GRUB_GFXMODE no longer supports high resolution since upgrading to 2.02~beta3-4ubuntu7.2

[Gargoyle]

For months, my EFI grub has been happy to accept GRUB_GFXMODE=2560x1440 (my monitor native resolution).

However, since the recent update to 2.02~beta3-4ubuntu7.2, all I get is a < 1s flash of the high resolution version (with background image) then it falls back to white on grey.

If I comment out the GRUB_GFXMODE and GRUB_BACKGROUND lines, and "update-grub", I get a low resolution version with the background image still in place, and some flickering text artefacts.

With the config as show below with GRUB_GFXMODE=1024x768 and GRUB_BACKGROUND="..." I get a working grub, although at a lower resolution which looks a bit crappy.

Although this might seem a fairly trivial bug in terms of actual impact, I do have a dual boot machine and I hop between Linux and Windows a few times a day, and I like it when grub looks nice and crisp.

System is an AMD Ryzen 1800X, Hero Vi Motherboard and Nvidia 1080Ti GFX card.

➜ ~ apt-cache policy grub-efi-amd64
grub-efi-amd64:
  Installed: 2.02~beta3-4ubuntu7.2
  Candidate: 2.02~beta3-4ubuntu7.2
  Version table:
 *** 2.02~beta3-4ubuntu7.2 500
        500 http://gb.archive.ubuntu.com/ubuntu artful-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     2.02~beta3-4ubuntu7 500
        500 http://gb.archive.ubuntu.com/ubuntu artful/main amd64 Packages

➜ ~ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 17.10
Release: 17.10
Codename: artful

➜ ~ cat /etc/default/grub
 # If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
# info -f grub -n 'Simple configuration'

GRUB_DEFAULT=saved
GRUB_SAVEDEFAULT=true
#GRUB_HIDDEN_TIMEOUT=0
#GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=10
GRUB_TIMEOUT_STYLE=menu
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
GRUB_GFXMODE=1024x768
GRUB_BACKGROUND="/boot/grub/grub_background.png"

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"

[Gargoyle (g-rgoyle)]

The fix for removing the "--append" flag in https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1752767 also fixes this.

I removed the flag from /etc/grub.d/00_header and updated and on the next reboot, grub was happily running at 2560x1440 (and with a background image).