installed GRUB menu does not appear on term used for install

I've found that the offending line in /boot/grub/grub.cfg is:

terminal_output gfxterm

Prior to that, my active input and output terminals are set to "console". If I comment out that line, I can interact with the installed GRUB over both the serial and VGA consoles, just like with d-i.

I'm not sure what the right solution is. One option is to change:
  terminal_output gfxterm
    to:
  terminal_output --append gfxterm

That makes both "console" and "gfxterm" active. But, maybe it makes more sense to just not emit the "terminal_output gfxterm" under certain conditions. Does gfxterm have any effect on other UEFI-based systems?

Posted a patch upstream for feedback:
  http://lists.gnu.org/archive/html/grub-devel/2018-01/msg00010.html

This bug was fixed in the package grub2 - 2.02-2ubuntu6

---------------
grub2 (2.02-2ubuntu6) bionic; urgency=medium

  [ Steve Langasek ]
  * debian/patches/bufio_sensible_block_sizes.patch: Don't use arbitrary file
    fizes as block sizes in bufio: this avoids potentially seeking back in
    the files unnecessarily, which may require re-open files that cannot be
    seeked into, such as via TFTP. (LP: #1743249)

 -- Mathieu Trudel-Lapierre <email address hidden> Mon, 05 Feb 2018 11:58:09 -0500

Hello dann, or anyone else affected,

Accepted grub2 into artful-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/grub2/2.02~beta3-4ubuntu7.2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-artful to verification-done-artful. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-artful. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

Hello dann, or anyone else affected,

Accepted grub2-signed into artful-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/grub2-signed/1.85.2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-artful to verification-done-artful. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-artful. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

Verified by:
  - MAAS installing a Cavium ThunderX2 Sabre
  - Removing /etc/default/grub.d/50-curtin-settings.cfg (which forces on console mode)
  - Commenting out the HIDDEN settings from /etc/default/grub
  - sudo dpkg-reconfigure grub-arm64-efi (enable NVRAM variables - MAAS disables this)
  - reboot - verify that the GRUB menu does *not* appear
  - upgrade to -proposed GRUB packages
  - verify that GRUB menu *does* appear now

The verification of the Stable Release Update for grub2 has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

This bug was fixed in the package grub2 - 2.02~beta3-4ubuntu7.2

---------------
grub2 (2.02~beta3-4ubuntu7.2) artful; urgency=medium

  * debian/patches/mkconfig_keep_native_term_active.patch: Keep the
    default EFI console active while enabling gfxterm. (LP: #1743884)

 -- dann frazier <email address hidden> Fri, 09 Feb 2018 11:45:07 -0700

The released fix for this introduced a regression (LP: #1752767), so I'm reverting while we seek a better fix.