man via (Fichiers spéciaux) - VIA unichrome graphics driver


via - VIA unichrome graphics driver


Section qDeviceq
  Identifier qdevnameq
  Driver qviaq


via is an Xorg driver for VIA chipsets with onboard unichrome graphics.

The via driver supports the VIA CLE266, KM400/KN400 chipsets, including 2D acceleration and the Xv video overlay extensions. Flat panel, TV and VGA outputs are supported.

K8M800/K8N800, PM8X0 and CN400 support is still under development.

Direct rendering 3D is available using experimental drivers in Mesa, Also there is an XvMC client library for hardware MPEG1 / MPEG2 decoding acceleration available on the CLE266 and K8M/N800 chipsets that uses the Direct Rendering Infrastructure, DRI. The XvMC client library implements a nonstandard qVLDq extension to the XvMC standard. The current Direct Rendering Manager Linux kernel module is available at


Please refer to xorg.conf(5) for general configuration details. This section only covers configuration details specific to this driver.

The following driver options are supported

Option qNoAccelq qbooleanq
Disable or enable acceleration. Default: acceleration is enabled.
Option qHWCursorq qbooleanq
Disable or enable use of hardware cursors. The default is enabled.
Option qSWCursorq qbooleanq
Disable or enable the use of a software cursor. The default is disabled.
Option qShadowFBq qbooleanq
Use a shadow frame buffer. This is required when rotating the display, but otherwise defaults to disabled.
Option qVideoRAMq qbooleanq
Override the VideoRAM auto detection. This should never be needed.
Option qRotateq qstringq
Rotate the display either clockwise (qCWq) or counter clockwise (qCCWq). Rotation is only supported unaccelerated.
Option qActiveDeviceq qstringq
Specify the active device combination. Any string containing qCRTq, qLCDq, qTVq should be possible. The default is to use what is detected. The driver is currently unable to use LCD and TV simultaneously, and will favour the LCD.
Option qLCDDualEdgeq qbooleanq
Use dual edge mode to set the LCD.
Option qCenterq qbooleanq
Disable or enable image centering on DVI displays.
Option qPanelSizeq qstringq
Specify the size (width x height) of the LCD panel attached to the system. Sizes 640x480, 800x600, 1024x768, 1280x1024, and 1400x1050 are supported.
Option qTVDotCrawlq qbooleanq
Disable or enable dotcrawl.
Option qTVDeflickerq qintegerq
Specify deflicker setting for TV output. Valid values are 0,1,2 0) No deflicker, 1) 1:1:1 deflicker, 2) 1:2:1 deflicker.
Option qTVTypeq qstringq
Specify TV output format. The driver currently supports qNTSCq and qPALq timings only.
Option qTVOutputq qstringq
Specify which TV output to use. The driver supports qS-Videoq, qCompositeq, qSCq, qRGBq and qYCbCrq outputs. Note that on some EPIA boards the composite video port is shared with audio out and jumper selected.
Option qDisableVQq qbooleanq
Disable or enable the use of VQ. VQ is enabled by default.
Option qDRIXINERAMAq qbooleanq
Set DRI Xinerama mode. Currently unsupported.
Option qEnableAGPDMAq qbooleanq
Enable the AGP DMA functionality in DRM. This requires that DRI is enabled and will force 2D acceleration to use AGP DMA. The XvMC DRI client will also make use of this to consume much less CPU.
Option qNoAGPFor2Dq qbooleanq
With this option on, 2D acceleration will not use AGP DMA even if it is enabled.
Option qVBEModesq qbooleanq
The driver will set modes using BIOS similar to the way the vesa driver does. This is the default behaviour for Unichrome Pro in panel mode, which is otherwise not supported. Use this option only when the driver does not support your particular hardware.

Supported TV Encoders

Unichromes tend to be paired with several different TV Encoders.

VIA Technologies VT1621
Untested as no combination with Unichrome is known or available. Supports the following normal modes: q640x480q and q800x600q. Use q640x480Overq and q800x600Overq for vertical overscan. These modes are made available by the driver and modelines provided in xorg.conf will be ignored.
VIA Technologies VT1622, VT1622A, VT1623
Supports the following modes: q640x480q, q800x600q, q1024x768q, q848x480q, q720x480q (NTSC only) and q720x576q (PAL only). Use q640x480Overq, q800x600Overq, q1024x768Overq, q848x480Overq, q720x480Overq (NTSC) and q720x576Overq (PAL) for vertical overscan. The modes q720x480Noscaleq (NTSC VT1622 only) and q720x576Noscaleq (PAL VT1622 and VT1622a only) provide cleaner TV output (unscaled with only minimal overscan). These modes are made available by the driver and modelines provided in xorg.conf will be ignored.


The driver is not fully 64 bit clean. In particular, 3D acceleration, XvMC and VBEModes do not work properly in 64-bit mode.



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