UB
Universal Blue•2mo ago
CaptainN

How to reduce grub resolution?

On my 4k laptop, I have 2 problems: 1) the grub boot menu is in 4k - so it's all super tiny. 2) If I have TPM and secure boot enabled, it actually runs out of memory, and I've heard you can lower the resolution to fix that. So how do I do that on Bazzite? Most of the stuff the AIs tell me is bunk, and doens't work.
Solution:
I added this to /etc/default/grub: 
GRUB_GFXMODE="1920x1080x32,1280x720x32,1024x768x32,800x600x32,640x480x32,auto"
GRUB_GFXMODE="1920x1080x32,1280x720x32,1024x768x32,800x600x32,640x480x32,auto"
Then ran the generate command:...
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17 Replies
CaptainN
CaptainNOP•2mo ago
There are so many notes all over the grub files about what NOT to edit, but nothing about how to actually get any custom settings in to the darned runtime config. NOTHING I do makes it in. It's like trying to send a signal from the event horizon of a black hole.
biebel
biebel•2mo ago
CaptainN
CaptainNOP•2mo ago
That is one of the many things I've tried, 36 different times lol Nothing has any impact at all - it just always renderes at 4k I think it's because the way the grub.cfg is generated, it doesn't load any of the custom stuff until all the way at the end - after the video mode is already initialized. For me, changing it back won't actually solve the problem - I need it to never try to run in 4k at all And there doesn't appear to be any way to actually override that early enough with custom configs (And changing the mode after the fact just doesn't work - ever.) grub's terminal is also missing commands like videoinfo
biebel
biebel•2mo ago
Not sure how it works in current linux, but I used to do some nomodset kernel argument thing a long time ago. This was in crt times though. I'll see if I can dig sth up
CaptainN
CaptainNOP•2mo ago
I also tried changing kernal args, that also has no impact whatsoever It's definitely probable I've done it wrong It looks equally probable, that there just isn't a way to override the mode setting (on silverblue/ostree base)
biebel
biebel•2mo ago
You can set a manual resolution for sure. Helped someone with that before. You need to use rpm-ostree kargs for kernel arguments. Not sure how it applies to an internal monitor though. They used a manual resolution from here: https://wiki.archlinux.org/title/Kernel_mode_setting#Troubleshooting
CaptainN
CaptainNOP•2mo ago
The grub template system sets the display mode in it's 00 file: 
### BEGIN /etc/grub.d/00_header ###
set pager=1

if [ -f ${config_directory}/grubenv ]; then
  load_env -f ${config_directory}/grubenv
elif [ -s $prefix/grubenv ]; then
  load_env
fi
if [ "${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 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 loadfont unicode ; then
  set gfxmode=auto
  load_video
  insmod gfxterm
  set locale_dir=$prefix/locale
  set lang=en_US
  insmod gettext
fi
terminal_output gfxterm
if [ x$feature_timeout_style = xy ] ; then
  set timeout_style=menu
  set timeout=5
# Fallback normal timeout code in case the timeout_style feature is
# unavailable.
else
  set timeout=5
fi
### END /etc/grub.d/00_header ###
### BEGIN /etc/grub.d/00_header ###
set pager=1

if [ -f ${config_directory}/grubenv ]; then
  load_env -f ${config_directory}/grubenv
elif [ -s $prefix/grubenv ]; then
  load_env
fi
if [ "${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 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 loadfont unicode ; then
  set gfxmode=auto
  load_video
  insmod gfxterm
  set locale_dir=$prefix/locale
  set lang=en_US
  insmod gettext
fi
terminal_output gfxterm
if [ x$feature_timeout_style = xy ] ; then
  set timeout_style=menu
  set timeout=5
# Fallback normal timeout code in case the timeout_style feature is
# unavailable.
else
  set timeout=5
fi
### END /etc/grub.d/00_header ###
hmm, if loadfont unicode - how do I change that conditional? I wonder if I can just edit the 00_header file?
biebel
biebel•2mo ago
You should be able to as it's on /etc
CaptainN
CaptainNOP•2mo ago
BTW, I tried setting kargs 100 different ways - nothing had any impact also, hwinfo --framebuffer doesn't work on bazzite and in grub cli, neither videoinfo and vbeinfo aren't there either It's like everything that might be somewhat standard in the linux world is simply unavailable here
biebel
biebel•2mo ago
I've never bothered to figure out the complete grub chain, but all kernel parameters that I tried with kargs worked. The person I helped setting a manual reolution for their tv with a karg had success too.
CaptainN
CaptainNOP•2mo ago
It looks like the 00_header file actually sets the mode from a variable can I just enter this in grubenv maybe?
biebel
biebel•2mo ago
CaptainN
CaptainNOP•2mo ago
Cool thanks! I don't know what I did differently this time, but it worked!
Solution
CaptainN
CaptainN•2mo ago
I added this to /etc/default/grub: 
GRUB_GFXMODE="1920x1080x32,1280x720x32,1024x768x32,800x600x32,640x480x32,auto"
GRUB_GFXMODE="1920x1080x32,1280x720x32,1024x768x32,800x600x32,640x480x32,auto"
Then ran the generate command: 
sudo grub2-mkconfig -o /boot/grub2/grub.cfg
sudo grub2-mkconfig -o /boot/grub2/grub.cfg
CaptainN
CaptainNOP•2mo ago
I think the mistake I made earlier, was that I didn't include x32 in the mode list Anyway - this works!
CaptainN
CaptainNOP•2mo ago
It did NOT solve the out of memory problem lol - I'll try other things later
biebel
biebel•4w ago
Not sure if this applies to you, but I just came across this grub oom thread: https://universal-blue.discourse.group/t/stuck-on-bazzite-build-cant-boot-into-update-grub-memory-error-others-affected/6827
Universal Blue
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