Add / Enable "32Bit UEFI Support" in Ubuntu?

[lorn10]

Hi there!

I want to add here a request regarding the addition of a very nice, currently Fedora-exclusive, feature. It's called "32Bit UEFI Support" and makes it possible to boot and install a 64bit Linux onto a 32 bit (U)EFI based system which contains a 64bit CPU.

Source: https://fedoraproject.org/wiki/Changes/32BitUefiSupport

So far I understand, this works through a special modified BOOTIA32.EFI file. That one acts as some kind of a "wrapper" which converts some (essential) EFI64 calls to EFI32 (during the boot-up).

I have tested this principle with latest Fedora 31 at an early Intel iMac which contains a 64bit CPU but has a 32bit EFI. To my big surprise it works absolutely GREAT!

There exist currently some ways to apply this principle also at other Linux Distros like Ubuntu and Debian. Unfortunately these are all quite complex and needs a lot of modifications. More information can be found at the following link:

https://medium.com/@realzedgoat/a-sorta-beginners-guide-to-installing-ubuntu-linux-on-32-bit-uefi-machines-d39b1d1961ec

I tried to modify a Kubuntu 18.04 LTS DVD ISO image but I failed. Fedora Linux uses a quite different DVD install layout (folder & file organization) which is not easy applicable at Ubuntu / Debian based Distros. In detail I tried to copy the mentioned BOOTIA32.EFI wrapper file into the /EFI/boot directory. Well, the edited / modified Kubuntu DVD image was not recognized by the 32bit EFI firmware (at an iMac). I have uploaded some of the needed files. Fedora seems to include also a special macboot.img file which is not present (in that form) in Ubuntu.

Update 18.12.2020:
The following link shows a step-by-step guide how an installation can be done with latest Ubuntu / Kubuntu 20.04 LTS: https://wiki.ubuntuusers.de/Howto/32-Bit_EFI/

As mentioned in my initial request the main problem lies in the missing grubia32.efi file. That one is unfortunately not included at current Ubuntu 64 bit x86-64 install medias. So it is needed to add it from another Distro like Debian 10.

Note, Debian supports that "64bit CPU & 32bit EFI" install option since Version 8: https://wiki.debian.org/UEFI#Support_for_mixed-mode_systems:_64-bit_system_with_32-bit_UEFI

Kind regards

C. Leu

[Mario Limonciello (superm1)]

This isn't really a feature request in efibootmgr as much as it would be for GRUB.

[lorn10 (kle)]

I have now added a little update to my original feature request post. It points to an how-to which shows how Kubuntu 20.04 LTS can be installed in an mixed-mode UEFI system.

It should be also noted that Debian supports this that "64bit CPU & 32bit EFI" install option since Version 8. For me it is somewhat a mystery why Ubuntu doesn't also offer it...

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Julian Andres Klode (juliank)]

It's a cute little feature, but I think the decision was made long ago that the resources needed to maintain it outweigh the benefit of supporting a handful of old Macs and Bay Trail devices.

I want to note that we *do* ship unsigned 32-bit grub, so in theory, if you want to hack this together it should be as easy as installing grub-efi-ia32 after booting and installing in BIOS mode.