Table of Contents


sis - SiS video driver


Section "Device"
  Identifier "devname"
  Driver "sis"


sis is an XFree86 driver for SiS video chips. The driver is accelerated, and provides support for 8, 16 and 24 colordepths. XVideo, Render and other extensions are supported as well.

Supported Hardware

The sis driver supports PCI and AGP video cards based on the following chipsets:

SiS5597/5598 SiS530/620 SiS6326/AGP/DVD SiS300/305 SiS540 SiS630/730 SiS315/H/PRO SiS550 SiS650/651/650M/740 SiS330 (Xabre)

In the following text, the following terms are used:

old series for SiS5597/5598, 530/620 and 6326/AGP/DVD

300 series for SiS300/305, 540 and 630/730

310/325/330 series for SiS315/H/PRO, 550 and 650/651/650M/740, 330

Configuration Details

Please refer to XF86Config(5) for general configuration details. This section only covers configuration details specific to this driver. Please note that support for the SiS330 is new and there may be some problems.

1. For all supported chipsets

The following driver Options are supported on all chipsets:

Option "NoAccel" "boolean"
Disable or enable 2D acceleration. Please note: On chipsets with XVideo support, this also disables XVideo. Default: acceleration is enabled.
Option "HWCursor" "boolean"
Enable or disable the HW cursor. Default: HWCursor is on.
Option "SWCursor" "boolean"
The opposite of HWCursor. Default: SWCursor is off.
Option "Rotate" "CW"
Rotate the display clockwise. This mode is unaccelerated, and uses the Shadow Frame Buffer layer. Default: no rotation.
Option "Rotate" "CCW"
Rotate the display counterclockwise. This mode is unaccelerated, and uses the Shadow Frame Buffer layer. Default: no rotation.
Option "ShadowFB" "boolean"
Enable or disable use of the shadow framebuffer layer. Default: Shadow framebuffer is off.

2. Old series specific information

The driver will auto-detect the amount of video memory present for all these chips, but in the 6326 case, it will limit the memory size to 4MB. This is because the 6326's 2D engine can only address 4MB. The remaining memory seems to be intended for 3D texture data, since only the 3D engine can address RAM above 4MB. However, you can override this forced limitation using the "VideoRAM" option in the device section if your board has more than 4MB and you need to use it. However, 2D acceleration, Xvideo and the HWCursor will be disabled in this case.

The driver will also auto-detect the maximum dotclock and DAC speed. If you have problems getting high resolutions because of dot clock limitations, try using the "DacSpeed" option, also in the device section. However, this is not recommended for the 6326. For this chipset, the driver has two built-in modes for high resolutions which you should use instead. These are named "SIS1280x1024-75" and "SIS1600x1200-60" and they will be added to the list of default modes. To use these modes, just place them in your Screen section. Example:

Modes "SIS1600x1200-60" "SIS1280x1024x75" "1024x768" ...

1280x1024 is only available at 8, 15 and 16bpp. 1600x1200 is available at 8bpp only.

TV support for the 6326

TV output is supported on the 6326. The driver will auto detect a TV connected, and in this case add the following modes to the list of default modes: "PAL800x600", "PAL800x600U", "PAL720x540", "PAL640x480", "NTSC640x480", "NTSC640x480U" and "NTSC640x400". Use these modes like the hi-res modes described above.

The following driver Options are supported on the old series:

Option "TurboQueue" "boolean"
Enable or disable TurboQueue mode. Default: off for SIS530/620, on for the others
Option "FastVram" "boolean"
Enable or disable FastVram mode. Enabling this sets the video RAM timing to only one cycle per read operation instead of two cycles. Disabling this will set 2 cycles for read and write operations. Leaving this option out uses the default. Default: off for read, on for write.
Option "NoHostBus" "boolean"
(SiS5597/5598 only). Disable CPU-to-VGA host bus support. This speeds up CPU to video RAM transfers. Default: Host bus is enabled.
Option "NoXVideo" "boolean"
Disable XV (XVideo) extension support. Default: XVideo is on.
Option "TVStandard" "string"
(6326 only) Possible parameters are PAL or NTSC. The default is set by a jumper on the card.
Option "TVXPosOffset" "integer"
(6326 only) This option allows horizontal relocation the TV output. The range is from -16 to 16.
Option "TVYPosOffset" "integer"
(6326 only) This option allows vertical relocation the TV output. The range is from -16 to 16.
Option "SIS6326TVEnableYFilter" "boolean"
(6326 only) This option allows enabling/disabling the Y filter for TV output.
Option "SIS6326TVAntiFlicker" "string"
(6326 only) This option allow enabling/disabling the anti flicker facility for TV output. Possible parameters are OFF, LOW, MED, HIGH or ADAPTIVE. By experience, ADAPTIVE yields the best results.

2. 300 and 310/325/330 series specific information

The 300 and 310/325/330 series very often come with a video bridge for controlling LCD and TV output. Hereinafter, the term CRT1 refers to the VGA output of the chip, and CRT2 refers to either LCD, TV or secondary VGA. Due to timing reasons, only one CRT2 output can be active at the same time. But this limitation does not apply to using CRT1 and CRT2 at the same time which makes it possible to run the driver in dual head mode.

The driver supports the following video bridges:

SiS301 SiS301B SiS301LV SiS302B SiS302LV

Instead of a video bridge, some machines have a LVDS transmitter to control LCD panels, and a Chrontel 7005 or 7019 for TV output. All these are supported as well.

About TV output

On the SiS301 and the Chrontel 7005, only resolutions up to 800x600 are supported. On all others, resolutions up to 1024x768 are supported.

About XVideo support

XVideo is supported on all chipsets of both families. However, there are some differences in hardware features which cause limitations. The 300 series as well as the SiS550, 650M, 651 and 330 support two video overlays. The SiS315/H/PRO and 650/740 support only one such overlay. On chips with two overlays, one overlay is used for CRT1, the other for CRT2. On the other chipsets, the option "XvOnCRT2" can be used to select the desired output channel.

About dual-head support

Dual head mode has some limitations as regards color depth and resolution. Due to memory bandwidth limits, CRT1 might have a reduced refresh rate if running on higher resolutions than 1280x1024.

Colordepth 8 is not supported when running in dual head mode.

The following driver Options are supported on the 300 and 310/325 series:

Option "NoXVideo" "boolean"
Disable XV (XVideo) extension support. Default: XVideo is on.
Option "XvOnCRT2" "boolean"
On chipsets with only one video overlay, this option can used to bind the overlay to CRT1 ( if a monitor is detected and if this option is either unset or set to false ) or CRT2 ( if a CRT2 device is detected or forced, and if this option is set to true ). If either only CRT1 or CRT2 is detected, the driver decides automatically. Default: overlay is used on CRT1
Option "ForceCRT1" "boolean"
The BIOS detects VGA monitors connected to CRT1 at boot time and the X driver by default relies on the information passed by the BIOS. However, some old monitors are not detected correctly. If this is the case, or if you connected the VGA monitor after you booted the machine, you may set this option to true in order to make the X driver ignore the information from the BIOS and initialize CRT1 anyway. If this option is set to false , the driver will switch off CRT1 and thus save memory bandwidth. Default: auto detect CRT1
Option "ForceCRT2Type" "string"
Force display type to one of: NONE , TV , SVIDEO , COMPOSITE , SCART, , LCD , VGA ; NONE will disable CRT2. The SVIDEO, COMPOSITE and SCART parameters can be used to force the driver to use a specific TV output connector (if present). Default: auto detect.
Option "PanelDelayCompensation" "integer"
This option is only for machines with a 300 series chipset and either a SiS301B video bridge or a LVDS transmitter. Different LCD panels require different delay compensation values. In most cases, the driver can autodetect this value. However, due to bad BIOS design this might fail in rare cases. If your LCD shows small horizontal waves, set the parameter of this option first to 4 , 32 or 24 and if the problem persists, try using other values between 4 and 60 in steps of 4.
Option "UseROMData" "boolean"
The driver reads some data from the BIOS ROM, especially LCD dependent information. If the folks at SiS some day decide to change the location of this data inside the BIOS image, the display might not be initialized correctly. In order to prevent this, set this option's parameter to false. Default: ROM data is used
Option "TVStandard" "string"
Force the TV standard to either PAL or NTSC. On some machines with 630, 730 or 650/740, PALM and PALN are supported as well. Default: BIOS setting.
Option "TVXPosOffset" "integer"
This option allows horizontal relocation the TV output. The range is from -32 to 32. Not supported on the Chrontel 7019 yet.
Option "TVYPosOffset" "integer"
This option allows vertical relocation the TV output. The range is from -32 to 32. Not supported on the Chrontel 7019 yet.
Option "CHTVOverscan" "boolean"
On machines with a Chrontel TV encoder, this can be used to force the TV mode to overscan or underscan. True means overscan, false means underscan. Default: BIOS setting.
Option "CHTVSuperOverscan" "boolean"
On machines with a Chrontel 7005 TV encoder, this option enables a super-overscan mode. This is only supported if the TV standard is PAL. Super overscan will produce an image on the TV which is larger than the viewable area.

3. 300 series specific information

DRI is supported on the 300 series only. DRI requires the kernel's SiS framebuffer driver ( sisfb ) and some other modules which come with either the kernel or XFree86.

Sisfb takes care of memory management for texture data. In order to prevent the X driver and sisfb from overwriting each others video memory, sisfb reserves an amount of video memory for the X driver. This amount can either be selected using sisfb's mem parameter, or auto-selected depending on the amount of total video RAM available. However, the X driver needs to know about the amount of RAM sisfb reserved. For this purpose, the

Option "MaxXFBMem" "integer"


At the moment (2002), the SiS DRI driver is not maintained, lacks support for memory swapping and has a few bugs. If you intend to use DRI, I recommend setting the total video memory in the BIOS to 64MB in order to at least overcome the lack of memory swap functions.

Sisfb can be used for memory management only, or as a complete framebuffer driver. If you start sisfb with a valid mode (ie you gain a graphical console), the X driver can communicate with sisfb and doesn't require setting the "MaxXFBMem" option at all. The X driver will receive enough information from sisfb in this case.

However, if you use sisfb for memory management only, ie you started sisfb with mode=none and still have a text mode console, there is no communication between sisfb and the X driver. In this case, you need to set "MaxXFBMem" to the same value as you gave sisfb with its mem parameter. If you didn't specify any mem parameter, sisfb will reserve

12288KB if more than 16MB of total video RAM is available,
8192KB if between 12 and 16MB of video RAM is available,
4096KB in all other cases.

Then you need to specify any of these amounts as the parameter for the "MaxXFBMem" option. The value is to be given without 'KB'.

Known Bugs

For some reason, PAL TV output on the SiS301LV bridge is only black and white. NTSC is OK, though.

LCD panels with a resolution of 1280x1024 do not work correctly.

See Also

XFree86(1) , XF86Config(5) , xf86config(1) , Xserver(1) , X(7) for more information and updates


Authors include: Alan Hourihane, Mike Chapman, Juanjo Santamarta, Mitani Hiroshi, David Thomas, Sung-Ching Lin, Ademar Reis, Thomas Winischhofer

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