Third stage of the preemptive context-switching plan. The real save/restore switch mechanism now exists -- the first time anything has ever executed on a VM's own native stack (Stage 1 allocated them, unused). New sk_vm_switch_to() (switch.S, one per arch) is an ordinary function call, not an interrupt -- so unlike Stage 0's trap frame, the ABI already covers every caller-saved register; only the callee-saved set needs explicit save/restore (amd64: rbx/rbp/r12-r15, no FP at all since SysV has no callee-saved XMM; aarch64: x19-x28/x29/x30 + d8-d15; riscv64: s0-s11/ra + fs0-fs11, FS-gated like Stage 0 but read once and reused for both halves within one call, since FS is genuine global CPU state, not part of what's switched). A sibling sk_vm_switch_prime() in the same file builds the synthetic first-entry frame, kept in assembly so the layout can never drift out of sync with sk_vm_switch_to() itself. New switch.c/switch.h: sk_vm_context_switch(from, to) handles first-entry priming vs. resuming a parked context, and updates registry state (new VM_STATE_SWITCHED_OUT, distinct from VM_STATE_STOPPED -- STOPPED means no live frame, this means the opposite). sk_vm_switch_entry() is the minimal permanent trampoline every freshly-entered VM lands in: no production behavior defined yet, so it just yields straight back to whoever switched to it, forever. Closes the confirmed unguarded-KILL UAF found during planning: capsule_vm_kill(), mama_word_kill(), and capsule_vm_kill_all_nonmama() all now refuse (or silently leak rather than free, on the cold-restart path where arch_cold_reset() wipes everything immediately after anyway) tearing down a switched-out VM. Side effect found, not built on purpose: the existing MSG-TICK idle-pump already filters on VM_STATE_LIVE, so it automatically stopped dispatching into a switched-out VM with zero changes needed there. Verified via a temporary SWITCH-TEST probe (boot-triggered, since nothing can type interactively into a foreground-only QEMU session) that round-tripped a sentinel through 5 real Hera<->Hermes switches on all 3 architectures: 5/5 rounds, 0 failures, clean continuation to ok>. Probe fully reverted after capture; kernel_main.c shows zero diff. Also: Makefile.starkernel's LOADER_EXTRA_SRCS/LOADER_ASM needed the new files added explicitly (this project's "loader" PE binary is the full running kernel, not a thin bootstrap stage), and aarch64's switch.S needed the same #ifndef _WIN32 guard around .hidden that isr.S already carries (aarch64's loader assembles via clang targeting a PE/COFF target with no .hidden equivalent) -- caught by a build failure, fixed. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_016UNhH1mhi52i6Qihh7ZV5S
Bare-Metal DoE Experiment
This directory holds data and analysis from the LithosAnanke kernel's Design of Experiments (DoE) runs — blind full-factorial 2⁴ experiments that measure the L8 Jacquard mode selector's effect on the Steady-State Machine across all three supported architectures (amd64, aarch64, riscv64).
Directory Layout
experiments/bare_metal/
├── runs/ ← timestamped canonical CSVs from every acceptance run
├── latest/ ← arch-named copies of the most recent run (human-readable)
│ ├── amd64.csv
│ ├── aarch64.csv
│ └── riscv64.csv
└── analysis/
├── charts/ ← generated SVG/PNG charts
├── report/ ← timestamped LaTeX / Markdown reports
└── tables/ ← generated summary tables
runs/ is the canonical archive. latest/ is the eyeball-friendly shortcut
— always the most recent run per architecture, overwritten on each new run.
Running the DoE
The DoE runs automatically when the kernel boots because init.4th calls it.
The standard acceptance command runs all three architectures sequentially:
make -f Makefile.starkernel ARCH=amd64 clean qemu
make -f Makefile.starkernel ARCH=aarch64 clean qemu
make -f Makefile.starkernel ARCH=riscv64 clean qemu
Each run executes 48 trials (16 L8 configs × 3 reps, Fisher-Yates shuffled), captures ~1.27 million heartbeat rows per architecture, and writes two files:
| File | Path |
|---|---|
| Timestamped canonical CSV | experiments/bare_metal/runs/doe-<arch>-<YYYYMMDD-HHMMSS>.csv |
| Latest convenience copy | experiments/bare_metal/latest/<arch>.csv |
Run architectures sequentially, never in parallel. All three QEMU
instances use accel=tcg (software emulation). Concurrent runs compete for
host CPU and corrupt the timing signal that the DoE is measuring.
Disabling the DoE
To boot into the REPL without running the experiment, comment out the last
two lines of capsules/init.4th:
Block 2049
( first init.4th )
: STAR 42 EMIT ;
: STARS 0 DO STAR LOOP ;
: MARGIN 30 SPACES ;
: BAR MARGIN 5 STARS CR ;
: BLIP MARGIN STAR CR ;
: F CR BAR BLIP BAR BLIP BLIP CR ;
( S" Hermes" BIRTH )
( S" Artemis" BIRTH )
( S" doe.4th" EXEC ) ← comment this out
( 123456 3 L8-DOE ) ← comment this out
The kernel will boot to the ok> REPL with no experiment running.
Commenting both lines leaves doe.4th unloaded so none of its words
(L8-DOE, WL-NAME, etc.) are defined, which is the cleanest state for
interactive sessions.
Changing the Seed and Rep Count
The DoE entry point is L8-DOE ( seed reps -- ).
The call in init.4th is:
123456 3 L8-DOE
-
Seed — any non-zero integer. The same seed always produces the same shuffled run order, so results are reproducible. Change the seed to explore a different permutation; different seeds are statistically equivalent but verify shuffle-independence.
-
Reps — trials per L8 configuration (1–200). 3 reps × 16 configs = 48 runs, which takes roughly 25–30 minutes per architecture under TCG. Increase for higher statistical power; decrease for quick smoke checks.
( quick smoke check — 1 rep, 16 runs total )
42 1 L8-DOE
( full study — 10 reps, 160 runs )
987654 10 L8-DOE
What Are Capsules?
A capsule is a named blob of FORTH-79 source text stored in capsules/.
The kernel's EXEC word loads a capsule by filename and interprets it as
FORTH source. BIRTH (commented out in init.4th) would instead spawn an
isolated child VM whose sole personality is that capsule's code.
There are two roles:
| Role | Who uses it | What it does |
|---|---|---|
| Init capsule | Mama VM at boot | Defines the VM's vocabulary and behavior |
| Workload capsule | DoE machinery | Provides a computational task to time |
init.4th is the Mama VM's init capsule — executed exactly once at kernel
boot, and the only file mkcapsule special-cases by exact filename as the
active MAMA_INIT capsule. The numbered files (workload-0.4th …
workload-9.4th) and the L8 variant files (init-l8-*.4th) are alternate
personality capsules, not a workload dispatched by doe.4th's own DoE —
doe.4th generates its own synthetic arithmetic workload internally
(DOE-WORK) and has no pluggable per-workload dispatch table today. To
exercise one of the numbered capsules' own workload, substitute it in as
the boot's init.4th (e.g. cp capsules/workload-3.4th capsules/init.4th
before building) rather than wiring it into doe.4th.
.4th File Structure
Every .4th file must follow StarForth's block format. The block system
maps source text to 1024-byte logical blocks; the Block NNNN header tells
the loader which block slot to fill.
Mandatory rules:
- The first line of each logical block must be
Block NNNN(capital B, single space, decimal integer). - Block numbers must be unique within a single capsule file.
- Blocks are loaded in file order and executed top-to-bottom.
- Each block can hold up to 1024 bytes of source text.
- Comments use
( ... )— parentheses with spaces inside. - Word definitions use
: NAME ... ;— standard FORTH-79.
Minimal capsule skeleton:
Block 3100
( My capsule description )
: MY-WORD ( -- )
42 . CR ;
MY-WORD
Multi-block capsule:
Block 3100
( Block 1: helpers )
: HELPER ( n -- n*2 ) 2 * ;
Block 3101
( Block 2: main logic )
: MAIN ( -- )
10 0 DO I HELPER . CR LOOP ;
MAIN
The block number namespace is shared across all loaded capsules. Convention used in this repository:
| Range | Contents |
|---|---|
| 2048–2099 | init.4th (Mama VM boot sequence) |
| 2100–2199 | doe.4th (DoE machinery) |
| 3000–3999 | Reserved for user-defined workload capsules (see below) |
| 4000+ | User-defined capsules |
Adding a Custom Workload Capsule
Step 1 — Create the file.
Add capsules/my-workload.4th using block numbers in the 4000+ range:
Block 4000
( my-workload.4th - description of what this measures )
: MY-COMPUTE ( n -- )
0 SWAP 0 DO I 3 * + LOOP DROP ;
Block 4001
( main entry point )
: RUN-MY-WORKLOAD ( -- )
500 0 DO I MY-COMPUTE LOOP ;
RUN-MY-WORKLOAD
The last line should execute the workload so EXEC runs it immediately when
the capsule is loaded.
Step 2 — Run it.
doe.4th has no pluggable workload dispatch table today — its own
factorial (entropy/CV/temporal-decay/stability × reps) drives a single
self-contained synthetic workload (DOE-WORK, Block 2103), not a file
picked from a list. To measure your own workload's physics behavior
instead, run it standalone as the boot's own capsule rather than trying
to wire it into doe.4th's factorial:
cp capsules/my-workload.4th capsules/init.4th # substitutes it in
make -f Makefile.starkernel ARCH=amd64 clean qemu
(mkcapsule special-cases the exact filename init.4th as the one
capsule flagged MAMA_INIT and loaded at boot — this is genuinely a
substitution, not a selection from a list, so restore the real init.4th
afterward, e.g. git checkout capsules/init.4th.)
Your workload's heartbeat rows will appear in the CSV the same way any
boot's do — match by the DOE-RUN marker lines described below, once your
capsule's own trial-loop word emits one the same way doe.4th's does.
CSV Format
Each row emitted by the [HADES][DOE ] serial tag is one heartbeat tick
during a workload execution. Extract with:
grep -aP '\[HADES\]\[DOE \]' logs2/qemu-amd64-<timestamp>.log \
| sed 's/.*\[DOE \] //' > my.csv
Columns (15 total):
| # | Name | Type | Description |
|---|---|---|---|
| 1 | tick_number |
uint32 | Monotonic heartbeat counter |
| 2 | elapsed_ns |
uint64 | Nanoseconds since run start |
| 3 | tick_interval_ns |
uint64 | Interval from prior tick |
| 4 | cache_hits_delta |
uint32 | Hot-words cache hits this tick |
| 5 | bucket_hits_delta |
uint32 | Bucket hits this tick |
| 6 | word_executions_delta |
uint32 | Words executed this tick |
| 7 | hot_word_count |
uint64 | Words with heat ≥ threshold |
| 8 | avg_word_heat_q48 |
uint64 | Mean heat (raw Q48.16 integer) |
| 9 | window_width |
uint32 | L8's target rolling window size |
| 10 | actual_window_size |
uint32 | True analysis width: min(total_executions, window_width) |
| 11 | predicted_label_hits |
uint32 | ANOVA early-exit confirmations (L8 validation signal) |
| 12 | jitter_bits |
uint64 | Estimated jitter (IEEE 754 bit pattern) |
| 13 | apic_ticks |
uint64 | APIC timer monotonic count |
| 14 | time_trust_q48 |
uint64 | Time-trust score (Q48.16) |
| 15 | variance_q48 |
uint64 | Timing variance (Q48.16) |
avg_word_heat_q48 is a raw fixed-point integer. To convert to a human-readable
heat value: avg_word_heat = avg_word_heat_q48 / 65536.0.
jitter_bits is the IEEE 754 double-precision bit pattern of the jitter in
nanoseconds. In R: readBin(as.raw(…), "double"). In Python:
struct.unpack('d', struct.pack('Q', n))[0].
Interpreting predicted_label_hits
This column is the feedback-loop closure signal.
Each non-zero value means the inference engine ran ANOVA on the current execution window and confirmed the L8 selector's config choice correlated with the subsequent execution pattern — an "early exit" because the statistical test converged without needing all data.
- High rate → L8 chose well; the system settled quickly into a stable regime.
- Low rate → L8 is still searching; the workload is novel or transient.
- Zero throughout → The workload ended before the inference engine had enough data, or the window is too small to trigger ANOVA.
This is the metric that closes the loop between "L8 made a choice" and "that choice was actually validated by what the VM did next."