man/man4/drm.4

.\"	$NetBSD: drm.4,v 1.7 2009/05/12 08:16:46 wiz Exp $
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.\" Copyright (c) 2007 Thomas Klausner
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.Dd January 11, 2012
.Dt DRM 4
.Os
.Sh NAME
.Nm drm
.Nd Direct Rendering Manager (DRI kernel support)
.Sh SYNOPSIS
.Cd device drm
.Cd device i915drm
.Cd device mach64drm
.Cd device mgadrm
.Cd device r128drm
.Cd device radeondrm
.Cd device savagedrm
.Cd device sisdrm
.Cd device tdfxdrm
.\".Cd device viadrm
.Pp
.Cd options DRM_DEBUG
.\".Cd options DRM_LINUX
.Sh DESCRIPTION
The
.Tn Direct Rendering Manager
is part of the
.Tn Direct Rendering Infrastructure
(see
.Pa http://dri.freedesktop.org/ )
for supporting video acceleration.
For older chipsets it's used for 3d acceleration only, but newer chipsets
may require
.Nm
for 2d acceleration (XVideo, exa(4)) as well.
.Pp
The
.Nm
drivers provide support for the following chipsets:
.Pp
.Bl -tag -width XsavagedrmXXX -offset indent -compact
.It i915drm
Intel i915, i945, i965, G3x, G4x
.It mach64drm
Mach64 (3D Rage Pro, Rage)
.It mgadrm
Matrox G[24]00, G[45]50
.It r128drm
ATI Rage 128
.It radeondrm
ATI Radeon
.It savagedrm
S3 Savage
.It sisdrm
SiS
.It tdfxdrm
3dfx (Voodoo)
.\".It viadrm
.\"VIA
.El
.Pp
To make use of the driver:
.Pp
.Bl -bullet -compact
.It
The kernel must include
.Xr agp 4
.It
.Xr Xorg 1 ,
MesaLib and the video driver to be used must be compiled with DRI support
.It
DRI must be enabled in the
.Xr xorg.conf 5
configuration file:
.Bd -literal
Section "DRI"
        Group "wheel"
        Mode 0660
EndSection
.Ed
.El
.Pp
In order to use two graphics cards (an on-board and another
AGP/PCI/PCIe card) with DRI, a
.Pa /dev/dri/card1
link to
.Pa /dev/dri/card0
has to be created using
.Xr devfsctl 8 .
.Pp
If
.Xr Xorg 1
acceleration fails to initialize with a
.Dq contigmalloc_map: failed size...
error in dmesg, the reserve of memory for DMA ran out early and should
be increased to a sufficiently high value by setting the
.Va vm.dma_reserved
loader tunable.
A read only
.Xr sysctl 8
variable of the same name is provided for obtaining its current value.
.Pp
Debugging output can be enabled and disabled by setting the
.Xr sysctl 8
node
.Ar hw.dri.0.debug .
.Sh SEE ALSO
.Xr Xorg 1 ,
.Xr agp 4 ,
.\".Xr exa 4 ,
.Xr xorg.conf 5
.Sh HISTORY
DRM was first available for Linux.
Subsequently Eric Anholt ported the DRM kernel modules to
.Fx .
.Sh CAVEATS
Disable AIGLX if necessary
.Pq Pa xorg.conf :
.Bd -literal -offset indent
Section "ServerFlags"
        Option  "AIGLX" "off"
EndSection

Section "Extensions"
        Option "Composite" "Disable"
EndSection
.Ed
.Pp
.Cd options DRM_DEBUG
can slow DRI down a lot, disable it once
.Nm
works.