Replaces the victim-thread-mutate-then-wait scheme for vsync / CP
interrupts with synchronous in-line dispatch on the coordinator host
thread. Mirrors canary's EmulateCPInterruptDPC -> Processor::Execute
path (kernel_state.cc:1370, processor.cc:413): pick a guest thread,
borrow its PpcContext, jam ISR PC + args in, run the interpreter
inline until LR_HALT_SENTINEL, restore the borrowed context.
Why: audit-059 measured gpu.interrupt.delivered{source=0} = 54 over
3.9 s vs canary's 4712 over 30 s. Per-second shortfall ~11×. Old
asynchronous LR-sentinel injection (try_inject_graphics_interrupt)
needed a Ready or Blocked guest thread to land on; once the Sylpheed
main thread and worker threads all idled post-boot, no victim was
available and every queued vsync got dropped. Host-driven dispatch
decouples delivery from guest-thread readiness.
Smoke test (lockstep): unchanged 54 — under current Sylpheed boot
trajectory the ticker is gated by guest-instruction progress, not
victim availability; lockstep stalls into idle-advance after ~5M
instructions of real work and the synthetic tick_vsync_instr stops
firing. Under --parallel (wallclock ticker) gpu.interrupt.delivered
climbs to ~1131 over a 128 s run, confirming the synchronous
dispatcher itself works as intended. Architectural piece is now in
place; raising the lockstep delivery rate requires ticking the
synthetic vsync inside coord_idle_advance, which is a separate
change.
Changes:
- crates/xenia-kernel/src/interrupts.rs: doc-comment update only.
SavedCallbackCtx + CALLBACK_STACK_PAD retained — the audio
callback path (audit-048) still uses the asynchronous LR-sentinel
inject on a dedicated per-client worker.
- crates/xenia-app/src/main.rs:
* dispatch_graphics_interrupts(kernel, mem, &mut stats,
&mut decode_cache, thunk_map): new fn. Drains the full FIFO per
call. Victim selection same shape (Ready preferred, else
Blocked, skip Idle/Exited/ServicingIrq), but the call is
synchronous - we run step_cached + import-thunk dispatch inline
on the borrowed ctx until pc == LR_HALT_SENTINEL.
MAX_INSTRS_PER_ISR = 1M safety budget.
* coord_pre_round: graphics-IRQ injection call removed. Audio
path unchanged (still calls try_inject_audio_callback).
* run_execution + run_execution_parallel: each now owns a
persistent isr_decode_cache and calls
dispatch_graphics_interrupts after coord_pre_round.
* try_inject_graphics_interrupt: deleted (118 LOC).
No new public APIs, no new dependencies, no changes to xenia-cpu.
Tests: workspace 765 passed / 0 failed / 4 ignored (parallel_stress
+ sylpheed_n50m, all gated). Kernel 127/127, app 5/5, cpu 288/288.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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