DRM(4) | Device Drivers Manual | DRM(4)

# NAME

`drm` —
Direct Rendering Manager (DRI kernel support)

# SYNOPSIS

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

`options DRM_DEBUG`
`options DRM_NO_AGP`
`options DRM_MAX_RESOLUTION_HORIZONTAL=integer`
`options DRM_MAX_RESOLUTION_VERTICAL=integer`

# DESCRIPTION

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:

i915drm
  Intel i915, i945
mach64drm
  Mach64 (3D Rage Pro, Rage)
mgadrm
  Matrox G[24]00, G[45]50
r128drm
  ATI Rage 128
radeondrm
  ATI Radeon
savagedrm
  S3 Savage
sisdrm
  SiS
tdfxdrm
  3dfx (Voodoo)
viadrm
  VIA

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.

With some drivers (at least radeon(4)), in some cases the driver does not choose the resolution correctly. The options `DRM_MAX_RESOLUTION_HORIZONTAL` and `DRM_MAX_RESOLUTION_VERTICAL` allow limiting the maximum resolution in X and Y direction.

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"
    EndSection
    ...
    Section "DRI"
            Group "wheel"
            Mode 0660
    EndSection

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.

# SEE ALSO

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

Direct Rendering Infrastructure

# HISTORY

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.

# AUTHORS

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

# CAVEATS

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.

March 10, 2021 | NetBSD 10.1