Comment 2 for bug 1900185

I do not care about the loopback.cfg file itself, but about this particular kernel parameter: "iso-scan/filename=$iso_path".

It can also be added in the grub.cfg file (see Manjaro Linux):

if [ -n "${iso_path}" ]; then
  isoboot="iso-scan/filename=$iso_path"
fi

menuentry "Ubuntu" {
 set gfxpayload=keep
 linux /casper/vmlinuz file=/cdrom/preseed/ubuntu.seed maybe-ubiquity $isoboot quiet splash ---
 initrd /casper/initrd
}

This allows you to save many different distributions and system versions on one USB stick and makes it easy to update them later.

Example: writing an ISO image on 16 GB and bigger USB does not make sense, it is not practical.

Additionally, we can enable exfat support in the kernel, which makes it much easier to use larger ISO files (over 4 GB).

Practical examples of using "isoboot": https://github.com/Mexit/MultiOS-USB