Public bug reported: I'm not sure what's the root of the problem. But when I write SDL programs and forget SwapBuffers I only get a black window, and the system locks up: mouse remains responsive but keyboard dies (pressing lock keys does not cause the led switch). The only way to resume work is a hard reset.
Of course forgetting swapBuffers is obviously my mistake, but the consequences are quite annoying. Minimal source code the reproduce it: #include <stdio.h> #include <SDL/SDL.h> #include <GL/gl.h> #define SCREEN_WIDTH 800 #define SCREEN_HEIGHT 600 void drawStuff() { glClearColor(0, 0, 1, 0); glClear(GL_COLOR_BUFFER_BIT); /* Without this the system locks up. */ /* SDL_GL_SwapBuffers(); */ } int main() { SDL_Surface *screen; SDL_Event event; SDL_Init(SDL_INIT_EVERYTHING); atexit(SDL_Quit); SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 ); screen = SDL_SetVideoMode(SCREEN_WIDTH, SCREEN_HEIGHT, 32, SDL_OPENGL); for(;;) { drawStuff(); while (SDL_PollEvent(&event)) { switch (event.type) { case SDL_QUIT: goto exitLoop; } } } exitLoop: SDL_FreeSurface(screen); return 0; } ProblemType: Bug DistroRelease: Ubuntu 12.04 Package: xorg 1:7.6+12ubuntu2 ProcVersionSignature: Ubuntu 3.2.0-57.87-generic 3.2.52 Uname: Linux 3.2.0-57-generic x86_64 .tmp.unity.support.test.0: ApportVersion: 2.0.1-0ubuntu17.6 Architecture: amd64 CompizPlugins: [core,composite,opengl,compiztoolbox,decor,vpswitch,snap,mousepoll,resize,place,move,wall,grid,regex,imgpng,session,gnomecompat,animation,fade,unitymtgrabhandles,workarounds,scale,expo,ezoom,unityshell] CompositorRunning: None Date: Wed Dec 4 09:11:01 2013 DistUpgraded: 2013-05-12 13:21:09,910 DEBUG enabling apt cron job DistroCodename: precise DistroVariant: ubuntu DkmsStatus: vboxhost, 4.3.4, 3.2.0-56-generic, x86_64: installed vboxhost, 4.3.4, 3.2.0-57-generic, x86_64: installed ExtraDebuggingInterest: Yes, if not too technical GpuHangFrequency: This is the first time GpuHangReproducibility: Yes, I can easily reproduce it GpuHangStarted: Today GraphicsCard: Intel Corporation 4 Series Chipset Integrated Graphics Controller [8086:2e12] (rev 03) (prog-if 00 [VGA controller]) Subsystem: Hewlett-Packard Company Device [103c:3034] Subsystem: Hewlett-Packard Company Device [103c:3034] InstallationMedia: Ubuntu 10.04.4 LTS "Lucid Lynx" - Release amd64 (20120214.2) MachineType: Hewlett-Packard HP Compaq dc7900 Small Form Factor MarkForUpload: True ProcEnviron: TERM=xterm PATH=(custom, no user) LANG=hu_HU.UTF-8 SHELL=/bin/bash ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-57-generic root=UUID=be6a77fe-88c7-4689-a680-51684e19672d ro quiet splash vt.handoff=7 SourcePackage: xorg Symptom: display Title: Xorg freeze UpgradeStatus: Upgraded to precise on 2013-05-12 (205 days ago) dmi.bios.date: 03/05/2009 dmi.bios.vendor: Hewlett-Packard dmi.bios.version: 786G1 v01.16 dmi.board.asset.tag: CZC9331R6C dmi.board.name: 3031h dmi.board.vendor: Hewlett-Packard dmi.chassis.asset.tag: CZC9331R6C dmi.chassis.type: 4 dmi.chassis.vendor: Hewlett-Packard dmi.modalias: dmi:bvnHewlett-Packard:bvr786G1v01.16:bd03/05/2009:svnHewlett-Packard:pnHPCompaqdc7900SmallFormFactor:pvr:rvnHewlett-Packard:rn3031h:rvr:cvnHewlett-Packard:ct4:cvr: dmi.product.name: HP Compaq dc7900 Small Form Factor dmi.sys.vendor: Hewlett-Packard version.compiz: compiz 1:0.9.7.12-0ubuntu3 version.ia32-libs: ia32-libs 20090808ubuntu36 version.libdrm2: libdrm2 2.4.43-0ubuntu0.0.3 version.libgl1-mesa-dri: libgl1-mesa-dri 8.0.4-0ubuntu0.6 version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A version.libgl1-mesa-glx: libgl1-mesa-glx 8.0.4-0ubuntu0.6 version.xserver-xorg-core: xserver-xorg-core 2:1.11.4-0ubuntu10.14 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.7.0-0ubuntu1.2 version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.99~git20111219.aacbd629-0ubuntu2 version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.17.0-1ubuntu4.4 version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20111201+b5534a1-1build3 ** Affects: xorg (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug freeze precise ubuntu -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1257632 Title: A forgotten SDL_GL_SwapBuffers can cause system freeze To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1257632/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs