Well, I’ve been trying to boot Fedora from ISO, but haven’t exactly been successful. On the bug, you can see a possible fix, but it’s a bit complicated and requires messing with the image from an existing install.

Instead, I figured out a way to do it that uses the extracted files. It’s pretty simple. First, mount the ISO and extract three files:

  1. the LiveOS image: squashfs.img and possibly osmin.img,
  2. the compressed kernel: vmlinuz0, and;
  3. the initial ramdisk initrd0.img

In case you were wondering, the copies in the EFI and isolinux directories are the same. You can then place all these files in a subdirectory on the drive. Then you add an entry to GRUB pointing to the files. In this case, I placed the files in /boot/F12-$arch and the drive’s label is LiveLinux.

menuentry "Fedora 12 32bit" {
    linux /boot/F12-i686/vmlinuz0 root=live:LABEL=LiveLinux \
        live_dir=boot/F12-i686 rootfstype=auto ro liveimg quiet rhgb
    initrd /boot/F12-i686/initrd0.img