Bug reported by Harri Pitkänen in the Debian BTS today. He's trying to run a KDE4 development snapshot *within* Xephyr 1.4. It causes a crash with the following backtrace. The bug couldn't be reproduced with a stable KDE or Gnome. It's probably related to some Compositing stuff that KDE4 enables and I guess Xephyr does not support all of them yet... Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x2ba8310e7d30 (LWP 2510)] 0x000000000053080d in find_mesa_visual (screen=0xbf2350, vid=58) at ../../../GL/glx/glxglcore.c:290 290 return (modes != NULL) ? mesaScreen->xm_vis[i] : NULL; (gdb) bt full #0 0x000000000053080d in find_mesa_visual (screen=0xbd82e0, vid=58) at ../../../GL/glx/glxglcore.c:290 mesaScreen = (__GLXMESAscreen *) 0xbd82e0 modes = (const __GLcontextModes *) 0xd907f0 i = 0 #1 0x000000000053066a in __glXMesaScreenCreateContext (screen=0xbd82e0, modes=0xd907f0, baseShareContext=0x0) at ../../../GL/glx/glxglcore.c:237 context = (__GLXMESAcontext *) 0xda0350 shareContext = (__GLXMESAcontext *) 0x0 xm_vis = (XMesaVisual) 0x3a00000000 xm_share = (XMesaContext) 0xd907f0 #2 0x000000000054f883 in DoCreateContext (cl=0xd90730, gcId=12582918, shareList=0, visual=58, screen=0, isDirect=0 '\0') at ../../../GL/glx/glxcmds.c:206 client = (ClientPtr) 0xd92870 pVisual = (VisualPtr) 0xbed018 pScreen = (ScreenPtr) 0xd59f90 glxc = (__GLXcontext *) 0x8a4f60 shareglxc = (__GLXcontext *) 0x0 modes = (__GLcontextModes *) 0xd907f0 pGlxScreen = (__GLXscreen *) 0xbd82e0 i = 1 #3 0x000000000054f9c4 in __glXDisp_CreateContext (cl=0xd90730, pc=0xd9ff70 "\225\003\006") at ../../../GL/glx/glxcmds.c:249 req = (xGLXCreateContextReq *) 0xd9ff70 #4 0x0000000000530276 in __glXDispatch (client=0xd92870) at ../../../GL/glx/glxext.c:561 rendering = 0 '\0' stuff = (xGLXSingleReq *) 0xd9ff70 opcode = 3 '\003' proc = (__GLXdispatchSingleProcPtr) 0x54f96d <__glXDisp_CreateContext> cl = (__GLXclientState *) 0xd90730 retval = 0 #5 0x00000000004fabf5 in XaceCatchExtProc (client=0xd92870) at ../../Xext/xace.c:299 stuff = (xReq *) 0x0 major = 149 ext = (ExtensionEntry *) 0xbf21c0 #6 0x000000000046600f in Dispatch () at ../../dix/dispatch.c:502 clientReady = (int *) 0x7fff4168a710 result = 24 client = (ClientPtr) 0xd92870 nready = 0 icheck = (HWEventQueuePtr *) 0xbc1df0 start_tick = 2140 #7 0x000000000044a09f in main (argc=2, argv=0x7fff4168aca8, envp=0x7fff4168acc0) at ../../dix/main.c:452 i = 1 j = 2 k = 2 error = 1768139776 xauthfile = 0x0 alwaysCheckForInput = {0, 1} In case it matters, here are the latest KDE messages before the crash: kdeinit4: Got EXEC_NEW 'kwin' from launcher. kdeinit4: preparing to launch /home/kde/kde/bin/kwin klauncher(3750)/kio (KLauncher) KLauncher::processRequestReturn: "kwin" (pid 3764) up and running. kwin(3764) KWin::Extensions::init: Extensions: shape: 0x "11" composite: 0x "4" render: 0x "a" fixes: 0x "40" kwin(3764) KWin::CompositingPrefs::detect: glx version is 1 . 2
Okay, this is due to the fact that Xephyr actually does not provide any OpenGL renderer in 1.4.x. But as it was compiled with --enable-glx, the GLX extension was enabled, accepting GL requests. Those request could not be handled properly by the software GL renderer (mesa) because it was not initiliased. So Xephyr crashes. A proper possible solution is to disable the GLX extension for now. Xephyr in master will provide an accelerated GL renderer. So a I have pushed the fix 007e2239cf65535c4df3486e7b2cc42a4e86eb56 to fix the crach.
Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.