SvgaLib/doc/man7/svgalib.faq.7

.TH svgalib.faq 7 "10 Jun 1999" "Svgalib 1.4.1" "Svgalib User Manual"
.SH NAME
svgalib.faq \- frequently asked questions about svgalib

.SH INTRODUCTION
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 <eowmob@exp-math.uni-essen.de>. I'd like
this to change. So email your suggestion (best of all: question and the
answer).

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 me.

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

.SH CONTENTS
.TP
.B Q 1)
I want to write some svgalib application. Where is the documentation?
.TP
.B Q 2)
My board is not supported. What now?
.TP
.B Q 3)
I get:

.B You must be the owner of the current console to use svgalib.
.br
.B 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.
.TP
.B Q 4)
Is svgalib dead?
.TP
.B Q 5)
There are so many Xfree drivers, why not just use them.
.TP
.B Q 6)
Why not just use the VGA BIOS?.
.TP
.B Q 7)
What about GGI?
.TP
.B Q 8)
Why not just use X11?
.TP
.B Q 9)
Now, again, what about the future of svgalib?
.TP
.B Q 10)
Ok, just for completeness, what are your plans about svgalib anyway?
.TP
.B Q 11)
Nice plan. But will it become true?
.PP

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

.SS A a)
Well, did you really look at everything? The
.I 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
.I demos/ subdir. They should
get you started.

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

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

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

.SS A)
Simple:

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

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

.TP
.B 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!).
.PP

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).

.SS Q 3)
I get:

.B You must be the owner of the current console to use svgalib.
.br
.B 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.

.SS A)
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
.B ROOT_VC_SHORTCUT
in
.I 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.
     
.SS Q 4)
Is svgalib dead?

.SS A)
This question comes up frequently esp. in recent times.

The answer is, of course, no.

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

.SS A)
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.

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

.SS A)
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. 

.SS Q 7)
What about GGI?

.SS A)
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
.B 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 alone.

.PP
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).

.SS 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:

.IP 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.

.IP 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!

.IP 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 best).

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.

.IP 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 hardware.

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.

.SS 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 other 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.

.SS 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 similiar) 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. 

.SH SEE ALSO
.BR svgalib (7),
.BR libvga.config (5).

.SH AUTHOR
This file was written by Michael Weller <eowmob@exp-math.uni-essen.de>,
And later changed by Matan Ziv-Av.