How-to boot Fedora ISO from HD with GRUB v. 2

[secipolla]

Now that we're approaching the release of Fedora 17, a convenient way to test the live-CDs is to boot them directly from the HD.
For that, its initrd image must be patched and it can be done easily with the script at https://gist.github.com/2132076
It's usage is on its headers. But for the latest KDE ISO I tried, there was a change that had to be made. I don't know if it was particular to that ISO or if all F17 ISOs now are like that.
Where we read "boot" in the script must be changed to "BOOT" (e.g., /EFI/boot → /EFI/BOOT).

So let's say we downloaded fedora.iso to /dev/sda3 (adapt the instructions to the actual ISO name or rename it).
We put the script in the same directory and patch the ISO's initrd:

./fedora-fromiso fedora.iso initrd-fromiso

Now we need to have a GRUB2 entry for it.
We can, for instance, create /etc/grub.d/35_fromiso with

#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
menuentry "Fedora Live" {
	loopback loop (hd0,3)/fedora.iso
	linux (loop)/EFI/BOOT/vmlinuz0 root=live:/fedora.iso rootfstype=auto ro liveimg quiet rhgb rd.luks=0 rd.md=0
	initrd (hd0,3)/initrd-fromiso
}

Note that I have (hd0,3) because the ISO is on /dev/sda3 but I don't put it after "root=live:" (but you need to change "fedora.iso" to its actual name, if it's the case).
Then make it executable, run '# grub2-mkconfig -o /boot/grub2/grub.cfg' and that should be it.

[secipolla]

In the F17-beta Xfce spin it's being used /EFI/boot again (not /EFI/BOOT) so that's what should be used in the script and the grub entry file.

[secipolla]

Now for F17 Xfce final we must use /isolinux/ instead of /EFI/boot/.
So we replace that in the script and also in the grub entry.
Suppose we rename the iso to simply 'fedora.iso' and put it in sda3/ISO/ together with the created initrd-fromiso. Then the grub entry (/etc/grub.d/35_fromiso; don't forget to make it executable) would be:

#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
menuentry "Fedora Live" {
	loopback loop (hd0,3)/ISO/fedora.iso
	linux (loop)/isolinux/vmlinuz0 root=live:/ISO/fedora.iso rootfstype=auto ro liveimg quiet rhgb rd.luks=0 rd.md=0
	initrd (hd0,3)/ISO/initrd-fromiso
}

[redtux]

just a point in the script I had to change all instances of30dmsquash-liveiso-genrules.sh to
30-dmsquash-liveiso-genrules.sh

[secipolla]

And did you manage to boot an F18 live-CD? Because I never did.
At least the GRUB menu entry that works with F17 doesn't work with F18.
It fails with 'can't find root=live:/ISO/...' or the like.

[Valent]

I have finally found a script that actually works booting Fedora 18 iso from usb:
http://git.marmotte.net/git/glim/plain/fedora18-fromiso

Details are here:
http://git.marmotte.net/git/glim/plain/README

Cheers,
Valent.