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vga - VGA controller device


bind #v /dev



The VGA device allows configuration of a graphics controller on a PC (and any other platform with VGA devices). Vgactl allows control over higher-level settings such as display height, width, depth, controller and hardware-cursor type. Along with the I/O-port registers provided by arch(3), it is used to implement configuration and setup of VGA controller cards.

Writing strings to vgactl configures the VGA device. The following are valid commands.

size XxYxZ chan
Set the size of the screen image to be X pixels wide and Y pixels high. Each pixel is Z bits as specified by chan, whose format is described in image(6).
actualsize XxY
Set the physical size of the display to be X pixels wide by Y pixels high. This message is optional; it is used to implement panning and to accommodate displays that require the in-memory screen image to have certain alignment properties. For example, a 1400x1050 screen with a 1408x1050 in-memory image will use size 1408x1050 but actualsize 1400x1050.
panning mode
Depending on whether mode is on or off, enable or disable panning in a virtual screen. If panning is on and the screen's size is larger than its actualsize, the displayed portion of the screen will pan to follow the mouse. Setting the panning mode after the first attach of the #i driver has no effect.
type ctlr
Set the type of VGA controller being used. Ctlr is one of ark200pv, clgd542x, clgd546x, ct65545, cyber938x, hiqvideo, mach64xx, mga2164w, neomagic, s3, and t2r4.

Note that this list does not indicate the full set of VGA chips supported. For example, s3 includes the 86C801/5, 86C928, Vision864, and Vision964. It is the job of a user-level program to recognise which particular chip is being used and to initialize it appropriately.
hwgc gc
Set the type of hardware graphics cursor being used. Gc is one of ark200pvhwgc, bt485hwgc, clgd542xhwgc, clgd546xhwgc, ct65545hwgc, cyber938xhwgc, hiqvideohwgc, mach64xxhwgc, mga2164whwgc, neomagichwgc, rgb524hwgc, s3hwgc, t2r4hwgc, tvp3020hwgc, and tvp3026hwgc. A value of off disables the cursor. There is no software cursor.
palettedepth d
Set the number of bits of precision used by the VGA palette to d, which must be either 6 or 8.
Blank the screen. This consists of setting the hardware color map to all black as well as, on some controllers, setting the VGA hsync and vsync signals so as to turn off VESA DPMS-compliant monitors. The screen also blanks after 30 minutes of inactivity. The screen can be unblanked by moving the mouse.
blanktime minutes
Set the timeout before the screen blanks; the default is 30 minutes. If minutes is zero, blanking is disabled.
hwaccel mode
Depending on whether mode is on or off, enable or disable whether hardware acceleration (currently for rectangle filling and moving) used by the graphics engine. The default setting is on.
hwblank mode
Depending on whether mode is on or off, enable or disable the use of DPMS blanking (see blank above).
linear size align
Use a linear screen aperture of size size aligned on an align-byte boundary.
Initialize the graphics hardware. This must be sent after setting the type.

Reading vgactl returns the current settings, one per line.

Some VGA cards support overlay graphics. Writing strings to vgaovlctl configures such cards. The following are valid overlay control commands:

opens the overlay device.
configure w h format
allocates resources inside the driver to support an overlay area of width w and height h pixels. Currently, the only supported format is YUYV packed. In YUYV two pixels are encoded by their separate Y values and their combined U and V values. The size of the two pixels is 32 bits.
enable x y w h
enables drawing data on the display through the overlay mode. The data is drawn at position x,y and has a width and height of w,h respectively.
terminates overlay control.

Overlay data can be written to vgaovl.


The following disables hardware acceleration.

echo hwaccel off > /dev/vgactl






The hardware graphics cursor on the et4000 does not work in 2x8-bit mode.

VGA(3 ) Rev:  Tue Mar 31 02:42:38 GMT 2015