[syslinux] isohybrid has 2 variants

[Ady]

> Hi,
> 
> Ady:
> > -eltorito-boot EFI/BOOT/BOOTX64.EFI 
> 
> This is most probably wrong, as this seems to be the prescribed
> name for a file inside the EFI-understandable filesystem.
> This filesystem would not be the ISO 9660 but rather the FAT
> image file which serves as EFI boot image.
> 
> 
> > -eltorito-boot EFI/BOOT/BOOTX64.IMG 
> 
> This might be better. From where did you learn that name ?
 
This is just "the same" as the other one,
 "-eltorito-boot isolinux/efiboot.img"

but with a path that is more appropriate for "all efi stuff is 
located in the same directory tree" ways.
 
> 
> I still did not find information about how to create the FAT image.
> My best guess for now is to simply install enough SYSLINUX in a
> FAT filesystem image, so that it can chainload isolinux.bin from
> the ISO filesystem.
>   https://wiki.archlinux.org/index.php/Syslinux#Installation_2
> 
> But that's just a speculation. Maybe somebody should peek into
> Fedora Live CD: 
> 
>   # mount -o loop Fedora-Live-Desktop-x86_64-20-1.iso /mnt/iso
>   # mount -o loop /mnt/iso/isolinux/efiboot.img /mnt/fat
>   $ find /mnt/fat/efi/boot 
>   /mnt/fat/efi/boot
>   /mnt/fat/efi/boot/fonts
>   /mnt/fat/efi/boot/fonts/unicode.pf2
>   /mnt/fat/efi/boot/grub.cfg
>   /mnt/fat/efi/boot/bootx64.efi
>   /mnt/fat/efi/boot/grubx64.efi
> 
> Hrmpf. Obviously not SYSLINUX equipment in there.
> 
> Anybody can shed light on that issue ?
 
Unfortunately, at this time you won't find any ISO image that can 
boot by means of SYSLINUX.EFI from optical media; only with 
grub2-efi.

You could find an ISO image that can be extracted and "installed" to 
a USB drive (not with ISO9660) and then this USB drive can boot using 
SYSLINUX.EFI, although they are either using an "old" version of 
Syslinux 6.xx, or are in some "beta" stage.

The FAT image is used by grub2-efi, and has certain restrictions 
(e.g. alignment). Even some very popular posts / articles about this 
matter are incomplete.

In theory, an ISO image with (some versions of) UDF could also be 
used to boot in UEFI mode.
 
> 
> 
> Have a nice day :)
> 
> Thomas
> 
 
Regards,
Ady.