Files
LithosAnanake/src/starkernel/vm
Robert Allan JamesandClaude Sonnet 5 cc6c8c43f3 Fix ABORT to actually unwind to QUIT instead of one level
ABORT is documented and tested in this codebase as standard FORTH-79
behavior -- system_words_test.c:63: "Should clear stacks and return to
QUIT" -- meaning it should unwind all the way back to the outermost
interpreter loop, abandoning whatever's left of the current line/block.
The implementation only unwound one level: every place that checked
vm->abort_requested cleared it the instant it saw it, so it never
survived to propagate past the first nested frame.

This surfaced via Artemis's ART-HALT-UNRECOG (capsules/artemis/init.4th):
on an unrecognized disk it correctly printed "ARTEMIS HALT: unrecognized
disk content" and called ABORT, but WELCOME (the next line in the same
block) ran anyway, and Artemis announced ready to Hermes and joined the
fleet normally -- contradicting .claude/ARTEMIS.md's "Refuse to mount...
do not overwrite it" requirement. Root cause is general, not
Artemis-specific, and present identically in both the hosted and kernel
VM cores.

Fixed at every level execution can nest through, verified by exhaustively
grepping every !vm->error-gated continuation loop and adding the parallel
!vm->abort_requested check:

- execute_colon_word (src/vm.c, src/starkernel/vm/vm_core.c): stop
  clearing the flag on return -- every colon-word call is a recursive
  call to this same function, so leaving it set lets every enclosing
  frame's own check also unwind.
- vm_interpret (src/vm.c, src/starkernel/vm/vm_core.c): stop parsing
  further words in the current input string once the flag is set.
- exec_block_with_retry (src/starkernel/capsule/capsule_loader.c):
  capsule birth's line-by-line block executor -- stop processing further
  lines in the current block, but return 0 (not -1), so
  capsule_exec_payload still loads later blocks in the same capsule
  payload. Returning -1 here would have silently broken word definitions
  in blocks that come after the aborting one for reasons unrelated to
  why it aborted (concretely, Artemis's ART-PING/LOAD-DOE in blocks
  4851/4852, which follow the entry block 4133).
- THRU and --> (src/word_source/block_words.c): stop processing further
  blocks/lines in their own loops.
- DODOES (src/word_source/defining_words.c): the CREATE...DOES> runtime
  has its own hand-rolled execution loop, separate from
  execute_colon_word -- same bug class, same fix. Also guarded the
  post-loop "if (vm->rsp < base_rsp) vm->rsp = base_rsp" clamp so it
  doesn't fire on an abort exit -- ABORT's own reset_vm_state() already
  set rsp; restoring it to base_rsp would have partially undone that.
- Both REPL loops (src/repl.c, src/starkernel/repl.c x2 call sites):
  clear the flag after each line, mirroring the existing vm->error
  pattern, so a mid-line abort doesn't silently freeze subsequent
  interactive input.

Verified directly: ": AB-TEST 1 2 3 ABORT 999 . ;  AB-TEST 42 . CR
777 . CR" -- 999 never prints (stops mid-colon-word), 42 never prints
(stops the rest of the same line), 777 prints fine (next line
unaffected). Artemis: WELCOME/"Artemis ready" no longer fires after the
halt message. No regression: all three architectures still show PASS:
persist-read, PASS: E2E msg flow, and matching dict_hash on the normal
(non-aborted) boot path; hosted test suite 965 passed / 0 failed.

Known follow-up, not fixed here (see memory for details): Artemis still
announces ready to Hermes via a separate call path (CD-INIT, block 4141)
that never went through capsule_exec_payload's block chain in the first
place, and the disk file still picks up incidental writes even on a
correctly-halted boot -- likely generic block-subsystem housekeeping,
not traced yet.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
2026-08-02 10:07:18 -04:00
..
2026-08-01 07:49:56 -04:00

src/starkernel/vm/

Kernel-side StarForth VM subsystem.

  • vm_core.c — kernel port of the core interpreter loop.
  • vm_runtime.c — kernel VM runtime support.
  • vm_bootstrap.c — kernel VM bootstrap (distinct from bootstrap/sk_vm_bootstrap.c, which owns the higher-level subsystem wiring called from kernel_main.c).
  • arena.c — capsule arena allocator (fixed-region allocation for capsule payload data).
  • parity.c — birth/execution parity logging (VM ID + capsule hash + dictionary hash), enabling offline determinism verification.
  • alloc_kernel.c — the kernel-side implementation of the VM's allocator interface actually referenced by Makefile.starkernel's build (see src/platform/README.md for a note on a second, unwired copy).
  • q48_stubs.c — deliberate no-op stubs for q48_from_double()/ q48_to_double() in the freestanding kernel build, where floating point is unavailable; always returns zero, safe because shared VM code only uses these results for logging/diagnostic paths that are inactive in the kernel build.
  • vm_internal.h — internal-only declarations shared across this directory's files.

Subdirectories:

  • bootstrap/sk_vm_bootstrap.c — owns VM init + capsule loading wiring, called from kernel_main.c; kernel_main.c itself only owns hardware milestones.
  • host/shim.c — host-service shim bridging the kernel VM to src/starkernel/hal/host_services.c.