[syslinux] Getting classic BIOS and UEFI boot on the same disk?

Ady Ady ady-sf at hotmail.com
Wed Aug 21 09:04:42 PDT 2019

> We're using the classic boot BIOS syslinux successfully for many years,
> but meanwhile it's getting harder to buy hardware the still supports
> this boot mode. The option for us would be syslinux EFI boot. To avoid
> too many changes we would like to generate an image for our different
> hardware parts that supports both - classic BIOS boot and (U)EFI boot.
> This would allow us to leave the BIOS in whatever state it is and the
> system will simply boot.
> I read some articles on how to install each version - from that I would
> carefully say that this is not possible... At least not when following
> the install instructions. The biggest gap seems to be the MBR and the
> GPT...
> Might there be a way to handle this actually? Or do both modes
> completely exclude each other? I won't mind duplicating some files that
> are required for each boot process but could not be placed in the same
> location...
> And - if there is already a howto for this topic - blame me, I didn't
> find it :-)
To me, it is not so clear what exactly is your goal.

Do you want to build an image for an internal HDD that could be capable 
of booting in both, BIOS mode and UEFI mode?

Or, is this for a portable (USB) device?

Or, is this for some kind of ISO image?

Or, is this for some kind of network-booting, in order to install OSes 
to the internal HDD?

Additionally, what OS(es) are you planning to boot from Syslinux (in 
either BIOS mode and/or UEFI mode)?

Is the resulting image expected to support multiple OSes? Which ones 
(e.g. Windows, Linux)?

Depending on the answers to these questions, the answers to your 
original questions (might) vary.


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