Comment # 18 on bug 1122614 from Michael Chang

(In reply to Guillaume GARDET from comment #13)

> But it does not help. Even copying /usr/share/grub2/arm-efi/grub.efi does
> not show the grub menu on serial. So, maybe some drivers are missing/broken?

The git-log did not reveal upstream serial driver for efi received any change
since 2.02

> git --no-pager log --oneline 2.02..grub-2.04 -- grub-core/term/serial.c grub-core/term/efi/serial.c

Also the firmware's console driver has no obvious change.

> git --no-pager log --oneline 2.02..grub-2.04 -- grub-core/term/efi/console.c
> edece25a7 efi/console: Fix the "enter" key not working on x86 tablets
> bdd89d239 core: use GRUB_TERM_ definitions when handling term characters

Also checked the Makefile.core.def, moddep.lst did not change for the platform
module in use and dependency wrt arm-efi console/serial driver.

Would you please attach grub.cfg for reference ? Maybe can find some clue
there. Meanwhile I'll try to get RPI2 to reproduce the problem.