DragonFly On-Line Manual Pages

DRM(4)                DragonFly Kernel Interfaces Manual                DRM(4)

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:

           Module           Kernel option        Chipset
           i915.ko          i915                 Intel i915, i945, i965, G3x,
                                                 G4x
           radeon.ko        radeon               AMD/ATI Radeon
           amdgpu.ko        n/a                  newer AMD 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), amdgpu(4), i915(4), radeon(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.

DragonFly 6.3-DEVELOPMENT        June 18, 2022       DragonFly 6.3-DEVELOPMENT