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charset=\"utf-8\"", "Content-Transfer-Encoding": "base64", "Errors-To": "kernel-team-bounces@lists.ubuntu.com", "Sender": "\"kernel-team\" <kernel-team-bounces@lists.ubuntu.com>" }, "content": "BugLink: https://bugs.launchpad.net/bugs/2148627\n\n[Impact]\n\nGoogle reported to us that some of their hardware fails to finish booting due to\na kernel hang on 22.04 linux-gcp-6.8. This issue was traced to IOMMU passthrough\nbeing enabled by default, which was to originally resolve LP: #2085904. The\nroot cause of that issue was fixed via a firmware update, so IOMMU passthrough\nno longer needs to be enabled by default, and this config change can now be\nreverted. On a test kernel with the change reverted, the new issue reported by\nGoogle is no longer reproducible.\n\n[Fix]\n\nRemove the config annotations that enable IOMMU passthrough by default.\n\n[Test Plan]\n\nTo confirm that the C3-metal issue is resolved, repeat the test plan for LP:\n#2085904. Any failures indicate that IOMMU passthrough needs to remain enabled\nby default.\n\nTo confirm that the new issue is resolved, verify that the specified hardware\nis able to now boot after the change is applied, without hanging during IOMMU\ninitialization.\n\n[Regression potential]\n\nRegression potential is low because the annotation change is provably effective\nat changing the config, and we can confirm both of the affected instance types\nhave their original problems resolved by the change.\n\nIan Whitfield (1):\n UBUNTU: [Config] gcp-6.8: Disable IOMMU passthrough by default\n\n debian.gcp-6.8/config/annotations | 9 ---------\n 1 file changed, 9 deletions(-)" }