Re: How can we identify an ISO file is an EFI bootable ISO image?

[Laszlo Ersek <lersek@redhat.com>]

On 06/20/17 19:36, Rod Smith wrote:
> On 06/20/2017 12:47 PM, Laszlo Ersek wrote:

>> For UEFI boot, only the ElTorito image matters.
> 
> MOSTLY, yes; however, some EFI implementations include ISO-9660 drivers.
> This is definitely true of the EFI used by VirtualBox. I think I've seen
> this feature on one or two UEFI-based PCs, too, but I don't recall the
> details and I can't say I'm 100% certain of this. There are also
> ISO-9660 drivers floating around that can be loaded from a FAT
> partition. In either of these cases, the files on the ISO-9660
> filesystem can be used to boot from an optical disc, even if it lacks
> the El Torito image.

Good point!

> This is admittedly a corner case at best; but IMHO it's worth keeping in
> mind, since non-matching El Torito and ISO-9660 files could lead to user
> (or developer) confusion.

That has actually tripped up at least one OVMF user in the past; they
had some inconsistency between the two locations. The problem was
originally reported in  <https://github.com/tianocore/edk2/issues/93>
("OvmfPkg: UEFI Shell only sees EFI\BOOT\BOOTX64.EFI"), but now that the
edk2 github issue tracker is gone, the ticket cannot be viewed even in
read-only mode. :/

Thanks!
Laszlo