[syslinux] Changes to get CD to boot on EFI System.

[Thomas Schmitt]

Hi,

Michael D. Setzer II wrote:
> Fedora 23 on the machine from DVD, and 
> that went fine, and it setup an EFI boot from grub.

That's the current state of the art:
EFI booting out of an ISO filesystem does not work with SYSLINUX.

All bootable ISOs i know use GRUB for EFI booting. Even the
option --uefi of program isohybrid is to be used with a GRUB2 equipped
FAT filesystem image that is already in the ISO as its second El Torito
boot image.
Matthew Garrett developed this ISOLINUX+GRUB2 layout for Fedora. Many
other distros follow his example.
The next popular alternative is the layout of grub-mkrescue which boots
both, BIOS and UEFI, by GRUB2 software.
And then there is SuSE which grafts a second ISO superblock and
directory tree onto an ISO which contains a GRUB2 boot image for EFI.
(Less popular only if we count SuSE as 1 user, not by its many human
 users.)

I proposed to mention this peculiarity in the isohybrid article of the
SYSLINUX wiki, but Ady, the only other person who commented on that
proposal, had objections.


Ady:

I understand that it is sub-optimal to deprecate the project's
EFI software in favor of the competition without even knowing
why exactly SYSLINUX EFI fails to boot out of an ISO 9660 filesystem.
But as we see, the question re-occurs after a few months.

How can we augment
  http://www.syslinux.org/wiki/index.php?title=ISOLINUX
  http://www.syslinux.org/wiki/index.php?title=Isohybrid
so that users do not believe to have missed the trick for UEFI booting
from optical media ?


Have a nice day :)

Thomas