modesetting - video driver for framebuffer device
modesetting is an Xorg driver for KMS devices. This driver
supports TrueColor visuals at framebuffer depths of 15, 16, 24, and 30.
RandR 1.2 is supported for multi-head configurations. Acceleration is
available through glamor for devices supporting at least OpenGL ES 2.0 or
OpenGL 2.1. If glamor is not enabled, a shadow framebuffer is configured
based on the KMS drivers' preference (unless the framebuffer is 24 bits per
pixel, in which case the shadow framebuffer is always used).
The modesetting driver supports all hardware where a KMS
driver is available. modesetting uses the Linux DRM KMS ioctls and dumb
Please refer to xorg.conf(5) for general configuration details.
This section only covers configuration details specific to this driver.
For this driver it is not required to specify modes in the screen
section of the config file. The modesetting driver can pick up the
currently used video mode from the kernel driver and will use it if there
are no video modes configured.
For PCI boards you might have to add a BusID line to the Device
section. See above for a sample line.
The following driver Options are supported:
- Selects software cursor. The default is off.
- The framebuffer device to use. Default: /dev/dri/card0.
- Enable or disable use of the shadow framebuffer layer. Default: on.
- Double-buffer shadow updates. When enabled, the driver will keep two
copies of the shadow framebuffer. When the shadow framebuffer is flushed,
the old and new versions of the shadow are compared, and only tiles that
have actually changed are uploaded to the device. This is an optimization
for server-class GPUs with a remote display function (typically VNC),
where remote updates are triggered by any framebuffer write, so minimizing
the amount of data uploaded is crucial. This defaults to enabled for
ASPEED and Matrox G200 devices, and disabled otherwise.
- One of "glamor" or "none". Default: glamor.
- Enable DRI3 page flipping. The default is on.
- Enables support for enabling variable refresh on the Screen's CRTCs when
an suitable application is flipping via the Present extension.
The default is off.
- Use async flips for secondary video outputs on multi-display setups. If a
screen has multiple displays attached and DRI3 page flipping is used, then
only one of the displays will have its page flip synchronized to vblank
for tear-free presentation. This is the display that is used for
presentation timing and timestamping, usually the one covering the biggest
pixel area of the screen. All other displays ("Secondaries")
will not synchronize their flips. This may cause some tearing on these
displays, but it prevents a permanent or periodic slowdown or irritating
judder of animations if not all video outputs are running synchronized
with each other and with the same refresh rate. There is no perfect
solution apart from perfectly synchronized outputs, but this option may
give preferrable results if the displays in a multi-display setup mirror
or clone each other. The default is off.
- Specify the RandR output(s) to use with zaphod mode for a particular
driver instance. If you use this option you must use this option for all
instances of the driver.
For example: Option "ZaphodHeads" "LVDS,VGA-0"
will assign xrandr outputs LVDS and VGA-0 to this instance of the
- Enable or disable use of the GAMMA_LUT property, when available. When
enabled, this option allows the driver to use gamma ramps with more
entries, if supported by the kernel. By default, GAMMA_LUT will be used
for kms drivers which are known to be safe for use of GAMMA_LUT.
Xorg(1), xorg.conf(5), Xserver(1), X(7)
Authors include: Dave Airlie