Re: [Xmonad] Xinerama

12 Jun 2007

      On Wed, 13 Jun 2007 00:33:10 +1000
Aldo Cortesi  wrote:
...
Hi folks,
I'm seeing symptoms similar to the the same Xinerama-related problem
reported here:
http://www.haskell.org/pipermail/xmonad/2007-June/000491.html
In that same thread, Jason Creighton suggested running the following
test script:
"""
    import Graphics.X11.Xlib
    import Graphics.X11.Xinerama
main = do
        d <- openDisplay ""
        xineramaQueryScreens d >>= print
        getScreenInfo d >>= print
"""
On my system, this outputs:
"""
Nothing
[Rectangle {rect_x = 0, rect_y = 0, rect_width = 1920, rect_height =
1200}] """
Now the plot thickens. The following snippet of C should be very
nearly equivalent to the script above:
"""
#include 
#include 
#include 
#include 
#include 
int main (){
    Display *dpy;
    XineramaScreenInfo *xsi;
    int i, num;
    dpy = XOpenDisplay("\0");
    printf("%s\n", XDisplayString(dpy));
    if((xsi = XineramaQueryScreens(dpy, &num))) {
        printf("%i screens\n", num);
        for(i = 0; i < num; i++) {
           printf("%i: %ix%i\n", xsi[i].screen_number, xsi[i].width,
xsi[i].height); }
       XFree(xsi);
    }
    XCloseDisplay(dpy);
    return 0;
}
"""
However, from this, I get the following output:
2 screens
0: 1920x1200
1: 1280x1024
As you can see, the Xinerama screens are detected correctly. Xinerama
under other window managers (e.g. KDE) also seems to work flawlessly
with the same X configuration. Despite this is being my first real
foray into Haskell, I bravely ploughed through the appropriate
bindings in X11-extras and X11-1.2.2, but I could see no obvious
errors.
I have a hunch that the problem is related to the fact that I have an
NVidia graphics card with TwinView (NVidia's magic sauce that allows
you to connect multiple screens to the same GPU). Apparently,
Twinview is known to cause problems with some window managers - see,
for example, the FAQ section of this page from NVidia:
http://http.download.nvidia.com/XFree86/Linux-x86/1.0-8178/README/appendix-g...
The FAQ entry is pretty vague about exactly what form these
"problems" might take.
I'm keen to give XMonad a try, so I'd be happy to spend time helping
to troubleshoot this problem...
Cheers,
Aldo
Are you running X11-extras from darcs?  If so, did you run 'autoreconf'
before running 'Setup configure'? (this step isn't required if you're
compiling from a release tarball)

Watch X11-extras configure output for:
checking X11/extensions/Xinerama.h usability... yes
checking X11/extensions/Xinerama.h presence... yes
checking for X11/extensions/Xinerama.h... yes

Hope that helps,
Spencer Janssen