Robert Allan JamesandClaude Sonnet 5
66beae7fd4
Implements the message-arrival eligibility signal FABRIC-3.md §XXVIII.1 left open (has_work per-slot flag, set via new SWITCH-MARK-WORK primitive from MSG-SEND) so an idle VM never becomes a switch target purely by waiting out the readiness threshold. Also root-causes and fixes a second, independent switch-storm: the tick's "who is current" check used vm_log_attributed_vm(), which can't see a VM parked in switch.c's own raw trampoline. Replaced with a dedicated g_switch_current_vm tracked by the switch mechanism itself, and moved target-slot eligibility reset to the switch decision point instead of relying on ISR polling to observe a window that can be only a few instructions wide. Verified live on all 3 architectures: clean boot to zuse@Hera] ok>, live cross-VM message dispatch, and (since a quiet log looks identical to a livelocked storm once the DoE probe is gone) confirmed genuine REPL liveness via QMP send-key + screendump on aarch64/riscv64, not log inspection alone. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01BWpNjdwPtFLuVLaAq44L9K
61 lines
2.2 KiB
C
61 lines
2.2 KiB
C
/*
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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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* switch.h - Cooperative VM context switch (FABRIC-3.md §XXVIII, Stage 2,
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* 2026-09-13).
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*
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* sk_vm_context_switch() suspends `from`'s execution exactly where it is
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* (mid-C-call-stack, on from's own native stack -- Stage 1) and resumes
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* `to` -- either for the first time ever (a synthesized initial frame,
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* entering sk_vm_switch_entry()) or exactly where `to` was itself last
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* switched out. Returns to the caller only once something later switches
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* back to `from` -- from from's own point of view, this call simply
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* takes a while to return, like any blocking call.
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*
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* Cooperative only: nothing here is interrupt-driven yet (that's Stage
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* 3), so this is safe to call only from ordinary FORTH word dispatch,
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* never from ISR context.
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*/
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#ifndef STARKERNEL_VM_SWITCH_H
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#define STARKERNEL_VM_SWITCH_H
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#ifdef __STARKERNEL__
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struct VM;
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int sk_vm_context_switch(struct VM *from, struct VM *to);
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/* FABRIC-3.md §XXVIII Stage 3 follow-on (2026-09-14): which VM is
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* currently physically running, tracked by the switch mechanism itself --
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* see switch.c's own doc comment on g_switch_current_vm for why this
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* exists instead of reusing vm_log_attributed_vm(). sk_vm_switch_set_
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* current() seeds the initial value (whoever is running before any
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* switch has ever happened) -- call once, at Stage 3 registration time. */
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struct VM *sk_vm_switch_current_vm(void);
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void sk_vm_switch_set_current(struct VM *vm);
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#endif /* __STARKERNEL__ */
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#endif /* STARKERNEL_VM_SWITCH_H */
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