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       svgalib.faq - frequently asked questions about svgalib


       I  (Matan  Ziv-Av),  added/changed some of the answers in this file, so
       some answers are mine, and some are Michael’s.

       List of (recently) frequently asked questions about svgalib. Esp. about
       it’s status and future. Please note that as of now all answers are just
       written by me, Michael Weller <>. I’d  like
       this to change. So email your suggestion (best of all: question and the

       Also, most questions deal with the status and future and my ideas about
       it.  Necessarily  they  contain my own private opinions on this. People
       may disagree and I’m sure I don’t have the best ideas about it  or  may
       even  be  completely  wrong. I don’t want to force anyone to agree with

       Also, I was asked about MY opinions, so I’m just presenting them  here.


       Q 1)   I   want  to  write  some  svgalib  application.  Where  is  the

       Q 2)   My board is not supported. What now?

       Q 3)   I get:

              You must be the owner of the current console to use svgalib.
              Not running in a graphics capable console, and  unable  to  find

              However, though logged in not directly from the linux console, I
              am the owner of the console.

       Q 4)   Is svgalib dead?

       Q 5)   There are so many Xfree drivers, why not just use them.

       Q 6)   Why not just use the VGA BIOS?.

       Q 7)   What about GGI?

       Q 8)   Why not just use X11?

       Q 9)   Now, again, what about the future of svgalib?

       Q 10)  Ok, just for completeness, what are  your  plans  about  svgalib

       Q 11)  Nice plan. But will it become true?


   Q 1)
       I want to write some svgalib application. Where is the documentation?

   A a)
       Well,  did  you really look at everything? The 0-README file in the top
       level directory contains all function prototypes  and  explanations  on
       how to call them.

       Yes, the documentation is short and/or confusing. Sorry, English is not
       my native tongue. Many people complain and want to  write  some  better
       documentation.  You  are  welcome  to do so! However, up to now, either
       people found the documentation  sufficient  once  they  looked  at  the
       correct  files or they just gave up. At least, I never heard from these
       people again.

       Also, svgalib comes with source. If in doubt: read it.

       Finally: Linux distributions include svgalib, but not  the  source  and
       README’s (or hide them so good noone finds them). Well, no problem, get
       full svgalib source, demos, readme’s from svgalib-*.tar.gz on any Linux
       FTP  server  in  your  vicinity.  Even  if you don’t dare to install or
       compile it, it contains the readme’s.

       Oh yes, there are some simple demos in the demos/ subdir.  They  should
       get you started.

       When  someone  writes  man(1)  manual  pages, a distribution might just
       install them. Please do not complain, write them, mail them to me.

   A b)
       Finally, I, Michael Weller wrote the manpages.  Looking  at  svgalib(7)
       should get you started. Additions and corrections are still welcome, of

   Q 2)
       My board is not supported. What now?


       a)     Contact the maintainers (see other README’s) and  check  out  if
              someone is working on a driver.

       b)     If so, contact them if you like and announce you’d be willing to
              test things or even help coding.

       c)     If not, write a driver. Get as many docs on  your  card  as  you
              can,  then  read  and understand the internals of svgalib (again
              read the README’s carefully!).

       Please understand that this is a free project. I will not go and buy  a
       similar  card  and  write a driver for you. I already wrote support for
       the hardware I have! I just do this as a hobby.  Because  I  don’t  get
       paid  for  this I can not just buy card & docu and spend much much time
       supporting whatever graphics card on earth exists.

       Also read below on the future of svgalib.

       If you don’t feel able to write a driver for whatever reason, please do
       not  complain  if other people don’t do it for you (because you are not
       better than they are).

   Q 3)
       I get:

       You must be the owner of the current console to use svgalib.
       Not running in a graphics capable console, and unable to find one.

       However, though logged in not directly from the linux console, I am the
       owner of the console.

       Alas,  some  programs  use  their suid root privilege and become a full
       root owned process. svgalib thinks they are run by root which does  not
       own the current console.  Defining ROOT_VC_SHORTCUT in Makefile.cfg and
       recompiling will allow svgalib to allocate a new VC. However,  it  will
       allow  any  person  which is able to exec that program to start in on a
       new console. Even if not logged in from the console at all.  Thus,  for
       security, you need to explicitly enable that root feature.

   Q 4)
       Is svgalib dead?

       This question comes up frequently esp. in recent times.

       The answer is, of course, no.

   Q 5)
       There are so many Xfree drivers, why not just use them.

       Well,  actually  much  of the code in there is actually already used by
       svgalib. Xfree coders worked on svgalib and vice versa.  But  honestly,
       do  not  expect  that a driver from Xfree can just be used for svgalib.
       The internal structures of Xfree and svgalib (and  GGI)  are  just  too
       different.  As  a  source  of  knowledge  and  for  one  or  the  other
       subroutine, the Xfree sources are invaluable however.

   Q 6)
       Why not just use the VGA BIOS?.

       Actually, we do. There is  now,  thanks  to  Josh  Vanderhoof,  a  VESA
       driver.   The  VESA  driver  does not work on all cards, even though it
       should.  It does not even work on all cards  where  vbetest  works.  If
       vbetest does not work it means the bios writers assumed it would always
       run in DOS, and used tricks (for delay, etc.)  that  can’t  work  under
       Linux. If vbetest works, but the VESA driver does not, I (Matan Ziv-Av)
       believe it is due to the following reason: The driver use VESA function
       4  (save/restore  video  state).  This  function  can’t  be  used  in a
       singletasking environment (DOS) and as such, some bios  writers  failed
       to  implement  it properly, and all the tests (which are run under DOS)
       failed to discover this.

       The VESA driver does work with many cards though.

   Q 7)
       What about GGI?

       Yes, GGI. Another long story. At first: Yes, I like the idea of  an  in
       kernel  graphics  driver.  I like it very much. And, yes, this is a bit
       weird because I am the svgalib maintainer and a working GGI  will  make
       svgalib obsolete. Again, I already said above: I did not invent svgalib
       nor do I promote it as the solution (now compare this to GGI). It  just
       does what it does and works for me and some other people.

       I  liked this idea so much, I even started coding a frame buffer device
       once. After a short time, other people came  out  with  the  GGI  idea.
       Right  from  their  beginning  they  claimed  to  be the only source of
       wisdom. I tried to join our efforts, but failed. In general we have the
       same goals (read the GGI project pages for that).

       Anyhow,  at  that  time a flame war started. I don’t really know why. I
       don’t see I did anything else  than  offering  my  opinions,  work  and
       experience. But that should be judged by others.

       Well,  after  some  time  I  stopped bothering them. I was satisfied to
       learn later though that they actually came up with some  conclusions  I
       proposed  first  but  weeks  or months later. But let us leave the past

       When intending to contribute to svgalib, you should  think  about  what
       you  really  want. I don’t see that GGI is becoming available soon. GGI
       people told me the opposite again and again, ok, I still don’t see  it.
       Still  out  of a sudden, everything might be GGI infested, so you might
       consider contributing to GGI instead.

       With svgalib you might be able to use your fruits earlier.  And  anyone
       (with   supported   hardware)  can  just  use  it  right  away  without
       reinstalling kernel/X11 what else (maybe being unable to use  something
       he did before).

   Q 8)
       Why not just use X11?

       Yes,  this  is  what many people say. This is the common Unix way to do
       it.  X does it.

       But X has some drawbacks:

       i)     It uses many resources. Admittedly this is  becoming  of  lesser
              importance now, where you can run a sensible X11 Linux system on
              8MB (16 MB for heaven like performance) which  is  the  absolute
              minimum to get a simple text editor running under M$ windows.

              Still,  an advantage of Linux is the ability to use old hardware
              for   mission   critical   background   jobs    on    the    net
              (servers/routers/firewalls)  on  low  price  or  otherwise  even
              unusable hardware.

       ii)    X has a nice API with draw commands for  any  kind  of  ’command
              oriented’  screen output. I mean with that: Select a color, draw
              a line, polygon, etc.

              This imposes a bunch of overhead. If you just want access to the
              screen memory, it slows things down as hell. If you want just to
              use above’s draw commands, it is ok!

       iii)   One can now circumvent the API restrictions  by  getting  direct
              screen  access  using a special Xfree extension. Basically Xfree
              just setups the screen and gives you shared memory access to the
              screen  memory. IMHO, this is not much different from the shared
              memory X11 extension by MIT (which is probably why it was  added
              so  easily).   Still it needs quite some overhead, at least when
              the card does not allow for a linear frame buffer.

              However, you cannot change screen modes and rez as easily.  This
              is  IMHO  THE  drawback of X. For a picture viewer, you want 256
              color high/true color modes on a per picture basis (also, insert
              any other application you like: movie viewers, a special game, a
              drawing program). Also, you want a small picture use a  low  rez
              s.t.  it  does  not  appear as a thumbnail, maybe use a high rez
              mode for a huge picture  which  you  don’t  want  to  use  on  a
              permanent  basis  because  it  flickers like hell (and you don’t
              want to use a panning virtual  desktop  too,  I  hated  them  at

              This  latter  restriction  can  of  course  be  circumvented  by
              enlarging the picture. But  this  will  need  much  time  for  a
              picture  viewer  already and certainly too much for smooth video
              or game animations.

       iv)    Finally, the problem how X11 itself accesses the screen  is  not
              solved.   Security is usually no concern because X11 does it, is
              a trusted executable and a firewall between applications and the

              Alas,  there  might  be  security  holes, also the stability and
              performance issues (IRQ driven accelerator  queue,  CPU  support
              for  VGA  memory  paging)  still exist, though one can expect an
              Xserver to be a generally well coded application.

   Q 9)
       Now, again, what about the future of svgalib?

       For console graphics, svgalib is  still  the  only  solution  for  most
       people,  and  as such it should go on for a while. Compared to the othe
       console graphics options (kgi and kernel fb  device),  writing  svgalib
       driver  is  the  simplest  (at least, this is my experience), and so it
       makes sense to believe that svgalib will work on all cards where  there
       is someone interested enough in that support.

   Q 10)
       Ok, just for completeness, what are your plans about svgalib anyway?

       First,  make  svgalib cooperate nicely with kernel fb device. Then (and
       it should be very similar) make svgalib work on a secondary vga card.

       A rewrite of the code for memory handling and virtual console  handling
       is  necessary  for the previous goals, but is also necessary in itself,
       and so will be done also.

       I do intend to maintain complete binary compatibility,  so  that  older
       programs will go on working.

       As  internal  changes are made, the drivers have to be changed as well.
       For some of the older drivers (ali, ark,  ati,  et3000,  et4000,  gvga,
       oak),  I no longer get any reports, so I don’t know if they still work.
       Some features are also lost, for example, linear frame buffer  on  non-
       PCI  cards.  This  should not be a very big problem, as users with such
       cards can go on using 1.3.1, as most changes  are  not  applicable  for
       older machines.


       svgalib(7), libvga.config(5).


       This file was written by Michael Weller <>,
       And later changed by Matan Ziv-Av.