269 lines
4.9 KiB
Plaintext
269 lines
4.9 KiB
Plaintext
.TH VGA 3
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.SH NAME
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vga \- VGA controller device
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.SH SYNOPSIS
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.nf
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.B bind #v /dev
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.B /dev/vgabios
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.B /dev/vgactl
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.B /dev/vgaovl
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.B /dev/vgaovlctl
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.fi
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.SH DESCRIPTION
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The VGA device allows configuration of a graphics controller
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on a PC.
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.B Vgactl
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allows control over higher-level settings such as display height, width, depth,
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controller and hardware-cursor type.
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Along with the I/O-port registers
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provided by
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.IR arch (3),
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it is used to implement configuration and setup of VGA controller cards.
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This is usually performed by
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.IR vga (8).
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.PP
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.B Vgabios
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provides read-only access to the low 640kB of memory,
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where the VGA and other BIOS ROMs are located.
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.PP
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Writing strings to
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.B vgactl
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configures the VGA device.
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The following are valid commands.
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.TP
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.BI size " X" x Y x "Z chan"
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Set the size of the screen image to be
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.I X
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pixels wide
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and
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.I Y
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pixels high.
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Each pixel is
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.I Z
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bits as specified by
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.IR chan ,
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whose format is described in
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.IR image (6).
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.TP
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.BI actualsize " X" x Y
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Set the physical size of the display to be
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.I X
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pixels wide by
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.I Y
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pixels high.
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This message is optional;
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it is used to implement panning and to accommodate
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displays that require the in-memory screen image
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to have certain alignment properties.
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For example, a 1400x1050 screen with a 1408x1050 in-memory image
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will use
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.B "size 1408x1050
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but
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.BR "actualsize 1400x1050" .
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.TP
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.BI panning " mode"
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Depending on whether
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.I mode
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is
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.B on
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or
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.BR off ,
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enable or disable panning in a virtual screen.
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If panning is on and the screen's
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.B size
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is larger than its
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.BR actualsize ,
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the displayed portion of the screen will pan to follow the mouse.
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Setting the panning mode after the first attach of the
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.B #i
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driver has no effect.
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.TP
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.BI type " ctlr"
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Set the type of VGA controller being used.
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.I Ctlr
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is one of
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.BR 3dfx ,
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.BR ark200pv ,
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.BR clgd542x ,
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.BR clgd546x ,
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.BR ct65545 ,
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.BR cyber938x ,
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.BR et4000 ,
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.BR geode ,
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.BR hiqvideo ,
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.BR i81x ,
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.BR igfx ,
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.BR mach64xx ,
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.BR mga2164w ,
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.BR mga4xx ,
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.BR neomagic ,
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.BR nvidia ,
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.BR radeon ,
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.BR s3 ,
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.BR t2r4
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and
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.BR vmware .
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.IP
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Note that this list does not indicate the full set of VGA chips
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supported. For example,
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.B s3
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includes the 86C801/5, 86C928, Vision864, and Vision964.
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It is the job of
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.IR vga (8)
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to recognize which particular chip is being used and to initialize it
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appropriately.
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.TP
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.BI hwgc " gc"
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Set the type of hardware graphics cursor being used.
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.I Gc
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is one of
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.BR soft ,
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.BR 3dfxhwgc ,
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.BR ark200pvhwgc ,
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.BR bt485hwgc ,
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.BR clgd542xhwgc ,
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.BR clgd546xhwgc ,
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.BR ct65545hwgc ,
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.BR cyber938xhwgc ,
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.BR et4000hwgc ,
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.BR geodehwgc ,
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.BR hiqvideohwgc ,
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.BR i81xhwgc ,
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.BR igfxhwgc ,
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.BR mga2164whwgc ,
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.BR mach64xxhwgc ,
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.BR neomagichwgc ,
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.BR nvidiahwgc ,
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.BR radeonhwgc ,
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.BR rgb524hwgc ,
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.BR s3hwgc ,
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.BR t2r4hwgc ,
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.BR tvp3020hwgc ,
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.BR tvp3026hwgc
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and
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.BR vmwarehwgc .
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A value of
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.B off
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disables the cursor.
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.TP
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.BI palettedepth " d"
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Set the number of bits of precision used by the
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VGA palette to
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.IR d ,
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which must be either
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.B 6
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or
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.BR 8 .
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.TP
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.BI hwaccel " mode"
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Depending on whether
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.I mode
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is
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.B on
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or
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.BR off ,
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enable or disable whether hardware acceleration
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(currently for rectangle filling and moving)
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used by the graphics engine.
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The default setting is
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.BR on .
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.TP
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.BI softscreen " mode"
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Depending on whether
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.I mode
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is
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.B on
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or
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.BR off ,
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enable or disable shadow framebuffer to reduce
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slow bus reads. Enabling
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.BI softscreen
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disables hardware acceleration. The default setting is
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.BR off
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except for the
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.BR vesa
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driver.
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.TP
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.BI hwblank " mode"
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Depending on whether
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.I mode
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is
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.B on
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or
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.BR off ,
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enable or disable the use of DPMS blanking
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(see
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.IR mouse (3)).
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.TP
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.BI linear " size align"
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Use a linear screen aperture of size
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.I size
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aligned on an
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.IR align -byte
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boundary.
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.TP
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.B drawinit
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Initialize the graphics hardware.
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This must be sent after setting the
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.BR type .
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.PP
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Reading
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.B vgactl
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returns the current settings, one per line.
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.PP
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Some VGA cards support overlay graphics.
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Writing strings to
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.B vgaovlctl
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configures such cards.
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The following are valid overlay control commands:
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.TP
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.BI openctl
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opens the overlay device.
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.TP
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.BI configure " w h format"
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allocates resources inside the driver to support an overlay area
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of width
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.I w
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and height
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.I h
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pixels. Currently, the only supported
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.I format
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is
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.B YUYV
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packed.
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In
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.B YUYV
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two pixels are encoded by their separate Y values
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and their combined U and V values.
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The size of the two pixels is 32 bits.
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.TP
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.BI enable " x y w h"
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enables drawing data on the display through the overlay mode. The data
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is drawn at position
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.IR x , y
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and has a width and height of
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.IR w , h
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respectively.
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.TP
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.BI closectl
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terminates overlay control.
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.PP
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Overlay data can be written to
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.BR vgaovl .
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.SH EXAMPLES
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The following disables hardware acceleration.
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.IP
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.EX
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echo hwaccel off > /dev/vgactl
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.EE
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.SH SOURCE
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.B /sys/src/9/pc/devvga.c
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.SH SEE ALSO
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.IR arch (3),
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.IR vga (8)
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.SH BUGS
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The hardware graphics cursor on the
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.B et4000
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does not work in 2x8-bit mode.
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