Manual browser: mgadrm(4)

DRM(4) Kernel Interfaces Manual DRM(4)


drmDirect Rendering Manager (DRI kernel support)


i915drm* at drm?
mach64drm* at drm?
mgadrm* at drm?
r128drm* at drm?
radeondrm* at drm?
savagedrm* at drm?
sisdrm* at drm?
tdfxdrm* at drm?
viadrm* at drm?

options DRM_DEBUG
options DRM_NO_AGP


The Direct Rendering Manager is part of the Direct Rendering Infrastructure for supporting video acceleration (3d acceleration, mostly).

The drm drivers provide support for the following chipsets:

Intel i915, i945
Mach64 (3D Rage Pro, Rage)
Matrox G[24]00, G[45]50
ATI Rage 128
ATI Radeon
S3 Savage
3dfx (Voodoo)

To make use of the driver, the kernel must include agp(4) (for some drivers, using options DRM_NO_AGP instead may be sufficient), X(7) must be compiled with DRI support, Mesa DRI drivers must be installed, the appropriate /dev/dri/card* device must exist, and DRI must be enabled in the X configuration file. X(7) provided with NetBSD and compiled from pkgsrc(7) do so automatically where supported.

X(7) will attempt to create the device node automatically. To create the device node manually:

mkdir -p /dev/dri 
mknod /dev/dri/card0 c 180 0 
chgrp wheel /dev/dri/card0 
chmod 0660 /dev/dri/card0

To enable DRI in the X configuration add the following to either xorg.conf for Xorg(1) or XF86Config for XFree86(1) :

Section "Module" 
        Load  "dri" 
        Load  "dri2" 
        Load  "glx" 
Section "DRI" 
        Group "wheel" 
        Mode 0660 

Debugging output can be enabled and disabled by setting the sysctl(8) node hw.dri.debug. Additional information can be obtained from the sysctl(8) nodes hw.dri, hw.dri.card0, hw.dri.card1, etc.


XFree86(1), Xorg(1), agp(4), XF86Config(5), xorg.conf(5), X(7), /usr/X11R[67]/lib/X11/doc/README.DRI

Direct Rendering Infrastructure


DRM was first available for Linux. Subsequently Eric Anholt ported the DRM kernel modules to FreeBSD. Erik Reid adapted the FreeBSD DRM kernel modules to NetBSD. As DRM continued to develop the NetBSD support was neglected. Tonnerre Lombard got the DRM modules working again, but DRM development once again left the NetBSD support behind. Finally Yorick Hardy took the FreeBSD DRM source and managed to get it compiling and working again on NetBSD, thanks largely to the efforts of all those mentioned above. Subsequently Matthias Drochner improved the DRM file hierarchy for NetBSD and committed the DRM kernel drivers. Matthew Green cleaned up this port and merged a set of newer drivers, with Arto Huusko and FUKAUMI Naoki helping to get the latest Mesa port up to date.

The drm drivers appeared in NetBSD 5.0.


Eric Anholt, Terry Barnaby, Erdi Chen, Michel Daenzer, Leif Delgass, Frank C. Earl, Rickard E. Faith, Jose Fonseca, Nicolai Haehnle, Jeff Hartmann, Thomas Hellstrom, Gareth Hughes, Felix Kuehling, Sung-Ching Lin, Kevin E. Martin, Daryll Strauss, Keith Whitwell


In case of errors, /dev/dri/card0 may be changed, make sure to recreate it in that case.

options DRM_DEBUG can slow DRI down a lot; disable it once drm works.

June 4, 2013 NetBSD 7.0