Add guide for EFI iso creation to https://wiki.debian.org/DebianInstaller/Preseed/EditIso

[Christoph Terasa <terasa@kohlio.de>]

Hi,

I recently decided to create a preseeded ISO for Debian deployment at 
our lab, and created the final ISO according to the guide at 
https://wiki.debian.org/DebianInstaller/Preseed/EditIso. I was able to 
boot the ISO in legacy mode on a VirtualBox VM, and from a thumbdrive on 
real hardware as well. Sadly the guide does not mention how to re-build 
the ISO so that it can be booted in EFI mode.

I pieced together commands for xorriso from various internet sources. I 
added the options

    -eltorito-alt-boot --efi-boot boot/grub/efi.img \
    -append_partition 2 0xef boot/grub/efi.img \

to the xorriso command. The resulting ISO is bootable in both the 
VirtualBox VM and the real hardware. Is this the preferred/correct way 
to create an EFI-bootable ISO?


kind regards,
Christoph