Xdmx segfaults when calling GetWindowPixmap

8yRgR4DKpg6w at dyweni.com 8yRgR4DKpg6w at dyweni.com
Fri Feb 13 12:34:29 PST 2009

Hi List,

I'd like to know if anyone has ran across this.

I've upgraded to X.Org 7.4 (Xorg-server 1.5.3) on Gentoo.

I'm starting Xdmx with this command:
 Xdmx :1 -display machinea:0 machineb:0 -input machinea:0 +xinerama

I then try to display a simple xterm and that causes Xdmx to seg fault.

The fault occurs in:
 File:  mi/miexpose.c
 Line:  591 "draw_x_off = pixmap->screen_x;"
 Function: miPaintWindow

On line 588, it reads:
  pixmap = (*pScreen->GetWindowPixmap) ((WindowPtr) drawable)

For what I can tell, pixmap is not initialized correctly.

GetWindowPixmap calls function _fbGetWindowPixmap,
  which calls macro fbGetWindowPixmap,
  which calls functions fbGetWinPrivateKey and dixLookupPrivate.

dixLookupPrivate then calls function dixAllocatePrivate

dixAllocatePrivate returns a pointer to 0x82b2374,
  which contains 0x0

The 0x0 is the problem I believe, as pixmap is then defined as 0x0
and thus causes the segfault.

If I tell miPaintWindow to return after calling GetWindowPixmap,
then the program does not crash and xterm displays correctly


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