It seems that this was a configuration problem that did not have any effect on earlier versions of Ubuntu. It disappeared after reinstalling GRUB2. It seems that the additional parameter "text" in the kernel arguments (see the line for "ProcKernelCmdLine" above) caused this problem on my system.
** Changed in: xorg (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1407991 Title: Xorg freeze Status in xorg package in Ubuntu: Invalid Bug description: After upgrading from Ubuntu 14.04 to Ubuntu 14.10, the system seems to hang during boot. I see the following screens: 1. GRUB boot menu 2. blank screen 3. a screen with output. This disappears quite fast so I was only able to read the first line which is "Restoring resolver state..." or something similar. 4. another screen with output. The last line of the output is "Starting upowerd...done." . After that, the system seems to hang. However, I'm still able to switch to another terminal via Alt+F2 and login there. If I use startx from there, a graphical environment starts. I'm not sure which one it is, but it does not seem to be XFCE which I'm normally using (I've configured XFCE to use a dark desktop theme: grey font on black background). This environment only has a background and some desktop icons. There is nothing else present, e.g. there are no bars. ProblemType: Bug DistroRelease: Ubuntu 14.10 Package: xorg 1:7.7+7ubuntu2 ProcVersionSignature: Ubuntu 3.16.0-28.38-generic 3.16.7-ckt1 Uname: Linux 3.16.0-28-generic x86_64 ApportVersion: 2.14.7-0ubuntu8 Architecture: amd64 CompizPlugins: [core,composite,opengl,compiztoolbox,decor,vpswitch,snap,mousepoll,resize,place,move,wall,grid,regex,imgpng,session,gnomecompat,animation,fade,workarounds,scale,expo,ezoom] Date: Tue Jan 6 10:04:44 2015 DistUpgraded: 2015-01-04 23:21:35,182 DEBUG enabling apt cron job DistroCodename: utopic DistroVariant: ubuntu ExtraDebuggingInterest: Yes, including running git bisection searches GpuHangFrequency: Continuously GpuHangReproducibility: Yes, I can easily reproduce it GpuHangStarted: Immediately after installing this version of Ubuntu GraphicsCard: Advanced Micro Devices, Inc. [AMD/ATI] RV515/M54 [Mobility Radeon X1400] [1002:7145] (prog-if 00 [VGA controller]) Subsystem: Lenovo Thinkpad T60 model 2007 [17aa:2006] MachineType: LENOVO 2007QPG PccardctlIdent: Socket 0: no product info available PccardctlStatus: Socket 0: no card ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.16.0-28-generic root=UUID=2a7cf7e8-4927-4e73-a6d3-e783efe97779 ro text quiet splash vt.handoff=7 SourcePackage: xorg Symptom: display Title: Xorg freeze UpgradeStatus: Upgraded to utopic on 2015-01-04 (1 days ago) dmi.bios.date: 09/12/2008 dmi.bios.vendor: LENOVO dmi.bios.version: 79ETE3WW (2.23 ) dmi.board.name: 2007QPG dmi.board.vendor: LENOVO dmi.board.version: Not Available dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: Not Available dmi.modalias: dmi:bvnLENOVO:bvr79ETE3WW(2.23):bd09/12/2008:svnLENOVO:pn2007QPG:pvrThinkPadT60:rvnLENOVO:rn2007QPG:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable: dmi.product.name: 2007QPG dmi.product.version: ThinkPad T60 dmi.sys.vendor: LENOVO version.compiz: compiz 1:0.9.12+14.10.20140918-0ubuntu1 version.ia32-libs: ia32-libs N/A version.libdrm2: libdrm2 2.4.56-1 version.libgl1-mesa-dri: libgl1-mesa-dri 10.3.0-0ubuntu3 version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A version.libgl1-mesa-glx: libgl1-mesa-glx 10.3.0-0ubuntu3 version.xserver-xorg-core: xserver-xorg-core 2:1.16.0-1ubuntu1.2 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.0-1ubuntu2 version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.4.0-2ubuntu2 version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.914-1~exp1ubuntu4.1 version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.11-1ubuntu2 xserver.bootTime: Mon Jan 5 10:12:04 2015 xserver.configfile: default xserver.errors: Server terminated successfully (0). Closing log file. xserver.logfile: /var/log/Xorg.0.log xserver.version: 2:1.16.0-1ubuntu1.2 xserver.video_driver: radeon To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1407991/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp