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 performed 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 pixels
high. Each pixel is Z bits as specified by chan, whose format
is described in image(6).
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.
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.
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, Vision864,
and Vision964. It is the job of vga(8) to recognize which particular
chip is being used and to initialize it appropriately.
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.
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.
Set the timeout before the screen blanks; the default is 30 minutes.
If minutes is zero, blanking is disabled.
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.
linear size align
Depending on whether mode is on or off, enable or disable the
use of DPMS blanking (see blank above).
Use a linear screen aperture of size size aligned on an align–byte
Reading vgactl returns the current settings, one per line.
Initialize the graphics hardware. This must be sent after setting
Some VGA cards support overlay graphics. Writing strings to vgaovlctl
configures such cards. The following are valid overlay control
configure w h format
opens the overlay device.
enable x y w h
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.
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
Overlay data can be written to vgaovl.
terminates overlay control.