flicker-free boot gets interrupted by GRUB menu

[John Jacob]

I have a Dell XPS 9300 running Ubuntu 20.04. I have installed Ubuntu using full disk encryption as documented at https://help.ubuntu.com/community/Full_Disk_Encryption_Howto_2019

When I power on my laptop, I get the Dell boot logo and GRUB prompt asking me to enter the hard drive decrypt password. After entering the password, after the decrypt completes, the screen displays a GRUB boot options menu. After I hit enter, the Dell boot logo and the spinning Ubuntu logo are displayed again continue until the login screen is displayed.

Ideally, the GRUB menu should not be displayed, so that the whole boot process is flicker free. The menu is (afaict) being shown by the following code in /boot/grub/grub.cfg :
---
if [ "${recordfail}" = 1 ] ; then
  set timeout=30
else
  if [ x$feature_timeout_style = xy ] ; then
    set timeout_style=hidden
    set timeout=0
  # Fallback hidden-timeout code in case the timeout_style feature is
  # unavailable.
  elif sleep --interruptible 0 ; then
    set timeout=0
  fi
fi
if [ $grub_platform = efi ]; then
  set timeout=30
  if [ x$feature_timeout_style = xy ] ; then
    set timeout_style=menu
  fi
fi
---
The last if condition appears to force displaying the menu if the boot mode is EFI. I do not understand why this is necessary.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: grub-common 2.04-1ubuntu26
ProcVersionSignature: Ubuntu 5.4.0-29.33-generic 5.4.30
Uname: Linux 5.4.0-29-generic x86_64
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Mon May 11 18:52:55 2020
InstallationDate: Installed on 2020-04-23 (18 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: grub2
UpgradeStatus: No upgrade log present (probably fresh install)

[Sebastien Bacher (seb128)]

Thank you for your bug report. Could you maybe make a video from the system boot? The password should be asked by plymouth nor grub but it's difficult to say if that's what is happening from the bug description
Could you also add your 'journalctl -b 0' log from a boot having the issue? do you have other another OS installed?

[John Jacob (johnjacob10)]

Hi Sebastien, thank you for looking at my bug report.

I have taken a video of the boot, and I am attaching it.

The video was taken immediately after entering the passphrase at the GRUB prompt. The prompt at the top left corner of the screen, says "Attempting to decrypt master key. Please enter passphrase for hd0,gpt1". Remember, I have /boot encrypted and I'm using GRUB's cryptomount as documented in the wiki at https://help.ubuntu.com/community/Full_Disk_Encryption_Howto_2019

I'm certain the password prompt is from GRUB, as if I enter the wrong password, I get dropped into a GRUB shell.

At the eight second mark, you can see the GRUB menu pop up. When I hit enter to select "Ubuntu", the menu disappears and the Dell logo comes back on the screen.

[John Jacob (johnjacob10)]

Here is the journalctl log.

[John Jacob (johnjacob10)]

I'm having trouble attaching the boot video. It's only 104MB, but Launchpad keeps error-ing out when I upload. I'll keep trying, but is there some other way to get it to you?

[John Jacob (johnjacob10)]

Boot video.

[John Jacob (johnjacob10)]

There is no other OS instaled.

[John Jacob (johnjacob10)]

Provided the information requested. Therefore changing the bug status to New as per FAQ in https://wiki.ubuntu.com/Bugs/Bug%20statuses
"Should the original reporter reset the report status to "New" if providing more information to an "Incomplete" report?
Yes."

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Niklas Sombert (ytvwld)]

I have the same problem.

I guess this relates to https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/425979?

[Mate Kukri (mkukri)]

Encrypted /boot isn't a supported configuration and may break on upgrades.

Please use the password based or TPM FDE options provided by the ubuntu installer.

While I am closing this as 'Won't Fix', if you have a non-invasive patch for this, I am open to reviewing it.