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Using X and SVGAlib Concurrently?

Posted by Cliff on from the another-way-to-multi-head dept.

Walter Bell asks: "I have two video cards in my Linux PC, one of which has a TV out jack. I would like to connect the TV out jack to my color LCD panel and use it as a system status monitor (kind of like this), while I am running X on the other video card to serve as my desktop. Is it possible to use SVGAlib/GGI and X at the same time on two different video adapters? Right now I can switch between the two but only one of the adapters is active at a given time, depending on which virtual console is active. Is there a workaround?"

12 comments

  1. Two instances of X by tigersha · · Score: 1

    On another note, is it possible to run two instances of X on the same machine with 2 videocards? I would like to use a USB keyboard/mouse on one screen and the normal PS2/ stuff on the other. And I particularly want to run 2 instances of xdm/gsm/kdm/your-favourite-dm.

    The reason is that my GF sometimes wants to read her mail while I am working and this cannot possibly be such a CPU drain (I have a GB of RAM, after all).

    Any ideas?

    L

    --
    The dangers of excessive individualism are nothing compared to the oppressiveness of excessive collectivism
    1. Re:Two instances of X by nneul · · Score: 2

      Running two instances of X is not a problem. I do it regularly to run certain apps under wine, and for dvd playback to TV. What you can't do is output from more than one simultaneously, or at least I have not seen any way to do it.

    2. Re:Two instances of X by Walter+Bell · · Score: 2, Interesting

      That's the same kind of problem I ran into. You can have svgalib and X active at the same time, but only one has control of the console and only one video card gets output.

      I considered running two X instances (like what you want to do) but most TV out cards are less than friendly to X because of Macrovision "trade secrets." For my application, svgalib at 320x200 would be more than adequate and it will still work with TV out.

      I was considering hacking svgalib so that I can run it from within an xterm (currently it complains that it can't open the VGA console and dies), so that it issues the int10 calls to the video BIOS on the first card while the Xserver video card is unaffected. But I strongly suspect that this will cause a big problem if X dies or I otherwise need to switch virtual consoles, because the kernel will have no idea what state the video cards are in.

      Any ideas....? It *should* be doable.

      ~wally

    3. Re:Two instances of X by nneul · · Score: 2

      Seems to me that the problem is that X on linux is very much tied to a vty. If you could get X to run independent of a VTY, then it would work.

      i.e. linux can only have one vty active at a time - so only one X/TTY/SVGA output at a time.

    4. Re:Two instances of X by BJH · · Score: 1

      Buy a cheapo PC and hook the two together with a cheapo hub and some Cat5. No worrying about two X servers running on sepearate video cards, no worrying about two separate input devices...

    5. Re:Two instances of X by Anonymous Coward · · Score: 0

      Get a multihead X Server.

      Problem solved.

  2. YES YOU CAN HAVE 2 INSTANCES OF X... by Anonymous Coward · · Score: 0

    Well there is a hack i have running at home that i found on google...

    I have a geforce2 ultra outputting to its tv-out
    and i have a voodoo2 for a desktop...

    That way my wife can play games while I get work done...

    http://cambuca.ldhs.cetuc.puc-rio.br/multiuser/

    a few people reported that they were able to get this hack to work with an s3 virge...

    but I was only able to get it to work with a voodoo and a voodoo2 as the secondary...

    - r0gu3 at subspace dot net

  3. Are you approaching the problem right? by cr0sh · · Score: 2

    The reason I ask is because you essentially want to convert a VGA signal, to a TV signal, then show that on an LCD panel. You have a lot of conversion going on there, and all to display what? Stats for the system?

    Perhaps you could display some large text, or perhaps some largish bar graphs - but output in the manner you are wanting to do this is going to look very "fuzzy" - this is fine for games and video (ie, stuff that moves a bit) - but it isn't what you want for a text display - or at least a "clean" display.

    If all you want are stats - save the LCD panel for another project. Drop the second card (unless you are using it for something), and add a simple LCD display via the parallel port, and run LCDPROC. A couple of cheap pushbuttons and some port monitoring and you can easily add page up/down capabilities from the case. I can't really see the need to do what you are planning, unless you are planning on running fancy screensavers or something on the box when it isn't displaying stats or whatnot...

    --
    Reason is the Path to God - Anon
    1. Re:Are you approaching the problem right? by Walter+Bell · · Score: 1

      Well, the video card does have TV out, so I'm guessing that it produces NTSC and VGA concurrently rather than sequentially?

      I have experimented with outputting text. It is surprisingly clear, as long as I stick to (say) 30x10. But that wasn't my concern - the big hurdle was getting svgalib to work on an inactive vidcard. I figured I could put up some snazzy graphs that would offset the fuzzy text.

      But I probably am going to have to go the character LCD route. I have an old 4x20 HD44780 based LCD that I can hook up to an EDE702 and then to a serial port. Same as a Matrix Orbital but half the cost. Color and graphics would have been nice tho..

      My only big problem with that is that the EL backlight burned out. Any ideas on how to replace those suckers?

      ~wally

    2. Re:Are you approaching the problem right? by cr0sh · · Score: 2

      Not necessarily. It depends on the "quality" of the video card. Some video cards will allow this, others require that you switch to a special "tweaked" settings mode to get TV-out, while still others have special routing circuitry that is set by a register on the card (or via some wierd I2C bus control). Here are some sites that might help:

      VGA to TV Information Center
      Chrontel
      Video Timing Calculator
      VGATV Homepage

      As far as the LCD module is concerned - the EDE702 is a good choice - I would almost say with it and the LCD it would be 1/3 the cost of the Matrix Orbital (of course, what you are kinda paying on the MO device is the nice repackaging to make everything fit in a small area). As far as the EL backlight burnout: it might be possible to replace it - but I am not sure it would be worth the trouble. You can get EL kits from AllElectronics, that could be cut and adapted for the device - then you would have to take the LCD off the board and replace the EL portion (if the LCD is truely seperate - otherwise you would be taking the LCD apart - you may or may not get it back together again where it works properly).

      I would go to EIO or AllElectronics and buy another display, personally.

      --
      Reason is the Path to God - Anon