How to use it?¶

Switching modes is done using the video=matroxfb:vesa:… boot parameteror usingfbset program.

If you want, for example, enable a resolution of 1280x1024x24bpp you shouldpass to the kernel this command line: “video=matroxfb:vesa:0x1BB”.

You should compile in both vgacon (to boot if you remove you Matrox frombox) and matroxfb (for graphics mode). You should not compile-in vesafbunless you have primary display on non-Matrox VBE2.0 device (seeDocumentation/fb/vesafb.rst for details).

Currently supported video modes are (through vesa:… interface, PowerMachas [as addon] compatibility code):

X11¶

XF{68,86}_FBDev should work just fine, but it is non-accelerated. On non-intelarchitectures there are some glitches for 24bpp videomodes. 8, 16 and 32bppworks fine.

Running another (accelerated) X-Server like XF86_SVGA works too. But (at least)XFree servers have big troubles in multihead configurations (even on firsthead, not even talking about second). Running XFree86 4.x accelerated mgadriver is possible, but you must not enable DRI - if you do, resolution andcolor depth of your X desktop must match resolution and color depths of yourvirtual consoles, otherwise X will corrupt accelerator settings.

SVGALib¶

Driver contains SVGALib compatibility code. It is turned on by choosing textualmode for console. You can do it at boot time by using videomode2,3,7,0x108-0x10C or 0x1C0. At runtime,fbset -depth 0 does this work.Unfortunately, after SVGALib application exits, screen contents is corrupted.Switching to another console and back fixes it. I hope that it is SVGALib’sproblem and not mine, but I’m not sure.

Configuration¶

You can pass kernel command line options to matroxfb withvideo=matroxfb:option1,option2:value2,option3 (multiple options should beseparated by comma, values are separated from options by:).Accepted options:

If you are not satisfied with videomode selected byvesa option, youcan modify it with these options:

If you know capabilities of your monitor, you can specify some (or all) ofmaxclk,fh andfv. In this case,pixclock is computed so thatpixclock <= maxclk, real_fh <= fh and real_fv <= fv.

Limitations¶

There are known and unknown bugs, features and misfeatures.Currently there are following known bugs:

• SVGALib does not restore screen on exit
• generic fbcon-cfbX procedures do not work on Alphas. Due to this,noaccel (and cfb4 accel) driver does not work on Alpha. So everyonewith access to/dev/fb* on Alpha can hang machine (you should restrictaccess to/dev/fb* - everyone with access to this device can destroyyour monitor, believe me…).
• 24bpp does not support correctly XF-FBDev on big-endian architectures.
• interlaced text mode is not supported; it looks like hardware limitation,but I’m not sure.
• Gxx0 SGRAM/SDRAM is not autodetected.
• If you are using more than one framebuffer device, you must boot kernelwith ‘video=scrollback:0’.
• maybe more…

And following misfeatures:

• SVGALib does not restore screen on exit.

• pixclock for text modes is limited by hardware to

  • 83 MHz on G200
  • 66 MHz on Millennium I
  • 60 MHz on Millennium II

  Because I have no access to other devices, I do not know specificfrequencies for them. So driver does not check this and allows you toset frequency higher that this. It causes sparks, black holes and otherpretty effects on screen. Device was not destroyed during tests. :-)

• my Millennium G200 oscillator has frequency range from 35 MHz to 380 MHz(and it works with 8bpp on about 320 MHz dotclocks (and changed mclk)).But Matrox says on product sheet that VCO limit is 50-250 MHz, so I believethem (maybe that chip overheats, but it has a very big cooler (G100 hasnone), so it should work).

• special mixed video/graphics videomodes of Mystique and Gx00 - 2G8V16 andG16V16 are not supported

• color keying is not supported

• feature connector of Mystique and Gx00 is set to VGA mode (it is disabledby BIOS)

• DDC (monitor detection) is supported through dualhead driver

• some check for input values are not so strict how it should be (you canspecify vslen=4000 and so on).

• maybe more…

And following features:

• 4bpp is available only on Millennium I and Millennium II. It is hardwarelimitation.
• selection between 1:5:5:5 and 5:6:5 16bpp videomode is done by -rgbaoption of fbset: “fbset -depth 16 -rgba 5,5,5” selects 1:5:5:5, anythingelse selects 5:6:5 mode.
• text mode uses 6 bit VGA palette instead of 8 bit (one of 262144 colorsinstead of one of 16M colors). It is due to hardware limitation ofMillennium I/II and SVGALib compatibility.

Benchmarks¶

It is time to redraw whole screen 1000 times in 1024x768, 60Hz. It istime for draw 6144000 characters on screen through /dev/vcsa(for 32bpp it is about 3GB of data (exactly 3000 MB); for 8x16 font in16 seconds, i.e. 187 MBps).Times were obtained from one older version of driver, now they are about 3%faster, it is kernel-space only time on P-II/350 MHz, Millennium I in 33 MHzPCI slot, G200 in AGP 2x slot. I did not test vgacon:

NOACCEL      8x16                 12x22      Millennium I  G200   Millennium I  G2008bpp    16.42         9.54   12.33         9.1316bpp   21.00        15.70   19.11        15.0224bpp   36.66        36.66   35.00        35.0032bpp   35.00        30.00   33.85        28.66ACCEL, nofastfont      8x16                 12x22                6x11      Millennium I  G200   Millennium I  G200   Millennium I  G2008bpp     7.79         7.24   13.55         7.78   30.00        21.0116bpp    9.13         7.78   16.16         7.78   30.00        21.0124bpp   14.17        10.72   18.69        10.24   34.99        21.0132bpp   16.15      16.16   18.73        13.09   34.99        21.01ACCEL, fastfont      8x16                 12x22                6x11      Millennium I  G200   Millennium I  G200   Millennium I  G2008bpp     8.41         6.01    6.54         4.37   16.00        10.5116bpp    9.54         9.12    8.76         6.17   17.52        14.0124bpp   15.00        12.36   11.67        10.00   22.01        18.3232bpp   16.18        18.29*  12.71        12.74   24.44        21.00TEXT      8x16      Millennium I  G200TEXT     3.29         1.50* Yes, it is slower than Millennium I.

Dualhead G400¶

Driver supports dualhead G400 with some limitations:

• secondary head shares videomemory with primary head. It is not problemif you have 32MB of videoram, but if you have only 16MB, you may haveto think twice before choosing videomode (for example twice 1880x1440x32bppis not possible).
• due to hardware limitation, secondary head can use only 16 and 32bppvideomodes.
• secondary head is not accelerated. There were bad problems with acceleratedXFree when secondary head used to use acceleration.
• secondary head always powerups in640x480@60-32 videomode. You have to usefbset to change this mode.
• secondary head always powerups in monitor mode. You have to use fbmatroxsetto change it to TV mode. Also, you must select at least 525 lines forNTSC output and 625 lines for PAL output.
• kernel is not fully multihead ready. So some things are impossible to do.
• if you compiled it as module, you must insert i2c-matroxfb, matroxfb_mavenand matroxfb_crtc2 into kernel.

Dualhead G450¶

Driver supports dualhead G450 with some limitations:

• secondary head shares videomemory with primary head. It is not problemif you have 32MB of videoram, but if you have only 16MB, you may haveto think twice before choosing videomode.
• due to hardware limitation, secondary head can use only 16 and 32bppvideomodes.
• secondary head is not accelerated.
• secondary head always powerups in640x480@60-32 videomode. You have to usefbset to change this mode.
• TV output is not supported
• kernel is not fully multihead ready, so some things are impossible to do.
• if you compiled it as module, you must insert matroxfb_g450 and matroxfb_crtc2into kernel.

Petr Vandrovec <vandrove@vc.cvut.cz>