[REGRESSION] Re: [PATCH v4 5/5] efi: Use generic EFI loader for x86_64 and i386

[Jan Čermák]

Hi Ard, everyone,

On 23. 05. 23 17:31, Ard Biesheuvel wrote:
> Switch the x86 based EFI platform builds to the generic EFI loader,
> ...

We use GRUB as the loader for the Home Assistant Operating System (based 
on Buildroot, using mostly unpatched GRUB 2 build [1]) and after 
updating to the latest 2.12 release, this patch (commit 
cfbfae1aef0694b416aa199291cfef7596cdfc20) has been identified to break 
boot on Intel Atom NM10, at least with upstream kernel 6.6 with 
CONFIG_EFI_STUB enabled. I reproduced it on Intel D525MW board, and 
there are some more reports from HAOS users on Github [2].

Initially, we decided to revert the patch [3] for the time being, 
however, while it fixed issue for users running on those rather old 
boards, it broke boot [4] on the comparatively newer Fujitsu Esprimo 
Q920. From the user reports, there is no BIOS update available that will 
make any difference but reverting to a "vanilla" 2.12 fixes that.

Do you have a clue what could have gone wrong, either with the original 
patch, or why the revert breaks the other platform? I'll be happy to get 
any details and perform tests on the NM10 board I have here. 
Alternatively, I can also ask users with the Q920 for more details or do 
some tests.

Regards,
Jan

[1] 
https://github.com/home-assistant/buildroot/tree/2024.02.x-haos/boot/grub2
[2] https://github.com/home-assistant/operating-system/issues/3305
[3] https://github.com/home-assistant/operating-system/pull/3324
[4] https://github.com/home-assistant/operating-system/issues/3348