Direct access to the video card

Direct access to the video card

Post by Akita Bright-Hollowa » Sun, 25 Feb 2001 14:19:47



Okie, first off im using FreeBSD, and i have a tnt2 in my computer, so, i
was thinking about trying to play with direct access to the video card,
back in the dos days all we had to do is throw out a couple lines of
assembly and start writting to 0xa0000000 but i imagine its a little more
involved than that for unix, or is it ? i havnt been able to find any
documentation on anything to do with talking directly to the video card,
but im sure its out there, anyone have any links ? anyone know how to
start talking to the video card ? Thanks in advance !

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Direct access to the video card

Post by Jens.Toerr.. » Mon, 26 Feb 2001 05:37:07



> Okie, first off im using FreeBSD, and i have a tnt2 in my computer, so, i
> was thinking about trying to play with direct access to the video card,
> back in the dos days all we had to do is throw out a couple lines of
> assembly and start writting to 0xa0000000 but i imagine its a little more
> involved than that for unix, or is it ? i havnt been able to find any
> documentation on anything to do with talking directly to the video card,
> but im sure its out there, anyone have any links ? anyone know how to
> start talking to the video card ? Thanks in advance !

Actually, it's a lot different from DOS! The main difference is that
72is a single user, single tasking system while UN*X is a multi-user,
multi-tasking system. So, you always have to assume, that there isn't
just one process that's drawing to the screen but many and there has to
be some controlling instance, that gets asked by the different programs
to draw something and decides when and where this is done. So, no simple
program should be able to access the graphics hardware (or any hardware
at all) directly but only via requesting a service from the controlling
instance. Often, this controlling instance is the kernel (or a module
that gets loaded into the kernel). For grapics, it's the X server
probably running on your machine.

Of course, you can start hacking X or not use X at all and do everything
using your own routines (which must probably ask the kernel nicely to
allow it ;-) But that may not be what you want do, so the short answer
to your question probably is, you can't simply access your graphics card
as you did in DOS.
                                                  Jens
--
        _  _____  _____

    _  | |  | |    | |           AG Moebius, Institut fuer Molekuelphysik
   | |_| |  | |    | |           Fachbereich Physik, Freie Universitaet Berlin
    \___/ens|_|homs|_|oerring    Tel: ++49 (0)30 838 - 53394 / FAX: - 56046

 
 
 

Direct access to the video card

Post by Akita Bright-Hollowa » Sun, 25 Feb 2001 16:02:42




> Of course, you can start hacking X or not use X at all and do everything
> using your own routines

Thats what im interested in :) This is more for my own personal
programming benifit, i havnt made kernel modules yet, nor have i started
to hack X, and i would really rather like to, same with writting drivers,
i really dont know what im doing, and it would probabbly be a good idea
to start learning some here, so if you have any links or any info on
writting kernel modules, drivers, and or talkin nice to the kernel to let
me play directly with the video card, that would be pretty cool :) Thanks
in advance again!

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Direct access to the video card

Post by Michael Pow » Tue, 27 Feb 2001 05:17:24




    >> Of course, you can start hacking X or not use X at all and do
    >> everything using your own routines

    Akita> Thats what im interested in :) This is more for my own
    Akita> personal programming benifit, i havnt made kernel modules
    Akita> yet, nor have i started to hack X, and i would really
    Akita> rather like to, same with writting drivers, i really dont
    Akita> know what im doing, and it would probabbly be a good idea
    Akita> to start learning some here, so if you have any links or
    Akita> any info on writting kernel modules, drivers, and or talkin
    Akita> nice to the kernel to let me play directly with the video
    Akita> card, that would be pretty cool :) Thanks in advance again!

In linux, you can use SVGAlib.  I don't know if there's anything like
it for FreeBSD, but you could look at their website.  Or ask them.

mp

--
    -----------Michael Powe         Portland, Oregon USA----------
"There are 100,000 total * smokers in the U.S., and most are
Negroes, Hispanics, Filipinos and entertainers.  Their Satanic music,
jazz and swing, result from * use.  This * can cause
white women to seek * relations with Negroes, entertainers and
any others."  -- Harry J. Anslinger, Dir. Fed. Bureau of Narcotics,
Congressional Testimony, 1937

 
 
 

Direct access to the video card

Post by Torbjorn Tallro » Mon, 05 Mar 2001 04:43:23



Quote:> In linux, you can use SVGAlib.  I don't know if there's anything like
> it for FreeBSD, but you could look at their website.  Or ask them.

FreeBSD has vgl(3) since version 3.0.

I guess one could mmap(2) /dev/mem, starting at offset 0xA0000 to
access video memory directly and do card initialization in assembler
through the I/O ports.

/Torbj?rn