Vesafb mini-HOWTO Alex Buell, alex.buell@tahallah.demon.co.uk 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 jeff@planetfall.com · Francis Devereux f.devereux@cs.ucl.ac.uk · Andreas Ehliar ehliar@futurniture.se · Martin McCarthy marty@ehabitat.demon.co.uk · Simon Kenyon simon@koala.ie · David Ford david@kalifornia.com · Chris Black cblack@cmpteam4.unil.ch · N Becker nbecker@fred.net · Bob Tracy rct@gherkin.sa.wlk.com · Marius Hjelle marius.hjelle@roman.uib.no · Aaron Tiensivu tiensivu@pilot.msu.edu and of course the authors of the framebuffer devices: · Gerd Knorr kraxel@cs.tu-berlin.de · Geert Uytterhoeven Geert.Uytterhoeven@cs.kuleuven.ac.be · Martin Mares mj@ucw.cz · 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.