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<A HREF="tseng.html"><EM> Information for Tseng Chipset Users</EM></A>
 <b>:</b> <EM>general options in the <code>XF86Config</code> file </EM><BR>
<b>Previous:</b> <A HREF="tseng7.html"><EM>Basic configuration </EM></A><BR>
<b>Next:</b> <A HREF="tseng9.html"><EM>linear memory base address (MemBase) issues </EM></A>


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  <H2><A NAME="8"></A>8. general options in the <code>XF86Config</code> file </H2>

<p>The following options are of particular interest to the Tseng driver. Each
of them must be specified in the <code>svga</code>' driver section of the
<code>XF86Config</code>
file, within the <code>Screen</code> subsections of the depths to which they are
applicable (you can enable options for all depths by specifying them in the
Device section).
<dl>
<dt><b>Option "noaccel"</b><dd><p>(ET4000W32p, et6000)
This option will disable the use of any accelerated functions. This
is likely to help with some problems related to DRAM timing, high
dot clocks, and bugs in accelerated functions, at the cost of
performance (which will still be reasonable on a local or PCI bus).
This option applies only to those chips where acceleration is
supported.</p>
<dt><b>Option "fast_dram" "slow_dram" </b><dd><p>These options set the DRAM speed of certain cards where it applies. </p>
<p>The <code>"slow_dram"</code> option is always enabled on ET4000, and
ET4000W32. If enabled, it slows down DRAM timing, which may avoid
some memory-related problems. If your card starts up with a black
screen (and possibly a system hang), this option might be needed.</p>
<p>The <code>"fast_dram"</code> option will cause the driver to speed up
DRAM timings, which may also avoid screen-related problems
(streaking, stripes, garbage, ...). It may also increase those very
same effects.</p>
<p>All in all, these are potentially dangerous options: they could
crash your machine as soon as you start the server. Use them with
caution.</p>
<dt><b>option "w32_interleave_off" "w32_interleave_on"   (W32i, W32p)</b><dd><p>Force memory interleaving off or on. W32i and W32p chips can
increase memory bandwidth when they have 2MB or more video memory.
Normally the VGA BIOS sets the W32i or W32p chip to the correct
mode. If you suspect problems with memory sizing or interleaving,
fooling around with these options may improve the situation. It may
also make things worse. These options are not normally needed: the
server will use the correct value automatically. Setting this option
the wrong way will result in a completely distorted display.</p>
<dt><b>option "pci_burst_off" "pci_burst_on"   (W32p)</b><dd><p>This option disables or enables PCI bursts on the W32p chip if it's
a PCI card. Normally, a good BIOS will set the motherboard and the
VGA card to the same setting, but if both don't match, you may
experience garbage on the screen (e.g. mouse droppings). These
options allow you to match the W32p burst setting to the motherboard
setting.</p>
<dt><b>videoram 1024 (or another value)   (all chips)</b><dd><p>This option will override the detected amount of video memory, and
pretend the given amount of memory is present on the card. This is
useful on cards with 2Mbyte of memory whose DRAM configuration is
not compatible with the way the driver enables the upper megabyte of
memory, or if the memory detection goes wrong. It must be specified
in the Device section.</p>
<dt><b>Clockchip "et6000"  (et6000)</b><dd><p>This enables programmable clocks, but obviously only on the et6000.
It must be specified in the Device section. Normally the server will
automatically use this feature when it detects an ET6000. Use it
only when you suspect auto-detection is not working. Note that some
frequencies may be unstable (resulting in a `Wavy' screen). Only
tried and tested frequencies (like the default clocks) are
guaranteed to be stable. If this happens, try a slightly different
frequency in the modeline (like 0.5 MHz more or less). The monitor
should still be capable of syncing to this frequency, but the
clockchip may already be outside an unstable region.</p>
<dt><b>Option "linear"  (ET4000W32i, ET4000W32p, ET6000)</b><dd><p>This enables linear addressing, which is the mapping of the entire
framebuffer to a high address beyond system memory, making the full
length of the framebuffer directly accessible. In this way, slow
SVGA bank switching (where only a small fraction of the framebuffer
is visible at one time) is not necessary. It enhances performance at
256 colors, and is currently required for 16bpp, 24bpp, and 32bpp.</p>
<dt><b>MemBase 0xE0000000. (or a different address) (ET4000W32, ET6000)</b><dd><p>This sets the physical memory base address of the linear
framebuffer. It must be specified in the Device section. It may be
required for non-PCI linear addressing configurations, and might be
useful for PCI-based systems where auto-detection fails. However,
almost all PCI systems will not need this.</p>
<p>Read the section on linear memory base address issues below!</p>
<p>Read the section on linear memory base address issues below!
(Message repeated for a very good reason)</p>
<p>Use this option ONLY if you have trouble with the default MemBase
used by the server, or if the server explicitly states that you must
provide one.</p>
<dt><b>Option "pci_retry" (ET4000W32p on PCI bus, ET6000)</b><dd><p>This enables the PCI bus retry function, which is a performance
enhancing mode for local bus or PCI bus-based systems, where the VGA
controller will put the bus in a hold state (sort of like
wait-states) when the server tries to start a new accelerated
operation but the accelerator is still busy with the previous
operation.</p>
<p>This is the fastest way to drive a VGA card (no busy-waiting loops
needed), but it also stresses some hardware that is timing-dependent
(tape drives, sound cards, etc). See also the trouble shooting
section.</p>
</dl>
</p>

 <HR NOSHADE>
<A HREF="tseng.html"><EM> Information for Tseng Chipset Users</EM></A>
 <b>:</b> <EM>general options in the <code>XF86Config</code> file </EM><BR>
<b>Previous:</b> <A HREF="tseng7.html"><EM>Basic configuration </EM></A><BR>
<b>Next:</b> <A HREF="tseng9.html"><EM>linear memory base address (MemBase) issues </EM></A>



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