Closes FABRIC-2.md's last open §12 Q5 question. fleet_heartbeat_tick_count
is fed by every live VM's own vm_tick(), not one VM's, so it was reaching
HEARTBEAT_INFERENCE_FREQUENCY (shared/borrowed from the per-VM inference
gate) several times faster than intended with more than one VM live -
backwards from FABRIC.md §22.4's required ~1000:1 separation.
What's actually gated turned out to be low-stakes: vm_physics_tick()
(capsule_vm_physics.c:397) is a passive statistics refit - re-sorts a
window of past heat-transfer samples and recomputes a median rate
estimate. It doesn't move heat or arbitrate capacity. Firing too often
just meant a noisier statistic recomputed more frequently than planned,
not incorrect behavior.
Considered and explicitly rejected: scaling the threshold by live VM
count at the check site. That's the first brick of a scheduler - reading
fleet state to adjust a rate dynamically - which this project has
deliberately avoided building. Implemented instead: STADIUM_CAPACITY_TICK
(existing Kconfig symbol, defined but never read by any code path) now
gates vm_physics_heartbeat_tick()'s call directly, replacing the borrowed
HEARTBEAT_INFERENCE_FREQUENCY. Default bumped 1000 -> 4000, a flat
constant picked once for Tripod's known 4-VM topology, same kind of
placeholder as every other frequency knob in Kconfig.kernel - not
computed from anything at runtime. Renamed fleet_last_inference_tick ->
fleet_last_capacity_tick to match. Still one clock, one counter
(fleet_heartbeat_tick_count) - just a bigger flat divisor on it.
Three-arch QEMU acceptance: all clean to ok>, identical Stadium
conservation invariant on all three (resident_sum=43691 reservoir=21845
sum=65536). logs/20260815-093425/amd64, logs/20260815-093521/aarch64,
logs/20260815-093641/riscv64.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Punch list §25 item 3.8 complete. Added after starting item 4.1
surfaced the need to thread a vm_id into stadium_admit()'s new quota
parameter; Captain Bob ruled UUID/GUID rather than keeping the
narrower uint32_t.
New VMUuid type (vm_uuid.h/vm_uuid.c): two uint64_t halves, RFC-4122-
shaped for logging. Not real randomness -- checked directly against
QEMU 10.2.1's actual CPU feature set: amd64 RDRAND and riscv64 Zkr are
both real, available features here; aarch64 has no RNG property on any
CPU model including "max" (verified exhaustively via QMP
query-cpu-model-expansion). Captain Bob ruled a uniform fallback
across all three ISAs rather than a per-architecture split.
Fallback is a deterministic PRNG (splitmix64) seeded from the Mama
capsule's content hash, pre-filling a 16-entry FIFO pool at boot and
refilling with another batch of the same stream when exhausted --
exactly the shape requested. Same capsule booted twice produces the
same id sequence, preserving the dict_hash reproducibility this
session has relied on throughout.
Hera keeps a fixed, reserved all-zero id, not drawn from the pool --
capsule_birth.c uses vm_id == 0 as a load-bearing sentinel in three
places (KILL protection x2, fleet heat-fanout parent-chain
terminator), found by reading before writing any code.
Two real sentinel-collision bugs caught before shipping, same class as
STADIUM_CONTAINS_NONE: vm_uuid_none() (all-ones, not all-zero) for
"not yet assigned"/"no VM" placeholders; confirmed item 3.7's quota
table already used an in_use boolean rather than a vm_id sentinel, so
no second collision was actually possible there -- the dead,
never-referenced STADIUM_QUOTA_SLOT_EMPTY macro was removed.
Blast radius larger than first scoped, flagged mid-work rather than
silently absorbed: capsule_vm_physics.c/.h (the fleet heat-transfer
layer item 2.1 modified earlier this session) has its own vm_id-keyed
node table and walks parent_vm_id chains through the same identity
space, so it needed the same change, plus its callers in
mama_forth_words.c and sk_vm_bootstrap.c.
One live FORTH word contract changed, by explicit ruling: CAPSULE-BIRTH
was ( capsule-id -- vm-id ), a single cell -- can't hold 128 bits.
Captain Bob picked pushing two cells ("there is doubles support in the
FORTH std word set anyway"): ( capsule-id -- vm-id-hi vm-id-lo ).
MAMA-VM-ID changed the same way: ( -- 0 0 ).
Verified: full (not standalone-file) kernel rebuild to catch cross-file
breakage given the size of this change -- it surfaced the
capsule_vm_physics.c blast radius a narrower check would have missed.
Three-architecture boot (amd64, aarch64, riscv64), all reaching ok>
with identical dict_hash=0x3d4e1daf289da94f matching the item-3.7
baseline.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Punch list §25 item 2.1 complete.
vm_physics_touch() no longer takes a wall-clock timestamp -- it reads
fleet_heartbeat_tick_count internally, which is execution-paced
(vm_runtime.c:143), not wall-clock. VMPhysics.last_active_ns ->
last_active_tick, VMFleetTouchSample.elapsed_us -> elapsed_ticks, and a
new explicit `touched` flag replaces the old `> 0` sentinel (tick 0 is
a legitimate value a first touch can land on, unlike wall-clock ns).
Verified: three-architecture boot (amd64 x2, aarch64, riscv64), all
reaching ok> with identical dict_hash=0x3d4e1daf289da94f matching the
item-0.10 baseline. No new compiler warnings in the touched files.
Honestly flagged, not fixed: with Tripod pruned to Hera alone (item
0.1), vm_physics_touch()'s fan-out has no other live VM to pull heat
from, so the fleet-heat-sum acceptance criterion is trivially satisfied
rather than genuinely stress-tested -- a real check needs Phase 4's
multi-VM fleet. fleet_transfer_slope_q48's seed (65536/3) was
calibrated for elapsed microseconds and has not been re-fit for elapsed
ticks; left as-is rather than guessed, deferred to item 5.1's DoE work.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
