Jarkko, Forgot to mention that you at least need to install 3 packages if you want to try the test kernel. linux-image-unsigned-6.8.0-99-generic_6.8.0-99.99_amd64.deb linux-modules-6.8.0-99-generic_6.8.0-99.99_amd64.deb linux-modules-extra-6.8.0-99-generic_6.8.0-99.99_amd64.deb
** Description changed: + SRU Justification + + [Impact] + Systems with Intel CoffeeLake (CFL) and WhiskeyLake (WHL) integrated graphics experience screen flickering issues when running Ubuntu kernel 6.8.0-x. + + The issue occurs because: + 1. Ubuntu kernel configuration enables CONFIG_INTEL_IOMMU_DEFAULT_ON and CONFIG_INTEL_IOMMU_SCALABLE_MODE_DEFAULT_ON by default (commit 77e530c1a864c) + 2. These Intel integrated graphics generations have compatibility issues with DMAR (DMA Remapping) enabled + 3. The interaction between IOMMU scalable mode and the i915 graphics driver causes intermittent display flickering + + This is part of a broader issue affecting multiple Intel integrated + graphics generations (Skylake, KabyLake, CoffeeLake, WhiskeyLake, and + CometLake) as documented in the upstream bug report. Previous patches + have already addressed SKL, KBL, and CML; this patch completes the + series by adding CFL and WHL. + + Affected hardware: Systems with Intel CoffeeLake or WhiskeyLake + integrated graphics (device IDs: 0x3E90-0x3E9C, 0x3EA0-0x3EA9) + + [Fix] + Single UBUNTU SAUCE patch adds CFL and WHL device IDs to the IOMMU quirk list: + + UBUNTU: SAUCE: iommu/intel: disable DMAR for CFL and WHL integrated gfx + - Adds 16 CoffeeLake device IDs (CFL_S, CFL_H, CFL_U variants) + - Adds 5 WhiskeyLake device IDs (WHL_U variants) + - Follows the same pattern as previous SKL/KBL/CML quirk patches + - Device IDs sourced from include/drm/i915_pciids.h for completeness + + This is an Ubuntu-specific SAUCE patch as upstream has not yet provided + a proper fix. The quirk approach is used temporarily until a proper + upstream solution is available. + + Previous related commits in this series: + - fe35c48a46619 "UBUNTU: SAUCE: iommu/intel: disable DMAR for SKL integrated gfx" + - 69a3b8e5f6ebd "UBUNTU: SAUCE: iommu/intel: disable DMAR for KBL and CML integrated gfx" + + [Test Plan] + Test on hardware with CoffeeLake or WhiskeyLake integrated graphics: + + 1. Identify if the system has affected hardware: + ``` + lspci -nn | grep VGA + ``` + Look for Intel graphics with device IDs in the 0x3E90-0x3EA9 range. + + 2. Reproduce the flickering (before the fix): + a. Boot with kernel 6.8.0-x without the patch + b. Move windows around or trigger compositor effects + c. Observe intermittent screen flickering or tearing + + 3. Verify the fix: + a. Boot with kernel containing the patch + b. Check that IOMMU is bypassed for the graphics device: + ``` + sudo dmesg | grep -i "Disabling IOMMU for graphics on this chipset" + ``` + c. Should see: "Disabling IOMMU for graphics on this chipset" + d. Verify no flickering occurs during video playback and window animations + e. Confirm graphics performance remains normal + + [Where problems could occur] + The changes affect the Intel IOMMU driver initialization for CoffeeLake and WhiskeyLake integrated graphics only. + + Potential issues: + + 1. **Security reduction**: Disabling DMAR for integrated graphics + removes IOMMU protection for GPU DMA operations. However, integrated + graphics are generally trusted components, and the security impact is + minimal compared to the usability impact of screen flickering. + + 2. **Hardware-specific behavior**: Some CFL/WHL systems might not + exhibit the flickering issue, and for those systems, this patch + unnecessarily disables IOMMU for graphics. However, the functional + impact is negligible, and disabling DMAR has no negative performance + implications. + + 3. **Interaction with other IOMMU features**: The quirk only affects the + integrated graphics device. Other IOMMU functionality (ATS, interrupt + remapping, etc.) remains unaffected. + + The impact is limited to the IOMMU configuration for CoffeeLake and + WhiskeyLake integrated graphics. All other system components continue to + benefit from IOMMU protection. + + [Other Info] + This is an Ubuntu SAUCE patch (not upstream) that works around the issue until a proper upstream fix is available. + + Upstream tracking bug: + https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/11504 + + The issue was introduced in Ubuntu 6.8 kernel by commit: + 77e530c1a864c "UBUNTU: [Config] enable Intel DMA remapping by default" + + This patch completes a series of quirks for affected Intel graphics generations: + 1. Skylake (SKL) - fe35c48a46619 + 2. KabyLake (KBL) and CometLake (CML) - 69a3b8e5f6ebd + 3. CoffeeLake (CFL) and WhiskeyLake (WHL) - this patch + + All affected device IDs were verified against the upstream i915 driver's + device ID definitions in include/drm/i915_pciids.h. + + ====================================== + Random flickering of the screen when cursor is in the lower part of the screen. The flickering stops when mouse is again moved. - This problem happens on my two laptops (CoffeeLake and WhiskeyLake), details below. Adding + This problem happens on my two laptops (CoffeeLake and WhiskeyLake), details below. Adding intel_iommu=igfx_off to kernel command line solves this problem. Bug https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2062951/+index?comments=all solves the problem for some architectures, but it is now closed. Hence I opened new bug report. Laptop 1: $ lspci -nnk | grep -A3 VGA 00:02.0 VGA compatible controller [0300]: Intel Corporation CoffeeLake-H GT2 [UHD Graphics 630] [8086:3e9b] - DeviceName: Onboard IGD - Subsystem: Hewlett-Packard Company CoffeeLake-H GT2 [UHD Graphics 630] [103c:8427] - Kernel driver in use: i915 + DeviceName: Onboard IGD + Subsystem: Hewlett-Packard Company CoffeeLake-H GT2 [UHD Graphics 630] [103c:8427] + Kernel driver in use: i915 -- 01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GP107GLM [Quadro P1000 Mobile] [10de:1cbb] (rev a1) - Subsystem: Hewlett-Packard Company GP107GLM [Quadro P1000 Mobile] [103c:8427] - Kernel driver in use: nvidia - Kernel modules: nvidiafb, nouveau, nvidia_drm, nvidia + Subsystem: Hewlett-Packard Company GP107GLM [Quadro P1000 Mobile] [103c:8427] + Kernel driver in use: nvidia + Kernel modules: nvidiafb, nouveau, nvidia_drm, nvidia # System Details Report --- ## Report details - **Date generated:** 2025-11-24 21:29:40 ## Hardware Information: - **Hardware Model:** HP HP ZBook Studio G5 - **Memory:** 16.0 GiB - **Processor:** Intel® Core™ i7-8750H × 12 - **Graphics:** Intel® UHD Graphics 630 (CFL GT2) - **Graphics 1:** Quadro P1000 - **Disk Capacity:** 512.1 GB ## Software Information: - **Firmware Version:** Q71 Ver. 01.32.00 - **OS Name:** Ubuntu 24.04.3 LTS - **OS Build:** (null) - **OS Type:** 64-bit - **GNOME Version:** 46 - **Windowing System:** X11 - **Kernel Version:** Linux 6.8.0-88-generic Laptop 2: $ lspci -nnk | grep -A3 VGA 00:02.0 VGA compatible controller [0300]: Intel Corporation WhiskeyLake-U GT2 [UHD Graphics 620] [8086:3ea0] (rev 02) - Subsystem: Lenovo WhiskeyLake-U GT2 [UHD Graphics 620] [17aa:2281] - Kernel driver in use: i915 - Kernel modules: i915 + Subsystem: Lenovo WhiskeyLake-U GT2 [UHD Graphics 620] [17aa:2281] + Kernel driver in use: i915 + Kernel modules: i915 # System Details Report --- ## Report details - **Date generated:** 2025-11-26 14:28:35 ## Hardware Information: - **Hardware Model:** Lenovo ThinkPad P53s - **Memory:** 40.0 GiB - **Processor:** Intel® Core™ i7-8565U × 8 - **Graphics:** Intel® UHD Graphics 620 (WHL GT2) - **Graphics 1:** NV138 - **Disk Capacity:** 1.0 TB ## Software Information: - **Firmware Version:** N2IETA6W (1.84 ) - **OS Name:** Ubuntu 24.04.3 LTS - **OS Build:** (null) - **OS Type:** 64-bit - **GNOME Version:** 46 - **Windowing System:** X11 - **Kernel Version:** Linux 6.8.0-88-generic -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2136958 Title: Random flickering with Intel i915 (CoffeeLake and WhiskeyLake) on Linux 6.8 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2136958/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
