[auser]

Summary

Add a resident, kernel-only publication/claim substrate for canonical signed Linux kernels. This does not enable a warm claim, change an admitted launch, hand a descriptor to a VMM, or establish a full boot closure.

What changed

• Require an explicit byte/owner-FD budget before reserving an ID or staging a kernel. Authenticate the canonical owner and selected bytes, copy to a Linux memfd, seal it before validating the final digest, and issue a nonserializable owner-epoch/generation handle.
• On claim, recheck canonical identity, current revocation/publisher selection and memfd seals without rehashing the payload. Expose bounded reads, not a duplicable descriptor. Removal blocks new claims and retains an active publication until its in-process readers release it.
• Add refusal and race regressions, a signed-kernel test requiring the pinned public kernel, and update ADR-059's preview status. Keep the merged main branch's existing footprint ceilings; this change fits beneath them.

Validation

• Prior to rebasing on current main: cargo check --workspace, cargo clippy --locked -p mvm-runtime --lib --tests -- -D warnings, Linux-target cargo-zigbuild check -p mvm-runtime --tests, cargo fmt --all -- --check, two boot-input budget tests and ten existing snapshot-service tests passed. The footprint, file-size, claim-catalog and declared-backing gates passed.
• Same-head CI is pending. Linux syscall tests and the ignored signed-kernel fixture test were not run locally. cargo test --workspace was started but stopped during compilation; Linux-target Clippy could not build ring with the installed cross-C toolchain.

Review focus

This service keeps the file and reservation in one process. No raw descriptor escapes and a dropped read lease does not purport to prove a detached VMM's exit. The eventual VMM handoff needs a separately reviewed last-child/process-lifetime budget owner and live scoped Firecracker witnesses before warm claims can be considered. No PR-only fixture becomes a publisher or release identity.

Linked

• Follows merged fix(runtime): guard trusted snapshot publication lifecycle #5407. Draft feat(pack): stage portable composition from current main #5326 remains separate and is not release evidence.

[auser]

Validation on 889008f: CI 43389807351 passed, including Linux workspace tests, invariant gates, feature-combination Clippy, formatting and core Clippy. Local cargo clippy --workspace -- -D warnings and cargo fmt --all -- --check passed; focused snapshot-service tests passed (12/12). The first local cargo test --workspace run hit seven unrelated Unix-socket SUN_LEN failures under Delta’s long TMPDIR; TMPDIR=/tmp cargo test --locked -p mvm-backends --lib passed (435/435), and the full short-TMPDIR workspace rerun is in progress. The ignored signed-kernel fixture test requiring MVM_TEST_CANONICAL_KERNEL was not run. No VMM descriptor handoff or warm-boot evidence is claimed.

[auser]

Final local validation: TMPDIR=/tmp cargo test --workspace passed, including doc tests. The short TMPDIR avoids the macOS Unix-socket path-length failures observed with Delta’s default temporary path. cargo clippy --workspace -- -D warnings passed. PR CI 43389807351 passed; the merge queue is validating the merge-group commit. The signed-kernel fixture test remains ignored without MVM_TEST_CANONICAL_KERNEL, and no VMM/warm claim is implied.