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
- 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.
- drawinit
- 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:
- 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.