This information might help:
http://www.syslinux.org/wiki/index.php?title=Isohybrid

On Fri, Nov 10, 2017 at 8:28 PM, Andy Stewart <kb1oiq@mval.net> wrote:

Hi everybody,

I've noticed that the Ubuntu 16.04 ISO is bootable on systems with BIOS
as well as UEFI.  From scratch, I've remastered Ubuntu, but my ISO file
is only bootable via BIOS.  I'd like to remedy that situation by
figuring out what magic is needed so that my ISO file can be booted
either way.

I have a chroot directory in which my files live.  I have scripts that
convert all of that into an ISO file.  My guess is that I need a
new/modified incantation of mkisofs plus some additional files for UEFI.

Despite a lot of searching, I've not yet found the info that I need.

If you have definitive information, please let me know.

Thanks!

Andy

--
Andy Stewart (KB1OIQ)
Founder:   Worcester Linux Users' Group
Founder:   Chelmsford Linux Meetup Group
President: PART of Westford, MA (WB1GOF)
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