Setting the resolution or character size for boot and text consoles on SLE 12 and newer

This document (7017979) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server or Desktop versions 12 and newer.

Situation

The auto-detected text based resolution during boot and at text consoles (terminal/tty1-6) may not be optimal and needs to be changed.

Resolution

Grub2 provides settings for the initial screen resolution. A kernel parameter can also be added for the KMS (kernel mode setting) resolution. If the auto-detection of the native resolution is not correct it would be appropriate to use both of these settings (grub2 and kernel parameter).

Both the grub2 settings and the kernel parameter can be added to the grub2 boot loader configuration. Follow these steps as the root user to make the changes:

Edit /etc/default/grub

Locate this line:
GRUB_GFXMODE=auto
Change it to the desired resolution. Lets use an example of 1280x1024:
GRUB_GFXMODE=1280x1024

Look for this entry. If it doesn't exist add it under the GRUB_GFXMODE setting:
GRUB_GFXPAYLOAD=keep

For the kernel parameter locate the line that begins with:
GRUB_CMDLINE_LINUX_DEFAULT=
Go to the end of that line and add this entry (again using 1280x1024 as an example):
video=1280x1024
The full line would look similar to this:

GRUB_CMDLINE_LINUX_DEFAULT="resume=/dev/disk/by-uuid/0e618837-2b33-4ed1-ba0d-ec8b1dfad196 splash=silent quiet showopts crashkernel=97M,high crashkernel=72M,low video=1280x1024"

Save the file then run the following command to write the changes to the grub2 bootloader configuration:

grub2-mkconfig -o /boot/grub2/grub.cfg

Reboot the system to have the changes take effect.

Cause

Additional Information

For systems that are also running a graphic desktop these settings should have no affect on the graphic resolution.

In some cases KMS being enabled causes trouble with the graphic desktop. This is common in VM's and in situations where the hardware is not properly detected for some reason. This may result in adding the kernel parameter "nomodeset" which disables the kernel KMS. In that case the kernel parameter mentioned above "video=1280x1024" (or whatever the desired resolution is) should not be added. KMS is already disabled and will not change the resolution set by the GRUB_GFXMODE setting.

For those that are familiar with the "vga=" parameter used in earlier kernel versions, this setting is depreciated and should no longer be used. It will still work if KMS is disabled but is no longer the preferred method and will be removed eventually.

Disclaimer

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