VGA(3) VGA(3)
NAME
vga - VGA controller device
SYNOPSIS
bind #v /dev
/dev/vgabios
/dev/vgactl
/dev/vgaovl
/dev/vgaovlctl
DESCRIPTION
The VGA device allows configuration of a graphics controller
on a PC. 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. This is usually per-
formed by vga(8).
Vgabios provides read-only access to the low 640kB of mem-
ory, where the VGA and other BIOS ROMs are located.
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 dis-
able 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
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VGA(3) VGA(3)
of ark200pv, clgd542x, clgd546x, ct65545, cyber938x,
hiqvideo, mach64xx, mga2164w, neomagic, nvidia, 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 vga(8) to recognize 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, nvidiahwgc,
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
Blank the screen. This consists of setting the hard-
ware color map to all black as well as, on some con-
trollers, 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 dis-
abled.
hwaccel mode
Depending on whether mode is on or off, enable or dis-
able whether hardware acceleration (currently for rect-
angle 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 dis-
able 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.
drawinit
Initialize the graphics hardware. This must be sent
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VGA(3) VGA(3)
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:
openctl
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. Cur-
rently, 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.
closectl
terminates overlay control.
Overlay data can be written to vgaovl.
EXAMPLES
The following disables hardware acceleration.
echo hwaccel off > /dev/vgactl
SOURCE
/sys/src/9/pc/devvga.c
SEE ALSO
arch(3), vga(8)
BUGS
The hardware graphics cursor on the et4000 does not work in
2x8-bit mode.
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