Question about "EFI mixed-mode support" in MX Linux [Solved]

[lorn10]

A new topic. How it looks about the "EFI mixed-mode support" in MX Linux? Is the kernel built with the corresponding "EFI mixed-mode" flag? (https://wiki.gentoo.org/wiki/EFI_stub)

This is of course relevant only for the x86-64 build of MX Linux. However, that feature would be very useful for quite some later Intel Atom based systems which were 64 bit capable but had an 32 bit UEFI firmware.

More information can be found in the topic here: https://github.com/systemd/systemd/issues/17056

Note, theoretically this should work also on early x86 Apple EFI based systems. But because those were made (long) before the UEFI handover specification was finalized it doesn't. So it looks that Apple's own EFI spec does something different. While Apple never supported it officially in Mac OS X, the macosxbootloader project has shown that it works (https://github.com/Piker-Alpha/macosxbootloader).

[dolphin_oracle]

if you are asking if MX will boot on 32 uefi firmware, the answer is yes. and has for a long time.

[lorn10]

Okay, but I mean not the usual way through the CSM "legacy BIOS emulation" mode (which is present on most older UEFI firmware).

I talk here about the native booting in UEFI mode but between different EFI "bitnesses". As far I remember that EFI "mixed-mode" capability was introduce in Linux kernel 5.7. Therefore it is not that old.

So if I take my old iMac as an example I can boot MX Linux only with the 32 bit build in native EFI mode. The 64 bit version has to be installed via the CSM "legacy BIOS emulation" mode. With the help of the EFI mixed-mode capability it would be possible to install also the 64 bit MX Linux variant in native EFI mode. (If Apple would follow more the UEFI specification.)

Whatever, as mentioned, it is confirmed that this works fine for Atom based Netbooks.

[fehlix]

I talk here about the native booting in UEFI mode but between different EFI "bitnesses". As far I remember that EFI "mixed-mode" capability was introduce in Linux kernel 5.7. Therefore it is not that old.

Maybe this helps:

Debian Jessie (8.0, released on April 2015) was the first Linux distribution to include full support for mixed-mode UEFI...

[lorn10]

Yeah, and most likely the other sentence "As of 2023 and Debian 12 the amd64 installation media (available in netinst form) includes the UEFI boot loaders necessary for both i386 and amd64 boot." indicates that this was enabled also in the kernel.

Whatever, so you are adapting simply the behavior of Debian. Now I'm wondering if that's true also for Ubuntu.

In any case, this did not work when GRUB was involved. But it should work with recently released GRUB 2.12 (which now finally support also the EFISTUB / Linux kernel booting from EFI capability).

[fehlix]

In any case, this did not work when GRUB was involved. But it should work with recently released GRUB 2.12.

Maybe provide details of your attempt to make it work with current GRUB,
within a new thread and a more specific thread title, so it may be easier to find by other
users who may have similar issues.
Thanks