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

[Kevin Becker]

On Thu, Apr 16, 2026 at 8:23 PM Ian Whitfield <ian.whitfield at canonical.com>
wrote:

> 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(-)
>
> --
> 2.43.0


 Acked-by: Kevin Becker <kevin.becker at canonical.com>
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