can directly boot an (iso9660) ISO using its loopback option. It provides another nice rescue method – for example when using grml (the Debian based Linux Live-CD for sysadmins. We no longer need to extract kernel and initrd from the ISO to be able to boot it using the isofrom bootoption. So we need to do is put a plain grml ISO to our harddisk.
If we are using grub2 already consider adding an entry like the following to our grub config

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