[SRU][J:linux-gcp-6.8][PATCH 0/1] Disable IOMMU Passthrough by default

[Ian Whitfield]

BugLink: https://bugs.launchpad.net/bugs/2148627

[Impact]

Google reported to us that some of their hardware fails to finish booting due to
a kernel hang on 22.04 linux-gcp-6.8. This issue was traced to IOMMU passthrough
being enabled by default, which was to originally resolve LP: #2085904. The
root cause of that issue was fixed via a firmware update, so IOMMU passthrough
no longer needs to be enabled by default, and this config change can now be
reverted. On a test kernel with the change reverted, the new issue reported by
Google is no longer reproducible.

[Fix]

Remove the config annotations that enable IOMMU passthrough by default.

[Test Plan]

To confirm that the C3-metal issue is resolved, repeat the test plan for LP:
#2085904. Any failures indicate that IOMMU passthrough needs to remain enabled
by default.

To confirm that the new issue is resolved, verify that the specified hardware
is able to now boot after the change is applied, without hanging during IOMMU
initialization.

[Regression potential]

Regression potential is low because the annotation change is provably effective
at changing the config, and we can confirm both of the affected instance types
have their original problems resolved by the change.

Ian Whitfield (1):
  UBUNTU: [Config] gcp-6.8: Disable IOMMU passthrough by default

 debian.gcp-6.8/config/annotations | 9 ---------
 1 file changed, 9 deletions(-)

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2.43.0