Framebuffer Console

framebuffer console is an alternative to the regular text mode console. it allows a high-resolution console on your linux machine. it can be enabled by default on most systems by passing a parameter to the kernel on boot.

use with caution. possible damage to monitor if you invoke an unsupported mode.

• Option (1): Use the vga boot parameter (recommended)
• Option (2): Use the SVGATextMode package

If you add the following to your kernel line in your bootloader, it will cause the system to prompt you on each boot for the framebuffer mode.

vga=ask

better yet, pass the frame buffer mode directly to your kernel without causing the machine to pause and prompt you. the following are options:

# VESA framebuffer console @ 1024x768x256
vga = 773
# Normal VGA console
# vga = normal
# VESA framebuffer console @ 1024x768x64k
# vga=791
# VESA framebuffer console @ 1024x768x32k
# vga=790
# VESA framebuffer console @ 1024x768x256
# vga=773
# VESA framebuffer console @ 800x600x64k
# vga=788
# VESA framebuffer console @ 800x600x32k
# vga=787
# VESA framebuffer console @ 800x600x256
# vga=771
# VESA framebuffer console @ 640x480x64k
# vga=785
# VESA framebuffer console @ 640x480x32k
# vga=784
# VESA framebuffer console @ 640x480x256
# vga=769 

If you pass an unsupported framebuffer mode for your system you will get the error below:

resume=/dev/hda2
  [Linux-bzImage, setup=0x1600, size=0x15a1d5]
initrd (hd0,2)/boot/initrd
  [Linux-initrd @ 0x17e8e000, 0x15f807 bytes]

You passed an undefined mode number.
Press <RETURN> to set video mode number.
<SPACE> to continue or wait 30 secs

Video Adapter: VESA VGA
Mode: COLSxROWS:
0 0F00 80x25
1 0F01 80x50
2 0F02 80x43
3 0F03 80x28
4 0F05 80x30
5 0F06 80x34
6 0F07 80x60
7 030A 132x43 

You may have to keep trying until you find the framebuffer mode that is supported.

SVGATextMode is a utility for reprogramming (S)VGA hardware, to improve the appearance of text consoles. SVGATextMode uses a configuration file (the default is /etc/TextConfig) with a syntax similar to X Window System's configuration file (Xconfig or XF86Config) to set up textmodes with higher resolution, larger font sizes, higher display refresh rates, etc. Theoretically, SVGATextMode can be used to program any text mode size, but your results will depend upon your VGA card.

For a redhat system:

rpm -ivh SVGATextMode-VERSION.rpm

determine the Horizontal Sync and Vertical Refresh capabilities of your monitor. If you already have X configured, you can easily look through your XF86Config or XMetroConfig (if using Metro-X) files for the HorizSync and VertRefresh lines. For example:

     [kwan@omicron]  egrep -i 'horizsync|vertrefresh' /etc/X11/XF86Config
     HorizSync    30-0 - 97.0
     VertRefresh  48.0 - 129.0
   

Configure the /etc/TextConfig file

# Chipset "VGA"
# Clocks  25.175 28.322

comment out the warning sectin too

Thu Apr 6 11:50:55 CDT 2006