OK I just tried the suggestion mentioned in that thread and added
Code:
GRUB_TERMINAL=console
to /etc/default/grub and ran a sudo update-grub after that.
Curiously I now again have a roughly 30 to 40 second long white-screen on boot!! Makes me wonder if my original problem wasn't caused by Apple firmware but by grub all along. I have really no idea what's going on anymore.
Commenting out the GRUB_TERMINAL=console restores the previous error message screen.
Addendum:
After doing some more researach and finding this article on help.ubuntu.com about UEFI Booting, I followed their advice and added these two commands to the top of my /boot/grub/grub.cfg
Code:
set debug=video
insmod efi_gop
I now get the following messages displayed on screen for about 10 seconds:
Code:
video/efi_gop.c:87: GOP: found usable mode
error: no server is specified.
video/efi_gop.c:388: GOP: beeping mode 0
video/efi_gop.c:439: GOP: initialising FB @ 0xc0010000 1920x1200x32
video/efi_gop.c:516: GOP: Success
Normally I wouldn't care too much as the system is working otherwise, but this error screen slows down the boot process by a good 10 seconds and it won't even go away when pressing ENTER or ESCAPE.
I'm posting my /boot/grub/grub.cfg below, I think the culprit must be in there somewhere and something in there must also be causing the error: no server is specified. message.
Code:
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#
set debug=video
insmod efi_gop
### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
set have_grubenv=true
load_env
fi
if [ "${initrdfail}" = 2 ]; then
set initrdfail=
elif [ "${initrdfail}" = 1 ]; then
set next_entry="${prev_entry}"
set prev_entry=
save_env prev_entry
if [ "${next_entry}" ]; then
set initrdfail=2
fi
fi
if [ "${next_entry}" ] ; then
set default="${next_entry}"
set next_entry=
save_env next_entry
set boot_once=true
else
set default="0"
fi
if [ x"${feature_menuentry_id}" = xy ]; then
menuentry_id_option="--id"
else
menuentry_id_option=""
fi
export menuentry_id_option
if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi
function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}
function initrdfail {
if [ -n "${have_grubenv}" ]; then if [ -n "${partuuid}" ]; then
if [ -z "${initrdfail}" ]; then
set initrdfail=1
if [ -n "${boot_once}" ]; then
set prev_entry="${default}"
save_env prev_entry
fi
fi
save_env initrdfail
fi; fi
}
function recordfail {
set recordfail=1
if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}
function load_video {
if [ x$feature_all_video_module = xy ]; then
insmod all_video
else
insmod efi_gop
insmod efi_uga
insmod ieee1275_fb
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
fi
}
if [ x$feature_default_font_path = xy ] ; then
font=unicode
else
insmod part_gpt
insmod ext2
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 761584f6-29e7-446a-8a8f-ea421eeacc28
else
search --no-floppy --fs-uuid --set=root 761584f6-29e7-446a-8a8f-ea421eeacc28
fi
font="/usr/share/grub/unicode.pf2"
fi
if loadfont $font ; then
set gfxmode=640x480
load_video
insmod gfxterm
set locale_dir=$prefix/locale
set lang=de_DE
insmod gettext
fi
terminal_output gfxterm
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
### END /etc/grub.d/00_header ###
### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
### END /etc/grub.d/05_debian_theme ###
### BEGIN /etc/grub.d/10_linux ###
function gfxmode {
set gfxpayload="${1}"
if [ "${1}" = "keep" ]; then
set vt_handoff=vt.handoff=7
else
set vt_handoff=
fi
}
if [ "${recordfail}" != 1 ]; then
if [ -e ${prefix}/gfxblacklist.txt ]; then
if [ ${grub_platform} != pc ]; then
set linux_gfx_mode=keep
elif hwmatch ${prefix}/gfxblacklist.txt 3; then
if [ ${match} = 0 ]; then
set linux_gfx_mode=keep
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=keep
fi
else
set linux_gfx_mode=text
fi
export linux_gfx_mode
menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-761584f6-29e7-446a-8a8f-ea421eeacc28' {
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_gpt
insmod ext2
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 761584f6-29e7-446a-8a8f-ea421eeacc28
else
search --no-floppy --fs-uuid --set=root 761584f6-29e7-446a-8a8f-ea421eeacc28
fi
linux /boot/vmlinuz-5.19.0-32-generic root=UUID=761584f6-29e7-446a-8a8f-ea421eeacc28 ro quiet splash $vt_handoff
initrd /boot/initrd.img-5.19.0-32-generic
}
submenu 'Advanced options for Ubuntu' $menuentry_id_option 'gnulinux-advanced-761584f6-29e7-446a-8a8f-ea421eeacc28' {
menuentry 'Ubuntu, with Linux 5.19.0-32-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.19.0-32-generic-advanced-761584f6-29e7-446a-8a8f-ea421eeacc28' {
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_gpt
insmod ext2
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 761584f6-29e7-446a-8a8f-ea421eeacc28
else
search --no-floppy --fs-uuid --set=root 761584f6-29e7-446a-8a8f-ea421eeacc28
fi
echo 'Loading Linux 5.19.0-32-generic ...'
linux /boot/vmlinuz-5.19.0-32-generic root=UUID=761584f6-29e7-446a-8a8f-ea421eeacc28 ro quiet splash $vt_handoff
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-5.19.0-32-generic
}
menuentry 'Ubuntu, with Linux 5.19.0-32-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.19.0-32-generic-recovery-761584f6-29e7-446a-8a8f-ea421eeacc28' {
recordfail
load_video
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_gpt
insmod ext2
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 761584f6-29e7-446a-8a8f-ea421eeacc28
else
search --no-floppy --fs-uuid --set=root 761584f6-29e7-446a-8a8f-ea421eeacc28
fi
echo 'Loading Linux 5.19.0-32-generic ...'
linux /boot/vmlinuz-5.19.0-32-generic root=UUID=761584f6-29e7-446a-8a8f-ea421eeacc28 ro recovery nomodeset dis_ucode_ldr
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-5.19.0-32-generic
}
}
### END /etc/grub.d/10_linux ###
### BEGIN /etc/grub.d/10_linux_zfs ###
### END /etc/grub.d/10_linux_zfs ###
### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###
### BEGIN /etc/grub.d/20_memtest86+ ###
### END /etc/grub.d/20_memtest86+ ###
### BEGIN /etc/grub.d/30_os-prober ###
### END /etc/grub.d/30_os-prober ###
### BEGIN /etc/grub.d/30_uefi-firmware ###
### END /etc/grub.d/30_uefi-firmware ###
### BEGIN /etc/grub.d/35_fwupd ###
### END /etc/grub.d/35_fwupd ###
### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###
### BEGIN /etc/grub.d/41_custom ###
if [ -f ${config_directory}/custom.cfg ]; then
source ${config_directory}/custom.cfg
elif [ -z "${config_directory}" -a -f $prefix/custom.cfg ]; then
source $prefix/custom.cfg
fi
### END /etc/grub.d/41_custom ###