Linux: How to change the text size or character size in runlevel 3 (text mode)

Posted by Vivek Gite [Last updated: September 6, 2006]

If you have large size (21") or small size (14") monitor, it is better to use large/small character size. But how do you setup character size in runlevel 3 under Linux?

The answer is simple, use the kernel framebuffer. It allows you to set the Linux text scree (console) to higher or lower resolution. The Linux framebuffer (fbdev) is a graphic hardware-independent abstraction layer to show graphics on a console without relying on system-specific libraries such as SVGALib or the heavy overhead of the X Window System.

Open GRUB configuration file grub.conf
# vi grub.conf

Append line vga=0x318 (a 24-bit color depth @ 1024x768 display) to kernel line. At the end your modification should look like as follows:
title Debian Linux, AMD-VSNL (VMWARE) root (hd1,0) kernel /boot/vmlinuz-2.6.17.11-ROCKY-DEV-AMD root=/dev/hdb1 ro vga=0x318 initrd /boot/initrd.img-2.6.17.11-ROCKY-DEV-AMD savedefault boot

Save and close the file. Reboot the system:
# reboot

0x318 (hex) is a mode. Here are common modes:

Colors	640x480	800x600	1024x768
8 bits	0x301	0x303	0x305
16 bits	0x311	0x314	0x317
24 bits	0x312	0x315	0x318

See kernel docs - Documentation/i386/boot.txt and Documentation/svga.txt files for more information. You can also pass special parameter called ask i.e. vga=ask for menu.

Please note that not all video cards out there support kernel framebuffer mode. Also you may need to to use special driver.

References:

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