.TH VGA 3 
.SH NAME
vga \- VGA controller device
.SH SYNOPSIS
.nf
.B bind #v /dev

.B /dev/vgactl
.fi
.SH DESCRIPTION
The VGA device allows configuration of a graphics controller
on a PC.
.B 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
.IR arch (3),
it is used to implement configuration and setup of VGA controller cards.
This is usually performed by
.IR vga (8).
.PP
Writing strings to 
.B vgactl
configures the VGA device.
The following are valid commands.
.TP
.BI size " X" x Y x "Z chan"
Set the size of the screen image to be
.I X 
pixels wide
and
.I Y 
pixels high.
Each pixel is 
.I Z 
bits as specified by 
.IR chan ,
whose format is described in
.IR image (6).
.TP
.BI actualsize " X" x Y
Set the physical size of the display to be
.I X
pixels wide by
.I Y 
pixels high.
This message is optional;
it is used 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 
.B "size 1408x1050
but
.BR "actualsize 1400x1050" .
.TP
.BI tilt " value"
Set the tilt of the screen,
altering the screen's orientation.
The
.I value
can be one of:
.BR none ,
.BR left ,
.B inverted
and
.BR right .
.TP
.BI type " ctlr"
Set the type of VGA controller being used.
.I Ctlr
is one of 
.BR 3dfx ,
.BR ark200pv ,
.BR clgd542x ,
.BR clgd546x ,
.BR ct65545 ,
.BR cyber938x ,
.BR et4000 ,
.BR geode ,
.BR hiqvideo ,
.BR i81x ,
.BR igfx ,
.BR mach64xx ,
.BR mga2164w ,
.BR mga4xx ,
.BR neomagic ,
.BR nvidia ,
.BR radeon ,
.BR s3 ,
.BR t2r4
and
.BR vmware .
.IP
Note that this list does not indicate the full set of VGA chips
supported. For example,
.B s3
includes the 86C801/5, 86C928, Vision864, and Vision964.
It is the job of
.IR vga (8)
to recognize which particular chip is being used and to initialize it
appropriately.
.TP
.BI hwgc " gc"
Set the type of hardware graphics cursor being used.
.I Gc
is one of
.BR soft ,
.BR 3dfxhwgc ,
.BR ark200pvhwgc ,
.BR bt485hwgc ,
.BR clgd542xhwgc ,
.BR clgd546xhwgc ,
.BR ct65545hwgc ,
.BR cyber938xhwgc ,
.BR et4000hwgc ,
.BR geodehwgc ,
.BR hiqvideohwgc ,
.BR i81xhwgc ,
.BR igfxhwgc ,
.BR mga2164whwgc ,
.BR mach64xxhwgc ,
.BR neomagichwgc ,
.BR nvidiahwgc ,
.BR radeonhwgc ,
.BR rgb524hwgc ,
.BR s3hwgc ,
.BR t2r4hwgc ,
.BR tvp3020hwgc ,
.BR tvp3026hwgc
and
.BR vmwarehwgc .
A value of
.B off
disables the cursor.
.TP
.BI palettedepth " d"
Set the number of bits of precision used by the 
VGA palette to 
.IR d ,
which must be either 
.B 6
or
.BR 8 .
.TP
.BI hwaccel " mode"
Depending on whether
.I mode
is 
.B on
or
.BR off ,
enable or disable whether hardware acceleration
(currently for rectangle filling and moving)
used by the graphics engine.
The default setting is
.BR on .
.TP
.BI softscreen " mode"
Depending on whether
.I mode
is 
.B on
or
.BR off ,
enable or disable shadow framebuffer to reduce
slow bus reads. Enabling
.BI softscreen
disables hardware acceleration. The default setting is
.BR off
except for the
.BR vesa
driver. 
.TP
.BI hwblank " mode"
Depending on whether
.I mode
is
.B on
or
.BR off ,
enable or disable the use of DPMS blanking
(see
.IR mouse (3)).
.TP
.BI linear " size align"
Use a linear screen aperture of size
.I size
aligned on an
.IR align -byte
boundary.
.TP
.B drawinit
Initialize the graphics hardware.
This must be sent after setting the
.BR type .
.PP
Reading
.B vgactl
returns the current settings, one per line.
.SH EXAMPLES
The following disables hardware acceleration.
.IP
.EX
echo hwaccel off > /dev/vgactl
.EE
.SH SOURCE
.B /sys/src/9/pc/devvga.c
.SH SEE ALSO
.IR arch (3),
.IR vga (8)
.SH BUGS
The hardware graphics cursor on the
.B et4000
does not work in 2x8-bit mode.