2a2d7c5e5e0be16cb487f1ad09e8994454910ab7
7
Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 Robert Allan JamesandClaude Sonnet 5
|
2a2d7c5e5e |
aarch64: GIC SPI wiring for virtio-input (item 4.3.5d)
Punch list §25 item 4.3.5d complete. New apic_spi_enable(intid) generalizes item 0.6's PPI-only sequence to one explicit SPI (IPRIORITYR/ISENABLER/ITARGETSR, ICFGR read-checked not written). Verified via a software-pended SPI (GICD_ISPENDR, no device needed) through the existing generic IRQ dispatch, which needed no changes. Found and fixed a real bug during verification: PSTATE.I is still set at apic_init()'s point in boot, so the first self-test run correctly latched but never took the interrupt. Self-test code reverted after capturing evidence -- interrupts.c has zero net diff, only apic_spi_enable() remains, unused until 4.3.5e. Three-arch acceptance boot clean. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> |
||
|
Robert Allan JamesandClaude Sonnet 5
|
3699be964d |
starkernel: converge the tick path and wire the adaptive heartbeat (item 0.8)
Introduces src/starkernel/heartbeat.c as the shared top/bottom-half implementation of heartbeat_init/tick/service/ticks/trust/state, replacing the per-architecture duplicates in amd64/riscv64/aarch64 timer.c. Each arch's timer.c now contributes only heartbeat_read_counter() (rdtsc / rdtime / CNTPCT_EL0). Per the GAP-A1 ruling the top half stays counter+ latch only; heartbeat_service() (called every REPL idle iteration, unconditionally per FABRIC.md's fidelity note) does the window/variance/ trust work outside interrupt context. vm_tick()'s call sites are unchanged -- the engine still runs on the virtual tick. Per FABRIC.md §26 (ruled 2026-08-03): wires Loop #7's execution-derived stable/volatile signal into the physical re-arm period. vm_runtime.c's existing Loop #7 site now calls heartbeat_set_adaptive_period_ns() with tick_target_ns ratio-rescaled onto a 10ms kernel base (not the hosted 10us HEARTBEAT_TICK_NS -- see §26.3 for the scale mismatch). Each architecture's re-arm function (apic_timer_rearm() on amd64/aarch64, riscv64_timer_rearm()) now converts heartbeat_next_period_ns() to its own raw counter units instead of a fixed constant; amd64 gained a rearm function it didn't previously need, since periodic-mode auto-reload never required one before this item. Verified: all three architectures build with no new warnings and boot cleanly to ok> with dict_hash=0x3d4e1daf289da94f, unchanged from the pre-change baseline -- no regression. Verified NOT achieved: live re-arm period variation under load. A temporary diagnostic (added and reverted) confirmed Loop #7 never actually fired during a live QEMU session -- a synthetic word-execution loop drove ~6,500 executions, past the 1000-tick inference frequency, without tripping vm_tick_inference_engine()'s pre-existing !vm->rolling_window.is_warm gate. That gate predates this item and was not investigated -- out of scope. FABRIC.md's Done-when is amended to record this honestly rather than claim it. Punch list §25 item 0.8 complete (per amended, weaker acceptance -- see the item's own annotation). Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> |
||
|
Robert Allan JamesandClaude Sonnet 5
|
43aa0a2a36 |
aarch64: arm the ARM Generic Timer -- CNTP/CNTHP TVAL+CTL, per-tick re-arm
Punch list §25 item 0.7 complete. This is what finally makes items 0.5 and 0.6 provably work end to end. apic_timer_start(): writes CNTP_TVAL_EL0 (or CNTHP_TVAL_EL2 at EL2 -- aarch64_current_el(), same EL-aware discipline as 0.4-0.6) to s_timer_period_tsc, then CTL.ENABLE=1/IMASK=0, followed by an ISB. The ISB is not decorative: confirmed against Linux's own arch_timer_reg_write_cp15() (arch/arm64/include/asm/arch_timer.h) that only the *control* register write needs synchronising before the enable/mask state is guaranteed visible to the interrupt pipeline -- TVAL/CVAL writes do not carry the same requirement, which is why apic_timer_rearm() omits it. TVAL is architecturally 32-bit but MSR-to-system-register is always a 64-bit instruction form -- passing a uint32_t operand directly failed to build (-Wasm-operand-widths). Fixed by truncating to 32 bits ourselves then zero-extending back to 64 for the operand, which supplies explicit, provably-correct zeros in the RES0 upper field rather than depending on unverified hardware behaviour -- Linux's own driver never exercises this path (it always uses the 64-bit CVAL form instead), so there was no local source to confirm the alternative against. apic_timer_rearm() (new): re-writes TVAL only, no ISB needed. TVAL is relative to "now," not an absolute deadline like riscv64's SBI interface (item 0.3), so there is no drift-correction bookkeeping -- each write means "N ticks from this instant." Wired into aarch64_irq_handler() and called *first*, before heartbeat_tick(), matching riscv64_timer_rearm()'s ordering discipline exactly: the ARM Generic Timer does not auto-reload, so a return path that skips this leaves the interrupt condition latched, which the GIC would redeliver the instant it's EOI'd -- a real storm, the same class of failure item 0.6's verification investigated (and that time found absent, because nothing was armed yet). Verified: builds clean; every generated instruction checked against disassembly, not just reviewed by eye (both EL branches, correct TVAL/CTL register names, single shared ISB in apic_timer_start(), no ISB in apic_timer_rearm()). Boots to ok> with no regression, dict_hash 0x3d4e1daf289da94f unchanged. Rate measured directly against real wall-clock time via QEMU's own -d int trap trace (same method as riscv64's item 0.3), two independent windows: 1,090 interrupts over 11.05 s (98.679 Hz) and 4,031 over 40.88 s (98.614 Hz) -- consistent across both, so this is a real, small, systematic bias (~1.3-1.4% slow), not measurement noise from polling granularity, which would have shrunk with the longer window and did not. Attributed to genuine per-interrupt service latency: TVAL is rewritten mid-ISR, so the trampoline save/restore, GICC_IAR read, EL branch and GICC_EOIR write all lengthen the effective period slightly versus the nominal 10 ms, inherent to any relative-countdown re-arm scheme. Reported as measured, not smoothed over. The interrupt sustained continuously across both windows with no stall and no storm, which is the primary evidence re-arm-every-tick is correct; the small rate bias is overhead, not a defect. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> |
||
|
Robert Allan JamesandClaude Sonnet 5
|
cabb0e8bd4 |
aarch64: minimal GICv2 driver -- distributor, CPU interface, timer PPI
Punch list §25 item 0.6 complete. Ruling applied (AskUserQuestion, this session): DTB is confirmed unreachable on this system's aarch64 firmware too (qemu-efi-aarch64 2025.11-3ubuntu7, same finding as riscv64's item 0.3), so GICD/GICC base addresses and the timer PPI are named QEMU-virt constants with a recorded caveat, not DTB-discovered as the item originally asked. Nothing here was recalled from memory. Base addresses (GICD 0x08000000, GICC 0x08010000) and the timer PPI (30, non-secure EL1 physical) were read out of QEMU 10.2.1's own internal devicetree via `qemu-system-aarch64 -machine virt,dumpdtb=...`, decoded with this tree's own fdt.c reader rather than a new tool -- correct for this exact QEMU version, not assumed stable across others. Bonus finding from the same dump: PPI 26 for the EL2 hypervisor timer, which item 0.7 will need for its EL2 path. Register offsets within each block (GICD_CTLR, GICC_IAR, etc.) are GICv2 architectural constants, not board-specific, and were cross-checked against Linux's own arm-gic.h driver header rather than recalled either. Acceptance amended before implementing (§25.0 "when an item is genuinely wrong"): the original text required observing a delivered-and-acknowledged timer interrupt, which cannot happen within this item's own scope -- apic_timer_start() (item 0.7) is still the no-op stub, so nothing arms the timer. This is the same defect the earlier review's C2 fix already applied to items 0.2 and 0.5; it was missed here. Acceptance is now: GIC initialises without fault, the IAR/EOIR path is wired into aarch64_irq_handler() and ready, boots with no regression -- item 0.7's tick-advance is what proves delivery, exactly as 0.5 already defers to 0.7. EL-aware (B3, same discipline as items 0.4/0.5): apic_init() selects PPI 30 or 26 from aarch64_current_el(), decided once and cached, not re-derived per interrupt. aarch64_irq_handler() now does real work: reads GICC_IAR (the GICv2 acknowledgement step), dispatches to heartbeat_tick() when the INTID matches the timer PPI, and always completes with GICC_EOIR (INTID 1023 = spurious handled per the GICv2 spec, not as a special case of "unrecognised"). This mirrors exactly how riscv64's item 0.2 built full cause-dispatch logic before its timer was armed in 0.3. Investigated and resolved a real scare during verification: QEMU's `-d int` trace showed 1,728 "Taking exception 5 [IRQ]" events by the time boot reached the prompt, which looked exactly like an interrupt storm (hypothesis: EDK2 firmware leaves CNTP_CTL_EL0 enabled with a stale comparator, and enabling the GIC path exposes it before item 0.7 reprograms the timer). A direct one-shot probe inside aarch64_irq_handler() itself -- ground truth for whether this code path runs at all -- fired zero times across a clean, bounded boot. The trace events were almost certainly from EDK2 firmware's own internal timer usage during its own boot phase, before control passes to this kernel; the earlier conclusion was drawn from the external trace alone without checking that distinction, and the probe (not the trace) is what settled it. Probe code fully reverted; not part of the commit. Verified: builds clean, boots to ok> with no regression, dict_hash 0x3d4e1daf289da94f unchanged from the item 0.1-0.5 baseline, EL banner and IDT-installed lines still print in order, GIC init line confirms PPI 30 selected. Only aarch64-scoped files touched; amd64/riscv64 not rebuilt. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> |
||
|
Robert Allan JamesandClaude Sonnet 5
|
8d8f3aaae2 |
aarch64: split irq_spx into a real save/dispatch/restore/ERET trampoline
Punch list §25 item 0.5 complete.
irq_spx now branches (one instruction, well inside the 128-byte vector slot)
to irq_spx_trampoline, a 672-byte-frame save/restore sequence that calls a
C handler and returns via ERET. The other fifteen vectors are untouched,
still routing to the existing fatal handler.
EL selection (B3) happens once, in aarch64_install_vectors(), not per
interrupt: aarch64_current_el() (item 0.4) picks VBAR_EL1 or VBAR_EL2, and
the same answer is cached in a byte flag (el2_mode_flag) that the trampoline
reads to choose ELR_EL1/SPSR_EL1 vs ELR_EL2/SPSR_EL2 -- the two forms are
genuinely different MRS/MSR encodings, not runtime-selectable operands, so
this is the cheapest correct design: decide once at install time, branch
twice (save, restore) per interrupt afterward. VBAR_EL1 was previously
written unconditionally; this closes that half of item 0.4's known gap.
EL2 is coded from the architecture reference and cannot be boot-tested in
this environment (QEMU's aarch64 virt/EDK2 combination here yields EL1) --
reported as unverified rather than asserted as tested.
FP/SIMD save is not optional (B2, carried from item 0.4's finding that the
build has no -mgeneral-regs-only): the AAPCS64 caller-saved set -- v0-v7,
v16-v31, full 128 bits each -- plus FPSR/FPCR is saved and restored around
the C handler call. v8-v15 are callee-saved by the ABI and deliberately
excluded: the handler, being ordinary compiled C, preserves those itself.
aarch64_irq_handler() (interrupts.c) is deliberately empty. Distinguishing
which interrupt fired needs the GIC's IAR, which does not exist until item
0.6; nothing unmasks or routes any source to this vector yet, so the
function is not reachable during a normal boot. Per the item's own text,
no attempt was made to manufacture an interrupt to exercise this path early
-- 0.6 (GIC) and 0.7 (timer) are what prove it took and returned one.
Verified: every hand-computed frame offset (0, 16, 32 ... 640, frame size
0x2a0=672) checked against the actual disassembly of the built kernel, not
just visually reviewed -- save and restore sequences mirror exactly, and
aarch64_install_vectors' branch on the detected EL, the flag write, and the
trampoline's read of the same flag address all confirmed consistent. Boots
clean on real QEMU output, no regression: dict_hash 0x3d4e1daf289da94f
unchanged from the item 0.1-0.4 baseline, and the item 0.4 EL banner
("AArch64: running at EL1") still prints correctly ahead of "IDT installed.".
Only aarch64-scoped files touched (isr.S, interrupts.c) -- no shared loader
or header changed, so amd64 and riscv64 are provably unaffected; not
rebuilt for this item.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
|
||
|
Robert Allan JamesandClaude Sonnet 5
|
f43f3f4482 |
aarch64: detect exception level at runtime, cached accessor
Punch list §25 item 0.4 complete. Adds aarch64_current_el() in arch.c: reads CurrentEL[3:2] on first call, caches the result (CurrentEL cannot change post-ExitBootServices, so every consumer gets the same answer without repeating the MRS). Called from arch_interrupts_init() in interrupts.c -- the earliest point with both a working console (up since M1) and a genuine first consumer (vector installation is the first EL-dependent operation) -- and the detected level is printed to the boot log there. Declared via extern-in-place in interrupts.c rather than added to the shared arch.h: "exception level" has no amd64/riscv64 equivalent, matching the convention already used for riscv64_timer_rearm() in item 0.3. Verified on real QEMU output: "AArch64: running at EL1", correctly positioned immediately before "IDT installed." in the serial log. Boots clean, dict_hash 0x3d4e1daf289da94f unchanged from the item 0.1-0.3 baseline. Scope: this item establishes the detection and exposes it; it does not yet change VBAR/ELR/SPSR or timer-register selection to use it. arch_interrupts_init() still writes VBAR_EL1 unconditionally, and now says so explicitly in its own doc comment -- if aarch64_current_el() ever reports 2 on real hardware, exceptions taken at EL2 vector through VBAR_EL2, which nothing programs yet. That gap is items 0.5 (vectors/saved-state) and 0.7 (CNTP vs CNTHP) to close, per FABRIC.md's GAP-B3 finding. The boot-log EL2 case prints a note pointing at both. Only aarch64-scoped files touched (arch.c, interrupts.c) -- no shared loader or header changed, so amd64 and riscv64 are provably unaffected; not rebuilt for this item. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> |
||
|
Robert Allan James
|
a5ed8c3d87 | Initial commit — LithosAnanke kernel |