Grub2 Resolution Question

English Install/Boot/Login
1

Hello I have a question about Grub2. Upon a fresh install of Tumbleweed the resolution on my Grub2 screen is 1920x1080x32. During boot I go into the grub terminal and confirmed it by typing vbeinfo. However because my laptop’s screen brightness stays on max with default settings I am forced to edit file /etc/default/grub. All I do is add “acpi_osi=” to the end of line “GRUB_CMDLINE_LINUX_DEFAULT=” in enable altering my brightness settings.

However, the moment I make any change to /etc/default/grub my grub resolution goes down to 1280x1024x32. I go back into the grub command line and no longer see that 1920x1080x32 is supported. The highest resolution is now 1280x1024x32. I’ve tried updating grub to use the higher resolution that it formerly accepted to no avail. Does anyone know why grub no longer sees the higher resolution by making a simple change to /etc/default/grub?

Thanks.

2

Editing /etc/default/grub have zero impact on grub unless you also re-create grub configuration. Did you do it; if yes how?

It is also quite possible that your original grub.cfg did not use settings from /etc/default/grub. Please paste output of

grep -Ev '^#|^$' /etc/default/grub

in tags code.

3

Thanks for the response. Here’s the output. Again all I did was add “acpi_osi=” to the end of line GRUB_CMDLINE_LINUX_DEFAULT. Then ran ‘grub2-mkconfig -o /boot/grub2/grub.cfg’ to update. After rebooting my resolution downgrades to 1280x1024x32 from 1920x1080x32.

grep -Ev '^#|^$' /etc/default/grub


GRUB_DISTRIBUTOR=""
GRUB_DEFAULT=saved
GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=8
GRUB_CMDLINE_LINUX_DEFAULT="resume=/dev/disk/by-uuid/f18054c0-d1eb-46b7-a265-23407fd0ee83 splash=verbose quiet showopts elevator=deadline acpi_osi="
GRUB_CMDLINE_LINUX_RECOVERY=single
GRUB_CMDLINE_LINUX=""
GRUB_TERMINAL=gfxterm
GRUB_GFXMODE=auto
GRUB_DISABLE_RECOVERY=true
GRUB_DISABLE_OS_PROBER=false
GRUB_ENABLE_CRYPTODISK=n
SUSE_BTRFS_SNAPSHOT_BOOTING=true
GRUB_BACKGROUND=/boot/grub2/themes/openSUSE/background.png
GRUB_THEME=/boot/grub2/themes/openSUSE/theme.txt

It’s interesting that you say: “It is also quite possible that your original grub.cfg did not use settings from /etc/default/grub”. I hadn’t ever thought of that. I installed tumbleweed via USB stick. I wonder if the original grub.cfg is on there and thus when I finally remove the stick it falls back to /etc/default/grub. What is weird is that when I was on 13.1 grub always defaulted to 1920x1080x32.

4

I happened to save my grub file from my old 13.1 installation. It is much more complex than my Tumbleweed grub file. I wonder if one of the additional parameters in 13.1 forced to correct resolution.

13.1


GRUB_CMDLINE_LINUX_DEFAULT=" BOOT_IMAGE=/multiboot/openSUSE-13.1-KDE-Live-x86_64/linux initrd=/multiboot/openSUSE-13.1-KDE-Live-x86_64/initrd ramdisk_size=512000 ramdisk_blocksize=4096 isofrom=/dev/disk/by-label/MULTIBOOT:/multiboot/openSUSE-13.1-KDE-Live-x86_64/openSUSE-13.1-KDE-Live-x86_64.iso isofrom_device=/dev/disk/by-label/MULTIBOOT isofrom_system=/multiboot/openSUSE-13.1-KDE-Live-x86_64/openSUSE-13.1-KDE-Live-x86_64.iso loader=syslinux resume=/dev/sda5 splash=silent quiet showopts"

Tumbleweed


GRUB_CMDLINE_LINUX_DEFAULT="resume=/dev/disk/by-uuid/f18054c0-d1eb-46b7-a265-23407fd0ee83 splash=verbose quiet showopts elevator=deadline acpi_osi="
5

Just to be sure - you mean resolution in GRUB menu screen, or after kernel is loaded?

6

Yes. I’m referring to Grub menu resolution.

7

I really do not see what could affect resolution here. Unfortunately we do not have old grub.cfg so cannot really compare.

Try going in command line in GRUB (press “c” when bootloader menu is displayed) and run videoinfo command. Is your desired resolution displayed there? You may want to enable pager as output may exceed one screen: set pager=1.