term% cat index.txt VGA(3) Library Functions Manual 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 memory, 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 pix‐
els high. Each pixel is Z bits as specified by chan, whose for‐
mat 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 pan‐
ning 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, 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, Vi‐
sion864, and Vision964. It is the job of vga(8) to recognize
which particular chip is being used and to initialize it appro‐
priately.
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 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-compli‐
ant monitors. The screen also blanks after 30 minutes of inac‐
tivity. The screen can be unblanked by moving the mouse.
blanktime minutes
Set the timeout before the screen blanks; the default is 30 min‐
utes. 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.
softscreen mode
Depending on whether mode is on or off, enable or disable shadow
framebuffer to reduce slow bus reads. Enabling softscreen dis‐
ables hardware acceleration. The default setting is off except
for the vesa driver.
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.
drawinit
Initialize the graphics hardware. This must be sent after set‐
ting 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 com‐
mands:
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. 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.
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.
VGA(3)