path: root/Documentation/fb/sisfb.txt
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authorLinus Torvalds <>2005-04-16 15:20:36 -0700
committerLinus Torvalds <>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/fb/sisfb.txt
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+What is sisfb?
+sisfb is a framebuffer device driver for SiS (Silicon Integrated Systems)
+graphics chips. Supported are:
+- SiS 300 series: SiS 300/305, 540, 630(S), 730(S)
+- SiS 315 series: SiS 315/H/PRO, 55x, (M)65x, 740, (M)661(F/M)X, (M)741(GX)
+- SiS 330 series: SiS 330 ("Xabre"), (M)760
+Why do I need a framebuffer driver?
+sisfb is eg. useful if you want a high-resolution text console. Besides that,
+sisfb is required to run DirectFB (which comes with an additional, dedicated
+driver for the 315 series).
+On the 300 series, sisfb on kernels older than 2.6.3 furthermore plays an
+important role in connection with DRM/DRI: Sisfb manages the memory heap
+used by DRM/DRI for 3D texture and other data. This memory management is
+required for using DRI/DRM.
+Kernels >= around 2.6.3 do not need sisfb any longer for DRI/DRM memory
+management. The SiS DRM driver has been updated and features a memory manager
+of its own (which will be used if sisfb is not compiled). So unless you want
+a graphical console, you don't need sisfb on kernels >=2.6.3.
+Sidenote: Since this seems to be a commonly made mistake: sisfb and vesafb
+cannot be active at the same time! Do only select one of them in your kernel
+How are parameters passed to sisfb?
+Well, it depends: If compiled statically into the kernel, use lilo's append
+statement to add the parameters to the kernel command line. Please see lilo's
+(or GRUB's) documentation for more information. If sisfb is a kernel module,
+parameters are given with the modprobe (or insmod) command.
+Example for sisfb as part of the static kernel: Add the following line to your
+ append="video=sisfb:mode:1024x768x16,mem:12288,rate:75"
+Example for sisfb as a module: Start sisfb by typing
+ modprobe sisfb mode=1024x768x16 rate=75 mem=12288
+A common mistake is that folks use a wrong parameter format when using the
+driver compiled into the kernel. Please note: If compiled into the kernel,
+the parameter format is video=sisfb:mode:none or video=sisfb:mode:1024x768x16
+(or whatever mode you want to use, alternatively using any other format
+described above or the vesa keyword instead of mode). If compiled as a module,
+the parameter format reads mode=none or mode=1024x768x16 (or whatever mode you
+want to use). Using a "=" for a ":" (and vice versa) is a huge difference!
+Additionally: If you give more than one argument to the in-kernel sisfb, the
+arguments are separated with ",". For example:
+ video=sisfb:mode:1024x768x16,rate:75,mem:12288
+How do I use it?
+Preface statement: This file only covers very little of the driver's
+capabilities and features. Please refer to the author's and maintainer's
+website at for more
+information. Additionally, "modinfo sisfb" gives an overview over all
+supported options including some explanation.
+The desired display mode can be specified using the keyword "mode" with
+a parameter in one of the follwing formats:
+ - XxYxDepth or
+ - XxY-Depth or
+ - XxY-Depth@Rate or
+ - XxY
+ - or simply use the VESA mode number in hexadecimal or decimal.
+For example: 1024x768x16, 1024x768-16@75, 1280x1024-16. If no depth is
+specified, it defaults to 8. If no rate is given, it defaults to 60Hz. Depth 32
+means 24bit color depth (but 32 bit framebuffer depth, which is not relevant
+to the user).
+Additionally, sisfb understands the keyword "vesa" followed by a VESA mode
+number in decimal or hexadecimal. For example: vesa=791 or vesa=0x117. Please
+use either "mode" or "vesa" but not both.
+Linux 2.4 only: If no mode is given, sisfb defaults to "no mode" (mode=none) if
+compiled as a module; if sisfb is statically compiled into the kernel, it
+defaults to 800x600x8 unless CRT2 type is LCD, in which case the LCD's native
+resolution is used. If you want to switch to a different mode, use the fbset
+shell command.
+Linux 2.6 only: If no mode is given, sisfb defaults to 800x600x8 unless CRT2
+type is LCD, in which case it defaults to the LCD's native resolution. If
+you want to switch to another mode, use the stty shell command.
+You should compile in both vgacon (to boot if you remove you SiS card from
+your system) and sisfb (for graphics mode). Under Linux 2.6, also "Framebuffer
+console support" (fbcon) is needed for a graphical console.
+You should *not* compile-in vesafb. And please do not use the "vga=" keyword
+in lilo's or grub's configuration file; mode selection is done using the
+"mode" or "vesa" keywords as a parameter. See above and below.
+If using XFree86 or, it is recommended that you don't use the "fbdev"
+driver but the dedicated "sis" X driver. The "sis" X driver and sisfb are
+developed by the same person (Thomas Winischhofer) and cooperate well with
+each other.
+SVGALib, if directly accessing the hardware, never restores the screen
+correctly, especially on laptops or if the output devices are LCD or TV.
+Therefore, use the chipset "FBDEV" in SVGALib configuration. This will make
+SVGALib use the framebuffer device for mode switches and restoration.
+(Some) accepted options:
+off - Disable sisfb. This option is only understood if sisfb is
+ in-kernel, not a module.
+mem:X - size of memory for the console, rest will be used for DRI/DRM. X
+ is in kilobytes. On 300 series, the default is 4096, 8192 or
+ 16384 (each in kilobyte) depending on how much video ram the card
+ has. On 315/330 series, the default is the maximum available ram
+ (since DRI/DRM is not supported for these chipsets).
+noaccel - do not use 2D acceleration engine. (Default: use acceleration)
+noypan - disable y-panning and scroll by redrawing the entire screen.
+ This is much slower than y-panning. (Default: use y-panning)
+vesa:X - selects startup videomode. X is number from 0 to 0x1FF and
+ represents the VESA mode number (can be given in decimal or
+ hexadecimal form, the latter prefixed with "0x").
+mode:X - selects startup videomode. Please see above for the format of
+ "X".
+Boolean options such as "noaccel" or "noypan" are to be given without a
+parameter if sisfb is in-kernel (for example "video=sisfb:noypan). If
+sisfb is a module, these are to be set to 1 (for example "modprobe sisfb
+Thomas Winischhofer <>
+May 27, 2004