3 vga \- VGA controller device
14 The VGA device allows configuration of a graphics controller
17 allows control over higher-level settings such as display height, width, depth,
18 controller and hardware-cursor type.
19 Along with the I/O-port registers
22 it is used to implement configuration and setup of VGA controller cards.
23 This is usually performed by
27 provides read-only access to the low 640kB of memory,
28 where the VGA and other BIOS ROMs are located.
32 configures the VGA device.
33 The following are valid commands.
35 .BI size " X" x Y x "Z chan"
36 Set the size of the screen image to be
46 whose format is described in
49 .BI actualsize " X" x Y
50 Set the physical size of the display to be
55 This message is optional;
56 it is used to implement panning and to accommodate
57 displays that require the in-memory screen image
58 to have certain alignment properties.
59 For example, a 1400x1050 screen with a 1408x1050 in-memory image
63 .BR "actualsize 1400x1050" .
72 enable or disable panning in a virtual screen.
73 If panning is on and the screen's
77 the displayed portion of the screen will pan to follow the mouse.
78 Setting the panning mode after the first attach of the
83 Set the type of VGA controller being used.
108 Note that this list does not indicate the full set of VGA chips
109 supported. For example,
111 includes the 86C801/5, 86C928, Vision864, and Vision964.
114 to recognize which particular chip is being used and to initialize it
118 Set the type of hardware graphics cursor being used.
150 .BI palettedepth " d"
151 Set the number of bits of precision used by the
166 enable or disable whether hardware acceleration
167 (currently for rectangle filling and moving)
168 used by the graphics engine.
169 The default setting is
172 .BI softscreen " mode"
179 enable or disable shadow framebuffer to reduce
180 slow bus reads. Enabling
182 disables hardware acceleration. The default setting is
195 enable or disable the use of DPMS blanking
199 .BI linear " size align"
200 Use a linear screen aperture of size
207 Initialize the graphics hardware.
208 This must be sent after setting the
213 returns the current settings, one per line.
215 Some VGA cards support overlay graphics.
218 configures such cards.
219 The following are valid overlay control commands:
222 opens the overlay device.
224 .BI configure " w h format"
225 allocates resources inside the driver to support an overlay area
230 pixels. Currently, the only supported
237 two pixels are encoded by their separate Y values
238 and their combined U and V values.
239 The size of the two pixels is 32 bits.
241 .BI enable " x y w h"
242 enables drawing data on the display through the overlay mode. The data
245 and has a width and height of
250 terminates overlay control.
252 Overlay data can be written to
255 The following disables hardware acceleration.
258 echo hwaccel off > /dev/vgactl
261 .B /sys/src/9/pc/devvga.c
266 The hardware graphics cursor on the
268 does not work in 2x8-bit mode.