s3virge - S3 ViRGE video driver
Section "Device"
 Identifier "devname"
 Driver "s3virge"
  ...
  [ Option "optionname"
  ["optionvalue"]]
EndSection
s3virge is an Xorg driver for S3 based video cards. The driver is fully
  accelerated, and provides support for the following framebuffer depths: 8, 15,
  16, and 24. All visual types are supported for depth 8, and TrueColor visuals
  are supported for the other depths. XVideo hardware up scaling is supported in
  depth 16 and 24 on the DX, GX, GX2, MX, MX+, and Trio3D/2X. Doublescan modes
  are supported and tested in depth 8 and 16 on DX, but disable XVideo.
  Doublescan modes on other chipsets are untested.
The s3virge driver supports PCI and AGP video cards based on the
  following S3 chips:
  - ViRGE
- 86C325
- ViRGE VX
- 86C988
- ViRGE DX
- 86C375
- ViRGE GX
- 86C385
- ViRGE GX2
- 86C357
- ViRGE MX
- 86C260
- ViRGE MX+
- 86C280
- Trio 3D
- 86C365
- Trio 3D/2X
- 86C362, 86C368
Please refer to xorg.conf(5) for general configuration details. This section
  only covers configuration details specific to this driver. All options names
  are case and white space insensitive when parsed by the server, for example,
  "virge vx" and "VIRGEvx" are equivalent.The driver auto-detects the chipset type, but the following
    ChipSet names may optionally be specified in the config file
    ""Device"" section, and will override the
    auto-detection:
"virge", "86c325", "virge
  vx", "86c988", "virge dx", "86c375",
  "virge gx", "86c385", "virge gx2",
  "86c357", "virge mx", "86c260", "virge
  mx+", "86c280", "trio 3d", "86c365",
  "trio 3d/2x", "86c362", "86c368".
The following Cursor Options are supported:
  - Option "HWCursor"
    ["boolean"]
- Enable or disable the HW cursor. Default: on.
- Option "SWCursor"
    ["boolean"]
- Inverse of "HWCursor". Default: off.
    
  
The following display Options are supported:
  - Option "ShadowFB"
    ["boolean"]
- Use shadow framebuffer. Disables HW acceleration. Default: off.
- Option "Rotate" "cw | ccw"
- Rotate the screen CW - clockwise or CCW - counter clockwise. Disables HW
      Acceleration and HW Cursor, uses ShadowFB. Default: no rotation.
- Option "XVideo" ["boolean"]
- Disable XVideo support by using the off option. This changes FIFO settings
      which prevent screen noise for high-res modes. Default: on
    
  
The following video memory Options are supported:
  - Option "slow_edodram"
- Switch the standard ViRGE to 2-cycle edo mode. Try this if you encounter
      pixel corruption on the ViRGE. Using this option will cause a large
      decrease in performance. Default: off.
- Option "fpm_vram"
- Switch the ViRGE/VX to fast page mode vram mode. Default: off.
- Option "slow_dram | fast_dram"
- Change Trio 3D and 3D/2X memory options. Default: Use BIOS defaults.
- Option "early_ras_precharge |
    late_ras_precharge"
- adjust memory parameters. One of these will us the same settings as your
      video card defaults, and using neither in the config file does the same.
      Default: none.
- Option "set_mclk" "integer"
- sets the memory clock, where integer is in kHz, and integer
      <= 100000. Default: probe the memory clock value, and use it at server
      start.
- Option "set_refclk"
    "integer"
- sets the ref clock for ViRGE MX, where integer is in kHz. Default:
      probe the memory clock value, and use it at server start.
    
    
  
The following acceleration and graphics engine Options are
    supported:
  - Option "NoAccel"
- Disable acceleration. Very useful for determining if the driver has
      problems with drawing and acceleration routines. This is the first option
      to try if your server runs but you see graphic corruption on the screen.
      Using it decreases performance, as it uses software emulation for drawing
      operations the video driver can accelerate with hardware. Default:
      acceleration is enabled.
- Option "UseFB"
- There are two framebuffer rendering methods. fb and cfb. Both are
      available in the driver. fb is the newer and default method. To switch
      back to cfb use this option with no, off or other negative parameter.
      Default: on.
- Option "fifo_aggressive | fifo_moderate |
    fifo_conservative"
- alter the settings for the threshold at which the pixel FIFO takes over
      the internal memory bus to refill itself. The smaller this threshold, the
      better the acceleration performance of the card. You may try the fastest
      setting (fifo_aggressive) and move down if you encounter pixel
      corruption. The optimal setting will probably depend on dot-clock and on
      color depth. Note that specifying any of these options will also alter
      other memory settings which may increase performance, so trying
      fifo_conservative will in most cases be a slight benefit (this uses
      the chip defaults). If pixel corruption or transient streaking is observed
      during drawing operations then removing any fifo options is recommended.
      Default: none.
    
  
The following PCI bus Options are supported:
  - Option "pci_burst"
    ["boolean"]
- will enable PCI burst mode. This should work on all but a few broken PCI
      chipsets, and will increase performance. Default: off.
- Option "pci_retry"
    ["boolean"]
- will allow the driver to rely on PCI Retry to program the ViRGE registers.
      pci_burst must be enabled for this to work. This will increase
      performance, especially for small fills/blits, because the driver does not
      have to poll the ViRGE before sending it commands to make sure it is
      ready. It should work on most recent PCI chipsets. Default: off.
The following ViRGE MX LCD Options are supported:
  - Option "lcd_center"
- Option "set_lcdclk"
    "integer"
- allows setting the clock for a ViRGE MX LCD display. integer is in
      Hz. Default: use probed value.
    
  
The following additional Options are supported:
  - Option "ShowCache"
    ["boolean"]
- Enable or disable viewing offscreen cache memory. A development debug
      option. Default: off.
- Option "mx_cr3a_fix"
    ["boolean"]
- Enable or disable a cr3a fix added for ViRGE MX. Default: on.
    
  
Xorg(1), xorg.conf(5), Xserver(1), X(7)
The VideoRam generic driver parameter is presently ignored by the s3virge
  driver. On PPC this is reported to cause problems for 2M cards, because they
  may autodetect as 4M.
For assistance with this driver, or XFree86 in general, check the XFree86 web
  site at http://www.xfree86.org. A FAQ is available on the web site at
  http://www.xfree86.org/FAQ/. If you find a problem with XFree86 or have a
  question not answered in the FAQ please use our bug report form available on
  the web site or send mail to XFree86@XFree86.org. When reporting problems with
  the driver send as much detail as possible, including chipset type, a server
  output log, and operating system specifics.
Kevin Brosius, Matt Grossman, Harald Koenig, Sebastien Marineau, Mark Vojkovich.