The pattern of corruption looks like a pixel format mixup or colour channel overflow. So I would bet it's related to the 10-bit/8-bit colour changes in Mesa and Mutter...
I can't reproduce it on my desktop (Haswell, 10-bit monitor). I can reproduce it on two laptops (Kaby Lake, 8-bit panels). Is the problem Ubuntu-specific? I've been wondering if our mesa patch(es) in this area are still necessary (since mutter fixed their side, didn't they?). ** Also affects: xorg-server (Ubuntu) Importance: Undecided Status: New ** Changed in: xorg-server (Ubuntu) Status: New => Confirmed ** Tags added: visual-quality ** Changed in: gnome-shell (Ubuntu) Importance: Undecided => Medium ** Changed in: mesa (Ubuntu) Importance: Undecided => Medium ** Changed in: mesa (Ubuntu) Status: Incomplete => Confirmed ** Changed in: mutter (Ubuntu) Importance: Undecided => Medium ** Changed in: xorg-server (Ubuntu) Importance: Undecided => Medium -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to mesa in Ubuntu. https://bugs.launchpad.net/bugs/1753776 Title: Graphics corruption (or distortion?) in login animation to Xorg sessions Status in gnome-shell package in Ubuntu: Confirmed Status in mesa package in Ubuntu: Confirmed Status in mutter package in Ubuntu: Confirmed Status in xorg-server package in Ubuntu: Confirmed Bug description: Immediately after login (I enter the password and hit enter) the screen "crumbles" for few seconds, then all becomes normal and the system works fine. I have done apt update+upgrade many times, also with proposed enabled, I have also installed a new ISO (now i'm using the Alpha dated 20180305) but the problem remains. The problem happens with the x11 session but not with wayland. Also problem does not show with different hardware. corrado@corrado-p7-bb-0305:~$ inxi -Fx System: Host: corrado-p7-bb-0305 Kernel: 4.15.0-10-generic x86_64 bits: 64 gcc: 7.3.0 Desktop: Gnome 3.27.92 (Gtk 3.22.28-1ubuntu3) Distro: Ubuntu Bionic Beaver (development branch) Machine: Device: desktop Mobo: ASRock model: H110M-G/M.2 serial: N/A UEFI: American Megatrends v: P1.10 date: 05/11/2017 CPU: Dual core Intel Core i3-7100 (-MT-MCP-) arch: Skylake rev.9 cache: 3072 KB flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 15648 clock speeds: max: 3900 MHz 1: 1018 MHz 2: 3150 MHz 3: 3153 MHz 4: 3081 MHz Graphics: Card: Intel HD Graphics 630 bus-ID: 00:02.0 Display Server: x11 (X.Org 1.19.6 ) driver: i915 Resolution: 1920x1080@60.00hz OpenGL: renderer: Mesa DRI Intel HD Graphics 630 (Kaby Lake GT2) version: 4.5 Mesa 18.0.0-rc4 Direct Render: Yes Audio: Card Intel Sunrise Point-H HD Audio driver: snd_hda_intel bus-ID: 00:1f.3 Sound: Advanced Linux Sound Architecture v: k4.15.0-10-generic Network: Card: Intel Ethernet Connection (2) I219-V driver: e1000e v: 3.2.6-k bus-ID: 00:1f.6 IF: enp0s31f6 state: up speed: 100 Mbps duplex: full mac: 70:85:c2:44:7b:86 Drives: HDD Total Size: 1000.2GB (1.3% used) ID-1: /dev/sda model: TOSHIBA_DT01ACA1 size: 1000.2GB Partition: ID-1: / size: 32G used: 4.3G (15%) fs: ext4 dev: /dev/sda7 ID-2: swap-1 size: 8.59GB used: 0.00GB (0%) fs: swap dev: /dev/sda2 RAID: No RAID devices: /proc/mdstat, md_mod kernel module present Sensors: System Temperatures: cpu: 38.5C mobo: N/A Fan Speeds (in rpm): cpu: N/A Info: Processes: 234 Uptime: 11 min Memory: 1144.7/7680.8MB Init: systemd runlevel: 5 Gcc sys: N/A Client: Shell (bash 4.4.181) inxi: 2.3.56 corrado@corrado-p7-bb-0305:~$ ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: xorg 1:7.7+19ubuntu5 ProcVersionSignature: Ubuntu 4.15.0-10.11-generic 4.15.3 Uname: Linux 4.15.0-10-generic x86_64 ApportVersion: 2.20.8-0ubuntu10 Architecture: amd64 BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log' CompositorRunning: None CurrentDesktop: ubuntu:GNOME Date: Tue Mar 6 15:47:50 2018 DistUpgraded: Fresh install DistroCodename: bionic DistroVariant: ubuntu ExtraDebuggingInterest: Yes, if not too technical GraphicsCard: Intel Corporation HD Graphics 630 [8086:5912] (rev 04) (prog-if 00 [VGA controller]) Subsystem: ASRock Incorporation HD Graphics 630 [1849:5912] InstallationDate: Installed on 2018-03-05 (0 days ago) InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Alpha amd64 (20180305) Lsusb: Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 003: ID 046d:c016 Logitech, Inc. Optical Wheel Mouse Bus 001 Device 002: ID 058f:6377 Alcor Micro Corp. AU6375 4-LUN card reader Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub MachineType: To Be Filled By O.E.M. To Be Filled By O.E.M. ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-10-generic.efi.signed root=UUID=9a36b498-59f5-4a36-81db-3046ff6bdeaa ro quiet splash SourcePackage: xorg Symptom: display UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 05/11/2017 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: P1.10 dmi.board.name: H110M-G/M.2 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.:bvrP1.10:bd05/11/2017:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASRock:rnH110M-G/M.2:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.: dmi.product.family: To Be Filled By O.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 N/A version.libdrm2: libdrm2 2.4.90-1 version.libgl1-mesa-dri: libgl1-mesa-dri 18.0.0~rc4-1ubuntu3 version.libgl1-mesa-glx: libgl1-mesa-glx 18.0.0~rc4-1ubuntu3 version.xserver-xorg-core: xserver-xorg-core 2:1.19.6-1ubuntu2 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.10.0-1 version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20171229-1 version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.15-2 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1753776/+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