starkernel: item 3.8 -- VM identifiers as UUID/GUID
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>
This commit is contained in:
Robert Allan James
co-authored by
Claude Sonnet 5
Claude Sonnet 5
parent
ec2c97ef70
commit
9b305a5be7
@@ -0,0 +1,101 @@
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/*
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StarForth — Steady-State Virtual Machine Runtime
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Copyright (c) 2023–2025 Robert A. James
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All rights reserved.
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This file is part of the StarForth project.
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Licensed under the StarForth License, Version 1.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at:
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https://github.com/star.4th@proton.me/StarForth/LICENSE.txt
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This software is provided "AS IS", WITHOUT WARRANTY OF ANY KIND,
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express or implied, including but not limited to the warranties of
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merchantability, fitness for a particular purpose, and noninfringement.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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/**
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* vm_uuid.h - 128-bit VM identifiers (FABRIC.md punch list item 3.8)
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*
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* Replaces capsule_birth.c's monotonic uint32_t vm_id with a wider,
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* RFC-4122-shaped identifier. NOT real randomness: this kernel has no RNG
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* source at all (checked directly against QEMU 10.2.1's actual CPU feature
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* set -- amd64 RDRAND and riscv64 Zkr are both available, aarch64 has
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* neither RNDR nor any RNG property on any CPU model including "max"), and
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* Captain Bob ruled a uniform fallback across all three ISAs rather than a
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* per-architecture split. Values are generated by a deterministic PRNG
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* (splitmix64) seeded from the Mama capsule's content hash -- the same
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* capsule booted twice produces the same ID sequence, preserving the
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* run-to-run reproducibility this project has relied on everywhere else
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* (the dict_hash regression check after every prior item this session).
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*/
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#ifndef STARKERNEL_VM_UUID_H
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#define STARKERNEL_VM_UUID_H
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#ifdef __STARKERNEL__
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#include <stdint.h>
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typedef struct {
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uint64_t hi;
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uint64_t lo;
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} VMUuid;
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/*
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* vm_uuid_hera - The fixed, reserved identifier for Hera (patron zero,
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* item 3.6; VM 0 in the pre-item-3.8 scheme). Not drawn from the pool --
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* capsule_birth.c's KILL logic ("Hera cannot be killed") and the fleet
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* heat-fanout parent-chain sentinel (capsule_run.h's `parent_vm_id`
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* comment: "self-referential, parent_vm_id == vm_id == 0") both depend on
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* Hera's id being a fixed, cheaply-comparable value, exactly as 0 was
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* before this item. All-zero.
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*/
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VMUuid vm_uuid_hera(void);
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int vm_uuid_is_hera(VMUuid id);
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/*
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* vm_uuid_none - Sentinel meaning "no id" / "slot not in use." All-ones --
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* NOT all-zero, because all-zero is Hera's reserved value (item 3.8 caught
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* this collision before writing any code that could have repeated the
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* STADIUM_CONTAINS_NONE mistake at a new site).
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*/
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VMUuid vm_uuid_none(void);
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int vm_uuid_is_none(VMUuid id);
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int vm_uuid_equal(VMUuid a, VMUuid b);
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/*
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* vm_uuid_pool_init - Seed the generator. Call once, after the Mama
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* capsule's content hash is known (right after capsule_birth_mama()
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* succeeds) and before the first non-Hera VM birth. Idempotent to call
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* again (re-seeds and refills), though nothing does today.
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*/
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void vm_uuid_pool_init(uint64_t seed);
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/*
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* vm_uuid_next - Pop the next id from the pre-filled FIFO pool, refilling
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* with a fresh batch (continuing the same deterministic splitmix64 stream)
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* when empty. If called before vm_uuid_pool_init() (not the intended path),
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* self-seeds from a fixed default rather than returning garbage -- flagged
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* as a safety net, not normal use.
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*/
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VMUuid vm_uuid_next(void);
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/*
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* vm_uuid_format - Writes the RFC-4122-shaped string
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* "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" (36 chars + NUL) into buf.
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* @param buf Caller-provided buffer, at least 37 bytes.
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*/
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void vm_uuid_format(VMUuid id, char *buf);
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#endif /* __STARKERNEL__ */
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#endif /* STARKERNEL_VM_UUID_H */
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