<!DOCTYPE linuxdoc PUBLIC "-//XFree86//DTD linuxdoc//EN">

<article>
<title> Information for S3 ViRGE, ViRGE/DX, ViRGE/GX, ViRGE/GX2, 
ViRGE/MX and ViRGE/VX Users
<author>The XFree86 Project Inc.
<date>1 March 1998
<toc>

<sect> Supported hardware
<p>
With release 3.3.2 of XFree86, there are now two servers which support
the ViRGE family of chips. The XF86_S3V server 
is a dedicated server which supports the S3 ViRGE (86C325), the ViRGE/DX 
(86C375), ViRGE/GX (86C385) and the ViRGE/VX (86C988) chips. New with 
this release, the above ViRGE chipsets are also supported in the 
XF86_SVGA server, which includes a new ViRGE driver making use 
of the XAA acceleration architecture and also supports 
ViRGE/GX2 (86C357) and ViRGE/MX (86C260) chips now.
<p>
The following sections describe details of ViRGE support.  Be aware that
there are two servers described.  XF86_S3V is the ViRGE specific server
and was created first.  The new acceleration architecture support is found
in the XF86_SVGA server using the s3_virge driver.  Each has strengths and
weaknesses.

<sect> XF86_S3V server
<p>
The S3V server has some minor fixes since 3.3.1.
You should find that the ViRGE server is stable at all depths.
The server supports 1 and 32 bpp
pixmap formats.
This fixes known problems with xanim and Netscape clients in 
early versions of the S3V server.
It has been tested with ViRGE cards with 2 and 4MB DRAM, ViRGE/DX 4M,
 ViRGE/VX 8M (4M VRAM/4M DRAM), and with a 220MHz ViRGE/VX card with 2MB
VRAM up to 1600x1200 with 8/15/16bpp.
  
NOTE: This driver is pretty new, and not everything might work like you expect
it to. It shouldn't crash your machine, but you may have video artifacts
or missing lines. Please report any and all problems to
<htmlurl name="XFree86@Xfree86.org" url="mailto:XFree86@Xfree86.org">
using the appropriate bug report sheet. 

<sect1>Features:
<p>

<itemize>
<item>Basic support for S3 ViRGE, ViRGE/DX, ViRGE/GX and ViRGE/VX video
  adapters
<item>uses linear frame buffer
<item>it should be possible to reach resolutions up to the maximum supported
 by your video card memory.  (eg. 1600x1200 at 8 and 16bpp, 1280x1024 at
 24/32 bpp for a 4 Meg. card)
<item>it should be possible to use pixel depths of 8, 15, 16, 24, and 32 bits
  per pixel.
<item>32 bpp is implemented as translation to 24 bpp
</itemize>
		       
<sect1>Known limitations
<p>

<itemize>
<item>No support for external RAMDACs on the ViRGE/VX.
<item>No support for VLB cards.
<item>No support for doublescan modes.
<item>The driver only works with linear addressing.
<item>For 24/32 bpp some simple dashed line acceleration is implemented, but
sloped dash/double dash are drawn as solid lines.
</itemize>

<sect1>Future Features (in order from highest to lowest priority)
<p>

<itemize>
<item>there is a good chance that the SVGA ViRGE driver will replace XF86_S3V
in future releases
<item>some more hardware acceleration
<item>3d acceleration (once we work out how that's done)
<item>more chipsets and RAMDACs
</itemize>

<sect1>Configuration:
<p>

The server auto-detects RAM size, RAMDAC and ClockChip. Do not bother putting 
these in your "Device" section. 
The "nolinear" option is unsupported.

<sect2>Cursor:
<p>

<itemize>
<item>The default is hardware cursor, no option is needed.
<item>"sw_cursor" switches to software cursor.
</itemize>

<sect> XF86_SVGA server
<p>
The XF86_SVGA ViRGE driver supports all current flavors of the S3 ViRGE
chipset. 
It uses the XAA acceleration architecture for acceleration, and allows
color depths of 8, 15, 16, 24 and 32 bpp. It has been tested on several 2MB
and 4MB ViRGE cards, a 4MB ViRGE/DX card and a ViRGE/VX card. Resolutions 
of up to 1600x1200 have been achieved. This is an early release of this
driver, and not everything may work as expected. Please report any problems 
to <htmlurl name="XFree86@Xfree86.org" url="mailto:XFree86@Xfree86.org">
using the appropriate bug report sheet. 

<sect1>Features
<p>

<itemize>
<item>Supports PCI hardware, ViRGE, ViRGE/DX, ViRGE/GX, ViRGE/GX2, ViRGE/MX 
and ViRGE/VX.
<item>Supports 8bpp, 15/16bpp, 24bpp and 32bpp.
<item>VT switching seems to work well, no corruption reported 
at all color depths. 
<item>Acceleration is pretty complete: Screen-to-screen copy, solid rectangle 
fills, CPU-to-screen color expansion, 8x8 pattern mono and color fills. 
Currently, the color expansion appears to be substantially faster than 
the accel server due to the optimized XAA routines.
<item>Acceleration at 32bpp is limited: only ScreenToScreen bitblit and solid 
rectangles are supported. The ViRGE itself has no support for 32bpp 
acceleration, so the graphics engine is used in 16bpp mode. 
<item>All modes include support for a hardware cursor.
</itemize>

<sect1>Known limitations
<p>

<itemize>
<item>No support for external RAMDACs on the ViRGE/VX.
<item>No support for VLB cards.
<item>No support for doublescan modes.
<item>The driver only works with linear addressing.
<item>Lines and polygons are not accelerated yet (but XAA still provides some
acceleration in this respect).
</itemize>

<sect1>Configuration
<p>

The ViRGE SVGA driver supports a large number of XF86Config options, which can 
be used to tune PCI behavior and improve performance.

Memory options:
<itemize>
<item>"slow_edodram" will switch the 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. 
<item>"early_ras_precharge" and "late_ras_precharge" will modify the memory 
timings, and may fix pixel corruption on some cards. The default behavior 
is set by the BIOS, and is normally "late_ras_precharge".
<item>"set_mclk value" sets the video memory clock rate to 'value' (in MHz).
The performance of the card is directly proportional to the memory
clocking, so this may provide a performance increase. The BIOS setting
for your card is printed at server start-up. Often, "low-cost" cards 
use the S3 default of 50MHz. This can often be exceeded with faster 
memory, some cards may function reliably at 60 or 65 MHz (even higher
on some recent /DX and /GX cards). Note
that S3 only officially supports an MCLK of 50MHz and XFree86 does not
encourage exceeding those specs.
*** Note: This option should not be preceded by the "Option" keyword!
</itemize>

Acceleration and graphic engine:

<itemize> 
<item>"noaccel" turns off all acceleration
<item>"fifo_aggressive", "fifo_moderate" and "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 ("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 should increase performance, so you should at
least use "fifo_conservative" (this uses the chip defaults).
</itemize>

PCI options:

<itemize>
<item>"pci_burst_on" will enable PCI burst mode. This should work on all but a
few "broken" PCI chipsets, and will increase performance.
<item>"pci_retry" will allow the driver to rely on PCI Retry to program the 
ViRGE registers. "pci_burst_on" 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. A possible side-effect is that it may interfere with
DMA operations on the PCI bus (e.g. sound cards, floppy drive).
</itemize>

Cursor:

<itemize>
<item>"hw_cursor" turns on the hardware cursor.
</itemize>

Color depth options and limitations:

<itemize>
<item>Pixel multiplexing is used above 80MHz for 8bpp on the ViRGE. 
<item>15bpp is supported, use "-bpp 15" as an option to the server.
<item>24bpp is supported using the STREAMS engine.
<item>32bpp uses STREAMS as well; however, because the ViRGE does not really 
support 32 bpp "natively", acceleration is quite limited.
<item>Both 24bpp and 32bpp do not support interlace modes.  
<item>32bpp is limited to a width of < 1024 pixels.  (1024x768 is not possible,
even if you have the memory.)  This is a hardware limit of ViRGE chips.
</itemize>


<sect1>Hints for LCD configuration (S3 ViRGE/MX)
<p>
If LCD is active the CRT will always output 1024x768 (or whatever is 
the _physical_ LCD size) and smaller modes are zoomed to fit on the LCD
unless you specify Option "lcd_center" in the device section.

The pixel clock for this physical size (e.g. 1024x768) mode...
<itemize>
<item>...can explicitly set in the config file (device section) with  e.g. `Set_LCDClk 70'
(resulting 70 MHz pixel clock being used for all modes when LCD is on)
<item>...is taken from the _first_ mode in the modes line iff this mode's display size
is the same as the physical LCD size
<item>...the default LCD pixel clock of BIOS initialisation setup is used.  
This value is output at server startup in the line `LCD size ...' 
unless you're specifying a value using `Set_LCDClk ...'
</itemize>

If LCD is _not_ active, the normal mode lines and pixel clocks 
are used for the VGA output.

Whenever you switch output sources with Fn-F5 or similar,
the Xserver won't get informed and pixel clock and other settings are wrong.
Because of this you have to switch modes _after_ switch output sources!
Then the server will check which outputs are active and select the correct
clocks etc.  
So the recommended key sequence to switch output is

	Fn-F5  Ctrl-Alt-Plus  Ctrl-Alt-Minus

and everything should be ok..  

on the Toshiba keypad you can first hold down Ctrl-Alt, then press `Fn' additionally 
before pressing Plus/Minus too to avoid to explicitly enable/disable 
the numeric keypad for mode switching.



<sect>Authors
<p>

<sect1> XF86_S3V server
Harald Koenig <it>&lt;koenig@tat.physik.uni-tuebingen.de&gt;</it>
<p>

and:

<itemize>
<item>Kevin Brosius <it>Cobra@compuserve.com</it>
<item>Berry Dijk <it>berry_dijk@tasking.nl</it>
<item>Dirk Hohndel <it>hohndel@XFree86.Org</it>
<item>Huver Hu <it>huver@amgraf.com</it>
<item>Dirk Vangestel <it>gesteld@sh.bel.alcatel.be</it>
</itemize>

<sect1> XF86_SVGA ViRGE driver
<p>

Sebastien Marineau <it>&lt;marineau@genie.uottawa.ca&gt;</it>

and: 

<itemize>
<item>Harald Koenig <it>&lt;koenig@tat.physik.uni-tuebingen.de&gt;</it>
<item>Kevin Brosius <it>Cobra@compuserve.com</it>
</itemize>

<verb>
$XFree86: xc/programs/Xserver/hw/xfree86/doc/sgml/S3V.sgml,v 3.3.2.8 1998/02/27 04:53:51 dawes Exp $
</verb>

</article>
