Xorg/Hardware 3D acceleration guide
This document is a guide to getting 3D acceleration working using the DRM with Xorg in Gentoo.
What is hardware 3D acceleration and why do I want it?
With hardware 3D acceleration, three-dimensional rendering uses the graphics processor on the 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 the 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.
Getting 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 the 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/xf86-video-ati (used to be x11-drivers/ati-drivers) for older AMD/ATI cards, dev-libs/amdgpu-pro-opencl for newer AMD 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 rendering.
This guide is for people who can't get direct rendering working with just Xorg. The DRM works for the following drivers:
- amdgpu-pro (closed source)
- fglrx (closed source; deprecated)
- nvidia-drivers (closed source)
- radeonhd (deprecated)
See the DRI homepage for more info and documentation.
Install Xorg and configure the kernel
Please read our Xorg Configuration Guide to get Xorg up and running.
Configure the kernel
Probe for the specifics of the relevant hardware.
emerge --ask sys-apps/pciutils
lspci | grep -Ei "VGA|AGP|3D"
# 00:01.0 PCI bridge: Intel Corp. 440BX/ZX/DX - 82443BX/ZX/DX AGP bridge (rev 03)
The output may not match the above due to different hardware, whatever is returned will help inform the user as to what kernel options to consider.
Certain kernel options will be required, others may cause problems. Hardware specific resources concerning which kernel option for which hardware exist within this wiki and elsewhere.
It is possible however unlikely that the given command returns nothing at all. In this case, the whole output of lspci -nnk would be a good bit of information to review and/or to pass along when seeking help.
In the given example, where the chipset is an AGP chipset, but a different one unsupported by the kernel, some success may be obtained by passing
agp=try_unsupported as a kernel parameter. This will use Intel's generic routines for AGP support. To add this parameter, edit the bootloader's configuration file. Again, required kernel config options and available bootloader parameters will vary based on hardware specifics.
Before proceeding to change any kernel options, if necessary, make sure /usr/src/linux links to the intended kernel:
ls -dl /usr/src/linux*
lrwxrwxrwx 1 root root 19 Feb 16 16:30 /usr/src/linux -> linux-5.4.18-gentoo drwxr-xr-x 27 root root 4096 Feb 16 21:27 /usr/src/linux-4.19.103-gentoo
In order to update the symlink to another target, use these commands. The second command takes an argument from the options displayed in the output of the first:
eselect kernel list
eselect kernel set
With the symlink verified, to adjust kernel options:
Most, if not all, kernels should have these options set. In any case, options labeled <M> are compiled as modules and loaded-as-necessary, thus being very unlikely to break anything if not required.
This was configured using a standard sys-kernel/gentoo-sources kernel.
Processor type and features ---> <*> MTRR (Memory Type Range Register) support Device drivers ---> Graphics support ---> <M> /dev/agpgart (AGP Support) ---> (The agpgart option is not present on 64-bit kernels; just choose the appropriate chipset support.) <M> Intel 440LX/BX/GX, I8xx and E7x05 support (Enable the appropriate chipset instead of the above.) <M> Direct Rendering Manager (XFree86 4.1.0 and higher DRI support) ---> <M> (Select the appropriate graphics card from the list)
Compile and install the kernel
make && make install && make modules_install
Don't forget to set up grub.conf or lilo.conf.
When using LILO, issue:
When using GRUB 2, run:
grub-mkconfig -o /boot/grub/grub.cfg
Add appropriate user(s) to the video group
Next, add the appropriate user(s) to the video group:
gpasswd -a $USER video
Configure direct rendering
Hopefully just adding the appropriate user to the
video group is sufficient to enable direct rendering. However, Xorg may need some additional configuration via the /etc/X11/xorg.conf.d/ directory. New configuration files created in this directory may be named any alpha-numeric file name, as long as the file suffix ends in .conf. Open up a favorite text editor and create a file with this inside it:
Section "Device" Driver "radeon" EndSection Section "dri" Mode 0666 EndSection
radeon with the name of the appropriate driver.
Changes to automatic module loading
You will need to add the module name that your card uses to /etc/modules-load.d/video.conf to ensure that the module is loaded automatically when the system starts up.
intel-agp # Substitute with your driver
If you compiled
agpgartas a module, you will also need to add it to /etc/modules-load.d/video.conf.
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.
glxgears are part of the x11-apps/mesa-progs package, so make sure it is installed before you attempt to run these commands.
No need to load modules for your driver or agpgart, even if you compiled them as a module. They will be loaded automatically.
glxinfo | grep rendering
direct rendering: Yes
If it outputs "No", you don't have 3D acceleration.
Test your frames per second (FPS) at the default size. The number should be significantly higher than before configuring DRM. Do this while the CPU is as idle as possible.
FPS may be limited by your screen's refresh rate, so keep this in mind if
glxgearsreports only about 70-100 FPS. games-fps/xonotic or other 3D games are better benchmarking tools, as they give you real-world performance results.
Get the most out of direct rendering
Problem with rendering
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.
Failed to load kernel module agpgart when running startx
error: "[drm] failed to load kernel module agpgart" after invoking `startx` is caused by presents of compiled agpgart in the kernel instead of as a module. Ignore it unless you're having problems.
TV-Out on Radeon GPU
Compatibility for freshly released GPUs
Try out the binary drivers. For AMD cards, use
ati-drivers. If those don't support it, use fbdev. It's slow, but it works.
PCI card doesn't work properly
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:
Section "Device" Option "ForcePCIMode" "True" EndSection
- Direct rendering (DRI) using X11-DRM HOWTO on the Gentoo forums
- Radeon 7000-9700 DRI CVS Install Guide on the Gentoo forums
This page is based on a document formerly found on our main website gentoo.org.
The following people contributed to the original document: Donnie Berkholz (dberkholz), peesh,
They are listed here because wiki history does not allow for any external attribution. If you edit the wiki article, please do not add yourself here; your contributions are recorded on each article's associated history page.