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Thread: is Xvfb colorblind?

  1. #1
    amhines NNTP User

    Default is Xvfb colorblind?

    I'm trying to run a graphical application in the background of a headless server for scientific work. But when I run Xvfb with basic values, it croaks if I attempt to access a shared or private colormap. What's up with that?!? Works perfectly if I ship it to a remote terminal, but that's not an option for what I need.
    Is there an argument that specifies the color depth or something? Running SLES 9/10, but don't think that should really matter.

  2. #2
    amhines NNTP User

    Default Re: is Xvfb colorblind?

    OK, I posted without enough info. I requested 8 bit color (WxHx8), but if I shoot some simple windows at my virtual display and grab the results with an xwd, every pixel is either black or white. If I try to display a color image, it either gives an X_StoreColors failure, or just plots solid black.

  3. #3
    amhines NNTP User

    Unhappy Re: is Xvfb colorblind?

    The plot thickens.
    When I run the same procesdure on a machine with a graphics head, it works perfectly.
    Here's my procedure:

    > Xvfb :3 -ac -screen 1 1024x768x8 +bs -fbdir /tmp &
    > setenv DISPLAY :3
    > xv pretty_pix.jpg &
    > xwd -display :3 -root -out window_1.xwd

    So on one machine it gives me the expected desktop image. On the headless machine, I get an image of a solid black window on an empty desktop. Or, if I try another application,using a private colormap, it gives an error:

    X Error of failed request: BadAccess (attempt to access private resource denied)
    Major opcode of failed request: 89 (X_StoreColors)
    Serial number of failed request: 2061
    Current serial number in output stream: 3227

    Any takers?

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