Re: Accessing boot menu when GRUB_TIMEOUT=0

[Andrei Borzenkov]

On Wed, Jan 18, 2023 at 1:03 PM AAA BBB <thebudget72@gmail.com> wrote:
>
> Dear Andrei,
>
> thank you so much for your suggestions.
>
> I got it working by setting `GRUB_TIMEOUT_STYLE=hidden`.
>
> I confirm that SHIFT alone doesn't work, but SHIFT+F1 pressed before
> booting up the system indeed shows the GRUB menu.
>
> May I ask if you have more details on why SHIFT alone doesn't work?
>

Initially EFI interface to read console input did not even offer any
way to query SHIFT state. Reading the current UEFI specification, it
seems to allow it, but still it is not clear whether we can query the
modifier state without reading any character (what exactly is returned
in this case). It sounds like we can, but then it needs additional
support in grub code.

> Is there another button that would work alone?
>

Current grub should check for F4 as interrupt character so it may work.