My work around is:
keep my PC on top of a work table beside my workstation to facilitate video card switching.. to remove it and install an AMD Radeon HD5450 which will boot and switch to nouveau with the new hardware discovery. Older boot attempts in the syslog file indicate to my limited view the Nvidia driver has no authority to access it's own files after kernel update an hour and a half ago. The root cause.. not really Xorg, ...go figure. Before the update I was thinking.. should I switch to nouveau for the update. Nahhh they fixed that nvidia driver kernel bug. It actually was for a while.
Ubuntu 14.04
Nvidia GTX 460, old iron.
ASRock Fata1ity amd mobo, this also used to happen on my gigabyte board over the last year and a half.
email me if you didn't get the syslog.
ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: xorg 1:7.7+1ubuntu8.1
ProcVersionSignature: Ubuntu 3.13.0-70.113-generic 3.13.11-ckt29
Uname: Linux 3.13.0-70-generic x86_64
.tmp.unity.support.test.0:
ApportVersion: 2.14.1-0ubuntu3.19
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Tue Dec 1 12:05:03 2015
DistUpgraded: Fresh install
DistroCodename: trusty
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, if not too technical
GpuHangFrequency: Continuously
GpuHangReproducibility: Yes, I can easily reproduce it
GpuHangStarted: Today
GraphicsCard:
Advanced Micro Devices, Inc. [AMD/ATI] Caicos [Radeon HD 6450/7450/8450 / R5 230 OEM] [1002:6779] (prog-if 00 [VGA controller])
Subsystem: PC Partner Limited / Sapphire Technology Device [174b:a007]
InstallationDate: Installed on 2014-11-23 (373 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
MachineType: To Be Filled By O.E.M. To Be Filled By O.E.M.
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-70-generic root=UUID=0d38073f-c972-4a45-8c1e-db6c24cb8537 ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
Title: Xorg freeze
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 08/04/2015
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: P1.50
dmi.board.name: 990FX Killer
dmi.board.vendor: ASRock
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP1.50:bd08/04/2015:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASRock:rn990FXKiller:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
dmi.product.name: To Be Filled By O.E.M.
dmi.product.version: To Be Filled By O.E.M.
dmi.sys.vendor: To Be Filled By O.E.M.
version.compiz: compiz 1:0.9.11.3+14.04.20150313-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.60-2~ubuntu14.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 10.1.3-0ubuntu0.5
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 10.1.3-0ubuntu0.5
version.xserver-xorg-core: xserver-xorg-core 2:1.15.1-0ubuntu2.7
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.8.2-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.3.0-1ubuntu3.1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.910-0ubuntu1.6
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.10-1ubuntu2
xserver.bootTime: Tue Dec 1 11:39:31 2015
xserver.configfile: default
xserver.errors:
xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.15.1-0ubuntu2.7
xserver.video_driver: radeon
ERv Bendiks, thank you for reporting this and helping make Ubuntu better.
Would upgrading to the Vivid enablement stack help here following https:/