Make it work with dracut-based/Fedora-type ISOs

[probonopd]

Fedora-type ISOs (using dracut rather than casper) can now be ISO-loop-booted too:

http://git.kernel.org/cgit/boot/dracut/dracut.git/commit/?id=aef0f557910d73bf9a6b2a1bdf670135e4c4d152

It would be great if grml-rescueboot would pick up these automatically, too.

Since documentation is hard to find, this is a GRUB entry that works for me:

linux (loop)/isolinux/vmlinuz0 root=UUID=4935-13FB iso-scan/filename="/boot/grml/Fedora-19-Nightly-20130430.09-i686-Live-desktop-20130430.09-1.iso" rootflags=loop liveimg rootfstype=auto selinux=0 quiet rhgb

[bam80]

@probonopd wasn't initrd needed from (loop)?

[bam80]

To make it work for Fedora and probably others UEFI-boot ISOs, I came up with the following snippet:

set iso=/home/bam/Downloads/Fedora-Silverblue-ostree-x86_64-31-1.9.iso
search --file --no-floppy --set $iso
loopback loop $iso
configfile (loop)/EFI/BOOT/grub.cfg