Comment # 38 on bug 1122614 from Michael Chang

(In reply to Guillaume GARDET from comment #37)
> (In reply to Michael Chang from comment #36)
> > Hi Guillaume,
> > 
> > Could you please check if you seen the message "Please press 't' to show the
> > boot menu on this console" and pressing the "t" could bring the menu or not ?
> 
> No, the last message on serial is: 
>   Welcome to GRUB!
> 
> Whereas with previous grub2.02, I also have the following lines after the
> welcome message:
>   Waiting for Ethernet connection... done.
>   Please press 't' to show the boot menu on this console

Is /sys/firmware/efi present on your the system ? It is required to generate
the relevant message and hiddenentry in grub.cfg ..

[1]
https://build.opensuse.org/package/view_file/openSUSE:Factory/grub2/grub2-SUSE-Add-the-t-hotkey.patch?expand=1

Other possibilities could be the timeout setting, would you please attach your
grub.cfg here for reference ? 

> 
> > If not working, could you please try modifying /etc/default/grub with:
> > 
> >  GRUB_TERMINAL="console"
> > 
> > And run "grub2-mkconfig -o /boot/grub2/grub.cfg" to direct using the
> > firmware console at boot, thus will eliminate the hotkey 't' not being
> > functional. And if still not work, problem might be within the console
> > terminal itself.
> 
> GRUB_TERMINAL="console" option allows to have the menu on serial console.

OK, at least good news for the console driver in 2.04 works.