Hardware 3D Acceleration Guide
What is hardware 3D acceleration and why do I want it?
With hardware 3D acceleration, three-dimensional rendering uses the graphics
processor on your video card instead of taking up valuable CPU resources
drawing 3D images. It's also referred to as "hardware acceleration" instead of
"software acceleration" because without this 3D acceleration your CPU is forced
to draw everything itself using the Mesa software rendering libraries, which
takes up quite a bit of processing power. While Xorg typically supports 2D
hardware acceleration, it often lacks hardware 3D acceleration.
Three-dimensional hardware acceleration is valuable in situations requiring
rendering of 3D objects such as games, 3D CAD and modeling.
How do I get hardware 3D acceleration?
In many cases, both binary and open-source drivers exist. Open source drivers
are preferable since we're using Linux and open source is one of its underlying
principles. Sometimes, binary drivers are the only option, especially if your
graphics card is so new that open source drivers have not yet been written to
support its features. Binary drivers include x11-drivers/nvidia-drivers
for nVidia cards and x11-drivers/ati-drivers for AMD/ATI cards.
What is DRI?
The Direct Rendering
Infrastructure, also known as the DRI, is a framework for allowing direct
access to graphics hardware in a safe and efficient manner. It includes changes
to the X server, to several client libraries and to the kernel. The first major
use for the DRI is to create fast OpenGL implementations.
What is the DRM and how does it relate to regular Xorg?
The DRM (Direct Rendering Manager) is an enhancement to Xorg that adds 3D
acceleration for cards by adding the kernel module necessary for direct
This guide is for people who can't get direct rendering working with just Xorg.
The DRM works for the following drivers:
See the DRI homepage for more info
Install Xorg and configure your kernel
Please read our Xorg Configuration
Guide to get Xorg up and running.
Configure your kernel
Probe for your chipset and enable just that one.
Code Listing 2.1: Checking your AGP chipset
# emerge pciutils; lspci | grep AGP
# 00:01.0 PCI bridge: Intel Corp. 440BX/ZX/DX - 82443BX/ZX/DX AGP bridge (rev 03)
If your chipset is not supported by the kernel you might have some success by
passing agp=try_unsupported as a kernel parameter. This will use Intel's
generic routines for AGP support. To add this parameter, edit your bootloader
Most, if not all, kernels should have these options. This was configured using a
standard gentoo-sources kernel.
Code Listing 2.2: Configuring the kernel
# ls -l /usr/src/linux
lrwxrwxrwx 1 root root 22 2007-02-14 20:12 /usr/src/linux -> linux-2.6.18-gentoo-r4
# cd /usr/src/linux
# make menuconfig
Code Listing 2.3: make menuconfig options
Processor type and features --->
<*> MTRR (Memory Type Range Register) support
Device drivers --->
Graphics support --->
<M> /dev/agpgart (AGP Support) --->
<M> Intel 440LX/BX/GX, I8xx and E7x05 support
<M> Direct Rendering Manager (XFree86 4.1.0 and higher DRI support) --->
Compile and install your kernel
Code Listing 2.4: Compiling and installing kernel
# make && make modules_install
Don't forget to set up grub.conf or lilo.conf and run
/sbin/lilo if you use LILO.
Add your user to the video group
Next, add your user(s) to the video group, as explained in the handbook:
Code Listing 2.5: Adding a user to the video group
# gpasswd -a username video
Configure direct rendering
Hopefully just adding your user to the video group is sufficient to
enable direct rendering. However, you may also need to create a file in
/etc/X11/xorg.conf.d/. You can name it anything you like; just make
sure it ends in .conf. Open up your favorite text editor and create
a file with this inside it:
Code Listing 3.1: /etc/X11/xorg.conf.d/10-dri.conf
Changes to /etc/conf.d/modules
You will need to add the module name that your card uses to
/etc/conf.d/modules to ensure that the module is
loaded automatically when the system starts up.
Code Listing 3.2: Editing /etc/conf.d/modules
If you compiled agpgart as a module, you will also need to add it to
Test 3D acceleration
Reboot to the new kernel
Reboot your computer to your new kernel and login as a normal user. It's time to
see if you have direct rendering and how good it is. glxinfo and
glxgears are part of the mesa-progs package, so make sure it is
installed before you attempt to run these commands.
Code Listing 4.1: Testing rendering
$ glxinfo | grep rendering
direct rendering: Yes
FPS may be limited by your screen's refresh rate, so keep this in mind if
glxgears reports only about 70-100 FPS. games-fps/ut2004-demo or
other 3D games are better benchmarking tools, as they give you real-world
Get the most out of direct rendering
If you want to set more features, for performance or other reasons, check out
matrix on the DRI web site or the features
listing on Sourceforge.
It doesn't work. I don't have rendering, and I can't tell why.
Try modprobe radeon before you start the X server (replace radeon
with the name of your driver). Also, try building agpgart into the kernel
instead of as a module.
When I startx, I get this error: "[drm] failed to load kernel module agpgart"
That's because you compiled agpgart into the kernel instead of as a module.
Ignore it unless you're having problems.
I have a Radeon, and I want TV-Out.
The drivers originally developed by the GATOS project have been merged into Xorg's
codebase. You don't need anything special for TV-Out;
x11-drivers/xf86-video-ati will work just fine.
It doesn't work. My card is so incredibly new and cool that it isn't supported
Try out the binary drivers. For AMD cards, use ati-drivers; a listing is
at http://support.amd.com/us/gpudownload/Pages/index.aspx. If those
don't support it, use fbdev. It's slow, but it works.
I have a PCI card and it doesn't work. Help!
Create a config file in /etc/X11/xorg.conf.d/; name it anything you
want as long as it ends in .conf. Add the following to it:
Code Listing 5.1: /etc/X11/xorg.conf.x/10-pcimode.conf
Option "ForcePCIMode" "True"
With suggestions, questions, etc., e-mail Donnie Berkholz.
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