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NAME

drm — Direct Rendering Manager (DRI kernel support)

DESCRIPTION

The Direct Rendering Manager is part of the Direct Rendering Infrastructure (see http://dri.freedesktop.org/) for supporting video acceleration.

The drm drivers provide support for the following chipsets:

In most cases Xorg(1) will take care of loading the appropriate modules and it is not necessary to modify loader.conf(5) or the kernel configuration to enable drm support.

Newer versions of Xorg(1), like the one from dports(7), do a pretty good job of figuring out the right configuration on their own, so having no xorg.conf(5) file at all is usually the best advice. If for some reason an xorg.conf(5) is preferred, DRI must be enabled:

Section "DRI"
        Group "video"
        Mode 0660
EndSection

With KMS, DRI is always enabled since the drm is always required.

To access /dev/dri/cardN devices user must be a member of the video group. Users can be added to the video group with pw(8) groupmod option.

If Xorg(1) acceleration fails to initialize with a “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 vm.dma_reserved loader tunable. A read only sysctl(8) variable of the same name is provided for obtaining its current value.

LOADER TUNABLES

Tunables can be set at the loader(8) prompt before booting the kernel or stored in loader.conf(5).

drm.debug

Enable internal verbose debug messages, might slow down the machine. Debug categories are enabled by setting their bits:

0x001

CORE - generic drm code

0x002

DRIVER - vendor specific parts of the driver

0x004

KMS - modesetting troubleshoot

0x008

PRIME (no prime support)

0x010

ATOMIC - atomic code used by i915

0x100

PID - include pid number (useful in certain scenarios)

0x200

FIOCTL - failed ioctls

0x400

IOCTL - very spammy ioctl prints

0x800

VBLANK - very spammy vblank prints

drm.edid_firmware

Load external EDID binary monitor data from a firmware module. Useful if the monitor is not sending an appropriate EDID block, if there is no video on the connected monitor or if there is a need to enforce custom video modes. Optionally, the connector name can be specified before the firmware name followed by a colon. For example:

drm.edid_firmware="DVI-D-1:edidfw_repaired"

Notes: drm and Xorg(1) use different naming conventions for connector names. This tunable only applies for KMS drivers.

drm.video.<connector>

Can be used to set framebuffer parameters for drm(4) connector. Mode specifier format:

<xres>x<yres>[M][R][-<bpp>][@<refresh>][i][m][eDd]

<xres>

X resolution, e.g. 1920

<yres>

Y resolution, e.g. 1080

M

calculate timings using VESA CVT instead of table lookups

R

reduced blanking on digital monitors

<bpp>

color depth

<refresh>

refresh rate

i

calculate timings for interlaced mode

m

margins used in calculations

e

force enable output

D

same as e option, but force digital output on HDMI/DVI

d

force disable output

SYSCTL VARIABLES

A number of sysctl(8) variables are available:

hw.dri.debug

If set, enables debugging output.

hw.dri.vblank_offdelay

Specifies the delay (in milliseconds) until the vblank interrupt is disabled again when it's no longer needed. (0 = never disable, negative value = disable immediately)

hw.dri.%d.busid

Indicates the location of the device on the PCI bus. The format is:

[0000-ffff]:[00-ff]:[00-1f].[0-7]

hw.dri.%d.modesetting

Indicates if kernel mode setting (DRIVER_MODESET feature) is set in the device driver.

SEE ALSO

Xorg(1), i915kms(4), radeonkms(4), xorg.conf(5)

HISTORY

DRM was first available for Linux. Subsequently Eric Anholt ported the DRM kernel modules to FreeBSD.

CAVEATS

Disable AIGLX if necessary (xorg.conf):

Section "ServerFlags"
        Option  "AIGLX" "off"
EndSection

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