This bug is awaiting verification that the linux-
gcp-6.11/6.11.0-1011.11~24.04.1 kernel in -proposed solves the problem.
Please test the kernel and update this bug with the results. If the
problem is solved, change the tag 'verification-needed-noble-linux-
gcp-6.11' to 'verification-done-noble-linux-gcp-6.11'. If the problem
still exists, change the tag 'verification-needed-noble-linux-gcp-6.11'
to 'verification-failed-noble-linux-gcp-6.11'.


If verification is not done by 5 working days from today, this fix will
be dropped from the source code, and this bug will be closed.


See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how
to enable and use -proposed. Thank you!


** Tags added: kernel-spammed-noble-linux-gcp-6.11-v2 
verification-needed-noble-linux-gcp-6.11

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https://bugs.launchpad.net/bugs/2086587

Title:
  Random flickering with Intel i915 (Comet Lake and Kaby Lake) on Linux
  6.8+

Status in linux package in Ubuntu:
  Fix Released
Status in linux source package in Jammy:
  Invalid
Status in linux source package in Noble:
  Fix Released
Status in linux source package in Oracular:
  Fix Released
Status in linux source package in Plucky:
  Fix Released

Bug description:
  [Impact]
  The flickering predominantly occurs when the mouse cursor is in the bottom 
quarter of the screen and stops when the cursor leaves this area.
  Extensive testing across various kernel versions revealed that the issue 
became apparent from kernel version 6.8.0 onward, correlating with the 
mentioned configuration changes, CONFIG_INTEL_IOMMU_DEFAULT_ON and 
CONFIG_INTEL_IOMMU_SCALABLE_MODE_DEFAULT_ON.
  The problem persists in the latest drm tip.

  [Fix]
  As an immediate workaround, adding 'intel_iommu=igfx_off' to the kernel 
command line has been found to effectively eliminate the flickering issue.
  This patch proposes the same behavior as 'intel_iommu=igfx_off' and apply the 
rule to all Intel KBL and CML GPU IDs.

  [Test]
  1. Boot up to desktop with ubuntu kernels(6.8+)
  2. Moving cursor around the desktop
  3. There should be no flicker while cursor is moving

  [Where problems could occur]
  For virtualized environments using hardware-assisted virtualization for 
graphics (such as VFIO or mediated pass-through), disabling IOMMU for graphics 
could either disable these features or reduce their security and efficiency.
  Usually, users pass the 'intel_iommu=on' by themselves when they are using 
related features. So, the impact of this change is minimal.

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