LibertyBSD_xenocara/xenocara/driver/xf86-video-apm

Information for Alliance Promotion chipset users
Loic Grenie ( ), Henrik
Harmsen ( )
6 March 2000
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Table of Contents


1. Support chipsets
2. Acceleration
3. DGA
4. Video
5. Shadow framebuffer
6. Configuration
7. glide2x
8. Questions


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1. Support chipsets

The apm driver in the SVGA server is for Alliance Promotion graphics
chipsets. The following chipsets are supported:


o 6422

Old chipset. The driver is still very unstable and has computer
crashes. You should use XFree86 3.3.x for this chipset.


o AT24

As found in Diamond Stealth Video 2500. Quite similar to AT3D.

o AT25, AT3D

AT3D is found in Hercules Stingray 128/3D. Most other Voodoo Rush
based cards use the AT25 which is identical except it doesn't have
the 3D stuff in it.


2. Acceleration

The apm driver uses the XAA in the SVGA server. It has support for the
following acceleration:


o Bitblts (rectangle copy operation)

o Lines (solid, single pixel)

o Filled rectangles

o CPU->Screen image transfers.

o CPU->Screen colour expansion (text accel).

o Screen->Screen colour expansion (cached text accel).

o Mono 8x8 pattern fill. Not for 6422.

o Colour 8x8 pattern fill (in 8bpp). Not for 6422.

o Hardware cursor.

o Pixmap caching.

All in 8, 16 and 32 bpp modes. In 24bpp mode only Bitblts and Filled
rectangles is supported. Also VESA DPMS power save mode is fully
supported with "standby", "suspend" and "off" modes (set with with the
"xset dpms" command).


3. DGA

Full DGA 2.0 support with framebuffer access and drawing acceleration.


4. Video

It has limited hardware support for video decoding on the AT24 and
AT25/3D. It can also display an image in YUV colours inside the
desktop. There are some more exotic formats such as YUV 4.1.1, YUV
4.0.0 and RGB 8,16.32bpp.


5. Shadow framebuffer

There is a mode, called shadow framebuffer, where the graphics are
used to display the images. All rendering is done in memory in a so-
called shadow framebuffer. This mode is useful if you need lots of
reading in the video memory and to use it you will have to put

Option "ShadowFB"



in your xorg.conf file.


6. Configuration

You can turn off hardware cursor by inserting the following line in
the Device section of the xorg.conf file:

Option "SWcursor"



Or turn off hardware acceleration:

Option "noaccel"



Or turn off MMIO


Option "nolinear"



Do not specify either the amount of video RAM or which chipset in the
config file. It is better to let the driver probe for this. Also don't
put any "clocks" line in the device section since these chips have a
fully programmable clock that can almost take any modeline you throw
at it. It might though fail at some specific clock values but in that
case you should just try a slightly different clock and it should
work.


7. glide2x

There is support for the XF86Rush extension for use with the glide2x
library.


8. Questions

Any questions regarding this driver should be sent to Loic Grenie. It
should be possible to add support for the 3210 chipset if someone
needs it.