This does not appear to be exclusive to the nouveau or xorg. I've been able to reproduce it at the console by plugging in display port without X11 running.
I open htop, everything looks fine. Then I plug in the display port cable and the CPU immediately shoots up to 100%. I've also loaded the intel driver (rebooting into macOS, selecting integrated driver and confirming it is running with vga_switcheroo once i reboot back into linux), and i get the exact same behavior. Note, booting with the displayport cable attached will cause the system to hang during initialization, I guess because the kworker takes 100% of the CPU. I've also had this happen with the proprietary nvidia driver loaded. This doesn't seem to have anything to do with the graphics driver, but rather the kernel itself is having a hard time with the thunderbolt port managing the display port connection. Oddly enough, this issue doesn't happen 100% of the time for me. I've had days where it didn't happen at all, and days where it is non stop. I'm running out of ideas on debugging this one, other than that the problem is almost certainly in the kernel itself, and is probably related to sketchy thunderbolt support since this never happens with just normal HDMI output. Hide comment -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to xserver-xorg-video-nouveau in Ubuntu. https://bugs.launchpad.net/bugs/1020221 Title: [Lenovo ThinkPad T510] Connecting an external Monitor over DisplayPort freezes the screen Status in “xserver-xorg-video-nouveau” package in Ubuntu: Incomplete Bug description: When I plug in a second Monitor using a DisplayPort cable, the system becomes barely responsive (all you can do is move the mouse very slow) and [kworker/1:2] is using 100% CPU in top. A few seconds after pulling the cable out the system works normally again. Filing this against the driver and not the kernel as the nvidia driver works somewhat fine. ProblemType: BugDistroRelease: Ubuntu 12.10 Package: xserver-xorg-video-nouveau 1:1.0.1-1build1 ProcVersionSignature: Ubuntu 3.5.0-2.2-generic 3.5.0-rc4 Uname: Linux 3.5.0-2-generic x86_64 ApportVersion: 2.2.5-0ubuntu1 Architecture: amd64 CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins' CompositorRunning: kwin Date: Mon Jul 2 19:31:07 2012 DistUpgraded: Fresh install DistroCodename: quantal DistroVariant: kubuntu ExtraDebuggingInterest: Yes, whatever it takes to get this fixed in Ubuntu GraphicsCard: NVIDIA Corporation GT218 [NVS 3100M] [10de:0a6c] (rev a2) (prog-if 00 [VGA controller]) Subsystem: Lenovo Device [17aa:215c] InstallationMedia: Kubuntu 11.10 "Oneiric Ocelot" - Beta amd64 (20111007) MachineType: LENOVO 4349W1R ProcEnviron: SHELL=/bin/bash TERM=screen PATH=(custom, user) LANG=en_US.UTF-8 LANGUAGE=en_US.UTF-8 ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-3.5.0-2-generic root=UUID=238190c9-6304-41fe-892a-28596720e11b ro rootflags=subvol=@SourcePackage: xserver-xorg-video-nouveau UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 10/26/2010 dmi.bios.vendor: LENOVO dmi.bios.version: 6MET81WW (1.41 ) dmi.board.name: 4349W1R 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:bvr6MET81WW(1.41):bd10/26/2010:svnLENOVO:pn4349W1R:pvrThinkPadT510:rvnLENOVO:rn4349W1R:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable: dmi.product.name: 4349W1R dmi.product.version: ThinkPad T510 dmi.sys.vendor: LENOVO version.compiz: compiz N/A version.ia32-libs: ia32-libs 20090808ubuntu36 version.libdrm2: libdrm2 2.4.33-3 version.libgl1-mesa-dri: libgl1-mesa-dri 8.0.3-0ubuntu1 version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A version.libgl1-mesa-glx: libgl1-mesa-glx 8.0.3-0ubuntu1 version.xserver-xorg-core: xserver-xorg-core 2:1.12.1.902-1ubuntu1 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.7.0-0ubuntu2 version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.99~really6.14.4-0ubuntu2 version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.19.0-1ubuntu2 version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.1-1build1 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-nouveau/+bug/1020221/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
