[Alex Cortelyou (acortelyou)]

Merge Checklist

All boxes should be checked before merging the PR (just tick any boxes which don't apply to this PR)

• The toolchain has been rebuilt successfully (or no changes were made to it)
• The toolchain/worker package manifests are up-to-date
• Any updated packages successfully build (or no packages were changed)
• Packages depending on static components modified in this PR (Golang, *-static subpackages, etc.) have had their Release tag incremented.
• Package tests (%check section) have been verified with RUN_CHECK=y for existing SPEC files, or added to new SPEC files
• All package sources are available
• cgmanifest files are up-to-date and sorted (./cgmanifest.json, ./toolkit/scripts/toolchain/cgmanifest.json, .github/workflows/cgmanifest.json)
• LICENSE-MAP files are up-to-date (./LICENSES-AND-NOTICES/SPECS/data/licenses.json, ./LICENSES-AND-NOTICES/SPECS/LICENSES-MAP.md, ./LICENSES-AND-NOTICES/SPECS/LICENSE-EXCEPTIONS.PHOTON)
• All source files have up-to-date hashes in the *.signatures.json files
• sudo make go-tidy-all and sudo make go-test-coverage pass
• Documentation has been updated to match any changes to the build system
• Ready to merge

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Summary

During Hyper-V live migration, VF teardown can contend with route programming for RTNL, delaying netlink operations beyond networkd's default 25-second timeout. A route timeout can leave the interface failed and stop Router Advertisement processing, eventually allowing the IPv6 default route to expire.

Observed successful VF teardown durations approach 60 seconds, suggesting--but not confirming--a VF-operation timeout around that threshold.

Increasing the timeout to 100 seconds provides margin above the observed threshold while retaining a finite timeout. This complements the failure-recovery patchset by reducing avoidable transitions into the failed state.

Change Log

• Package a systemd-networkd service drop-in setting SYSTEMD_NETLINK_DEFAULT_TIMEOUT=100s.
• Increment systemd and its signed boot package to release 255-37, and register the new source and SHA256 hash.
• Normal successful operations are unchanged. Genuinely unanswered requests can remain pending 75 seconds longer before timeout-based failure handling. The setting affects networkd's default-timeout netlink requests generally, not only IPv6 routes.

Does this affect the toolchain?

NO. This changes systemd-networkd's runtime configuration, not the toolchain.

Associated issues

• systemd issue 25441 documents the route-timeout failure behavior.

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