starkernel: item 3.5 -- admission and eviction
Punch list §25 item 3.5 complete. stadium_admit(candidate) places into an unused cell if one exists (no comparison needed), otherwise finds the least-dense resident -- skipping pinned and contains-gated patrons, which are never eviction candidates -- and evicts it only if the candidate is strictly denser, per §19.3. stadium_evict(cell_index) dispatches the departing patron's behaviour before clearing its slot, per §17.2. Caught a real bug before it ran: the first draft used contains == 0 to mean "holds nothing," but cell index 0 is a valid index (Hera, item 3.6). Fixed with a proper sentinel, STADIUM_CONTAINS_NONE (UINT32_MAX). A second-pass review found mass was not accounted for: both functions handled exactly one cell regardless of the candidate's stated mass, which leaks cells on eviction of any mass > 1 patron and breaks capacity conservation. Fixed by refusing any candidate with mass != 1 -- multi-cell patrons need the per-VM free lists item 3.2 already deferred (§22.3), not built here. Documented, not fixed: the discriminator bitmap can't distinguish free from continuation cells, so the free-cell scan reads continuation-cell payload bytes under the header layout -- latent since nothing creates continuation cells yet, and the mass != 1 refusal keeps it provably latent. Superseded by the free list when it exists. Unexercised at runtime: nothing calls either function yet (no real patron kind is wired to the Stadium). No self-test added -- filling ~74,000+ cells to reach the eviction-on-full branch was judged impractical, following item 2.2's own precedent for its unexercised fleet-full path. Verified: three-architecture boot (amd64, aarch64, riscv64), all reaching ok> with identical dict_hash=0x3d4e1daf289da94f matching the item-3.4 baseline. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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Robert Allan James
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Claude Sonnet 5
Claude Sonnet 5
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