Vesafb mini-HOWTO
 Alex Buell, [email protected]
 v0.5, 2 August 1998

 This document describes how to use the vesafb device in Linux with a
 VESA 2.0 compliant graphic card on Intel platforms.
 ______________________________________________________________________

 Table of Contents


 1. Contributors

 2. What is vesafb?

 3. What is a framebuffer device?

 4. How do I activate the vesafb drivers?

 5. What VESA modes are available to me?

 6. Is there a X11 driver for vesafb?

 7. Can I make vesafb as a module?

 8. Miscellaneous/Caveats



 ______________________________________________________________________

 1.  Contributors

 Thanks go to these people listed below who helped improve the vesafb
 HOWTO.


 �  Jeff Noxon [email protected]

 �  Francis Devereux [email protected]

 �  Andreas Ehliar [email protected]

 �  Martin McCarthy [email protected]

 �  Simon Kenyon [email protected]

 �  David Ford [email protected]

 �  Chris Black [email protected]

 �  N Becker [email protected]

 �  Bob Tracy [email protected]

 �  Marius Hjelle [email protected]

 �  Aaron Tiensivu [email protected]

 and of course the authors of the framebuffer devices:


 �  Gerd Knorr [email protected]

 �  Geert Uytterhoeven [email protected]

 �  Martin Mares [email protected]

 �  Anyone else, stand up and be counted. :o)


 2.  What is vesafb?

 Vesafb is a framebuffer driver for Intel architecture that works with
 VESA 2.0 compliant graphic cards. It is closely related to the
 framebuffer device drivers in the kernel.

 vesafb is a display driver that enables the use of graphical modes on
 your Intel platform for bitmapped text consoles. It can also display a
 logo, which is probably the main reason why you'd want to use vesafb
 :o)

 Unfortunately, you can not use vesafb successfully with VESA 1.2
 cards.  This is because these 1.2 cards do not use framebuffering. It
 may be that someone will write a vesafb12 device driver for these
 cards, but this will use up precious kernel memory. :o(

 There is however a potential workaround to add VESA 2.0 extensions for
 your legacy VESA 1.2 card. You may be able to download a TSR type
 program that will run from DOS, and used in cojunction with loadlin,
 can help configure the card for the appropriate graphic console modes.
 Note that this will not always work, as an example some Cirrus Logic
 cards such as the VLB 54xx series are mapped to a range of memory
 addresses (for example, within the 15MB-16MB range) for frame
 buffering which preludes these from being used successfully with
 systems that have more than 32MB of memory. [There is a way to make
 this work, i.e. if you have a BIOS option to leave a memory hole at
 15MB-16MB range, it might work, but I've been told that Linux doesn't
 support this] If you wish to experiment with this option, there are
 plenty of TSR style programs available, a prime example is UNIVBE,
 which can be found on the Internet.


 3.  What is a framebuffer device?

 A framebuffer device is an abstraction for the graphic hardware. It
 represents the frame buffer of some video hardware, and allows
 application software to access the graphic hardware through a well-
 defined interface, so that the software doesn't need to know anything
 about the low-level interface stuff [Taken from Geert Uytterhoeven's
 framebuffer.txt in the linux kernel sources]


 4.  How do I activate the vesafb drivers?

 [Note: The information is based on what I know and have achieved using
 the Linux kernel v2.1.112 on a P75+ with an ATI VideoExpress 2MB
 graphic card.  Feel free to email me with information/special cases
 for different graphic cards]

 Assuming you are using menuconfig, you will need to do the following
 steps:

 Go into the Code Maturity Level menu, and enable the prompt for
 development and/or incomplete drivers [note this may change for future
 kernels - when this happens, this HOWTO will be revised]

 Go into the Console Drivers menu, and enable the following:


 �  VGA Text Console

 �  Video Selection Support

 �  Support for frame buffer devices (experimental)

 �  VESA VGA Graphic console

 �  Advanced Low Level Drivers

 �  Select Mono, 2bpp, 4bpp, 8bpp, 16bpp, 24bpp and 32bpp packed

 �  pixel drivers

 �  VGA character/attributes support

 VGA Chipset Support (text only) - vgafb - used to be part of the list
 above, but it has been removed as it is now deprecated and no longer
 supported. It will be removed shortly. Use VGA Text Console instead.

 Ensure that the Mac variable bpp packed pixel support is not enabled.
 [As of 2.1.111, this seems to get enabled if Advanced Low Level
 Drivers is initally selected]

 Make sure these aren't going to be modules. [Not sure if it's possible
 to build them as modules yet - please correct me on this]

 Then rebuild the kernel, modify /etc/lilo.conf to include the VGA=ASK
 parameter, and run lilo, this is required in order for you to be able
 to select the modes you wish to use.

 Reboot the kernel, and as a simple test, try entering 0301 at the VGA
 prompt (this will give you 640x480 @ 256), and you should be able to
 see a cute little Penguin logo.

 Once you can see that's working well, you can explore the various VESA
 modes (see below) and decide on the one that you like the best, and
 hardwire that into the "VGA=x" parameter in lilo.conf. When you have
 chosen the one you like the best, look up the decimal equivalent from
 the tables below and use the corresponding decimal number (i.e. for
 1280x1024 @ 256, you just use "VGA=775"), and re-run lilo. That's all
 there it is to it. For further references, read the LoadLin/LILO
 HOWTOs.


 5.  What VESA modes are available to me?

 This really depends on the type of VESA 2.0 compliant graphic card
 that you have in your system, and the amount of video memory
 available. This is just a matter of testing which modes work best for
 your graphic card.

 The following table shows the mode numbers you can input at the VGA
 prompt (actually these numbers are plus 0x200 to make it easier to
 refer to the table)


 Colours   640x480 800x600 1024x768 1280x1024 1600x1200
 --------+---------------------------------------------
 256     |  0301    0303     0305     0307      031C
 32,768  |  0310    0313     0316     0319      031D
 65,536  |  0311    0314     0317     031A      031E
 16.8M   |  0312    0315     0318     031B      031F



 For convienence, here is the same table in decimal terms

 Colours   640x480 800x600 1024x768 1280x1024 1600x1200
 --------+---------------------------------------------
 256     |   769     771      773      775       796
 32,768  |   784     787      790      793       797
 65,536  |   785     788      791      794       798
 16.8M   |   786     789      792      795       799



 [The author would be happy if you could supply him with additional
 03xx numbers for additional modes i.e 1152x900?]


 6.  Is there a X11 driver for vesafb?

 Yes, there is, actually. You will need to use the XF86_FBdev driver if
 for some reason your current X11 driver doesn't like vesafb. Go to
 http://www.xfree86.org, and download the X332servonly.tgz archive,
 unpack, configure it by editing xc/config/cf/xf86site.def, and
 uncomment the #define for XF68FBDevServer. Don't worry about the m68k
 reference, it supports Intel platforms. Then build the whole thing -
 it'll take a long time though as it's a large source tree.

 There is as of yet, no pre-compiled XF86_FBdev binary available, but I
 understand that Debian may be working on this; and they will be able
 to produce both libc5/glibc2 variants.

 There have been reports that X11 is non functional on certain graphic
 cards with this vesafb feature enabled, if this is happening, try the
 new XF86_FBdev driver for X11.

 This driver, along with vesafb can also help run X11 in higher graphic
 resolutions with certain graphic chipsets which are not supported by
 any of the current X11 drivers. Examples are MGA G-200 et. al.

 Hopefully the X11 problems with supported graphic cards will be fixed
 in future releases.


 7.  Can I make vesafb as a module?

 As of v2.1.112, vesafb can't be modularised, although at some point in
 time, the developer of vesafb may decide to modify the sources for
 modularising. Note that even if modularising is possible, at boot time
 you will not be able to see any output on the display until vesafb is
 'modprobed'. It's probably a lot wiser to leave it in the kernel, for
 these cases when there are booting problems.


 8.  Miscellaneous/Caveats

 This is current only for v2.1.112 of the Linux kernel. This HOWTO will
 be constantly updated as kernel development progresses. Feel free to
 email the author with information/flames :o)

 Another gotcha is that scrollback buffering does not work yet. May be
 fixed in future releases.

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