VGA(3)                                                     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 mem-
          ory, 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).

          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 dis-
               able 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

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     VGA(3)                                                     VGA(3)

               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.

          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 hard-
               ware color map to all black as well as, on some con-
               trollers, 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 dis-
               abled.

          hwaccel mode
               Depending on whether mode is on or off, enable or dis-
               able whether hardware acceleration (currently for rect-
               angle 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 dis-
               able shadow framebuffer to reduce slow bus reads.
               Enabling softscreen disables hardware acceleration. The
               default setting is off except for the vesa driver.

          hwblank mode
               Depending on whether mode is on or off, enable or dis-
               able the use of DPMS blanking (see blank above).

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     VGA(3)                                                     VGA(3)

          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.  Cur-
               rently, 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.

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