Booting several ISOs with GRUB2 on Fedora 34

[Patrick Frank]

Friendly greetings,

with GRUB2 I would like to boot several ISOs directly from harddisk.

My main drive with Fedora is a Kingston SA2000M8500G detected as
/dev/nvme0n1 but strangely displayed by GRUB2 as (hd1). The data drive
is a Seagate ST1000DM010-2EP102 detected as /dev/sda and displayed by
GRUB2 as (hd0). The ISO files are then located on (hd0.gpt1) in
"/iso/file_xy.iso".

Then I put in the file /etc/grub.d/40_custom the following code:

menuentry "Fedora 34 with XFCE" {
  insmod part_gpt
  insmod linux
  insmod search_fs_uuid search --no-floppy --set=partition --fs-uuid
3748ef02-5461-4c66-96a8-14fa03aad3f7
  set isofile="/iso/Fedora-Xfce-Live-x86_64-34-1.2.iso"
  export $isofile
  loopback loop ($isopart) $isofile
  linux (loop)/isolinux/vmlinuz root=live rd.live.image quiet
iso-scan/filename=$isofile
  initrd (loop)/isolinux/initrd.img
}

This leads to the GRUB2 errors "no server specified" and "load kernel
first". By trying some settings from various websites, my previous
mistakes which lead to the errors "unknown filesystem", "invalid
filename" and "out of memory" could have been resolved. But now I am
stuck. Most search results were dated from 2011 to 2014 and I assume the
syntax in GRUB2 changed since then. Either way, it would be great if
somebody could help me to get this working.


Regards,
Patrick