Revision as of 02:46, August 2, 2014 by Duncan.britton (Talk | contribs) (Back to kernel configuration)

How to : Framebuffer: Userspace VESA VGA graphics support

Uvesafb is an improved framebuffer driver for Linux systems with some enhancements compared to vesa. Uvesafb can allow you to get a full-resolution console, even if you have installed a graphics driver that does not support full-resolution consoles. Examples of drivers like these: ati-drivers and NVidia-drivers.

Kernel configuration

Before we emerge the required packages for uvesafb functionality, we have to configure the kernel properly.

Device Drivers --->
    <*> Connector - unified userspace <-> kernelspace linker  --->

    Graphics support --->
        Frame buffer devices --->
        [*] Support for frame buffer devices  --->
            [*] Enable firmware EDID
            <*> Userspace VESA VGA graphics support
Build the kernel (make), do not install the kernel and modules ( make install modules_install). You can choose uvesafb as a module, unlike vesa.


Next, we emerge dev-libs/klibc (package not on wiki - please add). Klibc has to be compiled against a kernel that includes uvesafb support. This only has to be done once:

# emerge klibc


sys-apps/v86d (package not on wiki - please add) is the userspace helper that runs x86 code in emulated environment. Uvesafb will not work without v86d. Emerge v86d:

# emerge v86d

Back to kernel configuration

Reconfigure the kernel to include /usr/share/v86d/initramfs as an initramfs source file:

General Setup--->
    [*] Initial RAM filesystem and RAM disk (initramfs/initrd) support
    (/usr/share/v86d/initramfs)    Initramfs source file(s)

Rebuild the kernel: make and install it, install the modules

Bootloader configuration

If you compiled uvesafb into the kernel (not as a module), you can configure its behavior by editing the 'params += ' line in /etc/boot.conf. Below, some of the more common switches used with uvesafb are explained.

  • video=uvesafb:<screen y-res>x<screen x-res>-<color depth>: Tells the kernel that you want to use the uvesafb driver for console output. Also specifies that you will be using uvesafb at a set x-screen resolution, y screen-resolution, and color depth. Set the first part to the size of your screen (in pixels). For example, if I had a 1920x1080 screen and wanted a color depth of 32, I would add the following: video=uvesafb:1920x1080-32
  • mtrr:x: X represents the number 0 or 3. This option allows you to set up the memory type range registers for uvesafb. Setting x=0 disables mtrr and setting x=3 enables mtrr. x=3 is the default setting for this switch. mtrr:3 is recommended.
  • ywrap: Add support for display panning. Recommended.
For more information regarding these switches, check out http://www.mjmwired.net/kernel/Documentation/fb/uvesafb.txt

Now that you have a basic understanding of these different switches, configure your /etc/boot.conf:

boot {
        generate grub
        default "Funtoo Linux: uvesafb" 
        timeout 3 
  "Funtoo Linux: uvesafb" { 
        kernel bzImage[-v]
        params += video=uvesafb:1920x1080-32,mtrr:3,ywrap
Realize that the configuration in the above file will not work on every computer. You must change the resolution (and possibly other switches) to best suite your needs.

After you have finished editing your /etc/boot.conf, run the following:

# boot-update

finally, reboot your computer so that you can test out uvesafb:

# reboot