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FABRIC.md: item 4.5d -- arch_relax() tested against the PM Timer stall, disproven

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Follow-up probing narrowed Finding 3's behavior (inconsistent stall point
run-to-run: sometimes reaches iters=1000/delta=951 before stopping,
sometimes never gets past iters=0 even after a 400-second bounded wait) but
didn't pin the mechanism.

Tested the strongest available hypothesis: single-threaded TCG scheduling
starvation from an -O2-tightened spin loop, based on a real precedent --
calibrate_apic_timer() (apic.c) already calls arch_relax() every iteration
of its own spin-wait; calibrate_tsc_with_pmtimer() never had it. Added the
same call, matching that precedent exactly. Result: no change, same exact
stall point on a fresh 60-second bounded wait. Reverted.

Stopping here per this document's own §25.0 rule 5 -- root-causing further
needs either deeper TCG/QEMU internals knowledge or a different diagnostic
approach (host-side instrumentation) than another guess-and-check pass.
Makefile.starkernel and timer.c both back to committed -O0 state, confirmed
booting clean.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
This commit is contained in:
Robert Allan James
2026-08-11 11:35:09 -04:00
co-authored by Claude Sonnet 5
parent 7df2e1bae3
commit dd09de65f5
10 changed files with 18655 additions and 37 deletions
Download Patch File Download Diff File Expand all files Collapse all files
logs/20260811-111827/amd64/qemu-amd64-20260811-111827.log
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[=3hBdsDxe: loading Boot0002 "UEFI QEMU DVD-ROM QM00005 " from PciRoot(0x0)/Pci(0x1F,0x2)/Sata(0x2,0xFFFF,0x0)
BdsDxe: starting Boot0002 "UEFI QEMU DVD-ROM QM00005 " from PciRoot(0x0)/Pci(0x1F,0x2)/Sata(0x2,0xFFFF,0x0)
[=3hStarKernel UEFI Loader
Loading kernel from ESP...
[CKPT 001] Entered efi_main - ConOut live
RAW SERIAL UP
[CKPT 002] Serial (COM1) initialized
Monolithic build - kernel linked directly
Collecting boot information...
CmdLine: parsed OK
[CKPT 004] Command line parsed
[CKPT 005] Kernel stack allocation decided
[CKPT 006] Boot info collected (ACPI table located)
GOP: linear framebuffer found
[CKPT 007] GOP: linear framebuffer found
[CKPT 008] About to enter ExitBootServices retry loop
EBS...
EBS OK
Calling kernel_main (monolithic)...
_____ _ _ __ _
/ ____| | | |/ / | |
| (___ | |_ __ _ _ __| ' / ___ _ __ _ __ ___| |
\___ \| __/ _` | '__| < / _ \ '__| '_ \ / _ \ |
____) | || (_| | | | . \ __/ | | | | | __/ |
|_____/ \__\__,_|_| |_|\_\___|_| |_| |_|\___|_|
LithosAnanke v1.5.4
Architecture: amd64
Build: Aug 11 2026 11:18:21
UEFI BootServices: EXITED
=== StarKernel Boot Information ===
Memory map entries: 113
Total memory: 1023 MB
Usable memory: 967 MB
===================================
PMM initialized.
PMM statistics:
Total pages: 248976
Free pages : 247453
Used pages : 1523
Total MB : 972
Free MB : 966
Used MB : 5
VMM initialized (mapped RAM, CR3 switched)
VMM initialized (mapped RAM, CR3 switched)
VMM self-test: mapped OK at 0xffff800000000000
VMM self-test complete.
IDT installed.
APIC: init...
APIC: IA32_APIC_BASE MSR=0x00000000fee00900
APIC: stale-ISR drain: 0 EOI(s) issued
APIC: initialized (xAPIC MMIO, TPR=0, SIVR=0x1FF, EOI-clear)
APIC: init done
I/O APIC: init...
I/O APIC: base=0xfec00000, gsi_base=0, overrides=5
override: source=00 gsi=2 flags=0x0000
override: source=05 gsi=5 flags=0x000d
override: source=09 gsi=9 flags=0x000d
override: source=0a gsi=10 flags=0x000d
override: source=0b gsi=11 flags=0x000d
i8042: keyboard ACKed enable-scanning
i8042: IRQ1 enabled in controller config byte
I/O APIC: keyboard IRQ1 routed (masked)
Timer: init...
Timer: init start
Timer: PM_TMR_BLK discovered from FADT at port 1544
Timer: VM mode detected (hypervisor present).
Timer: HPET calibration disabled (VM-exit MMIO would poison timing).
Timer: WARNING: invariant TSC not present under hypervisor.
Timer: continuing in RELATIVE mode (no determinism guarantees).
Timer: RDTSCP not present; using RDTSC (less serialized).
Timer: CPUID frequency unavailable; trying PM Timer...
PMPROBE iters=0 delta=67 tsc_elapsed=84378
PMPROBE iters=1000 delta=951 tsc_elapsed=546483
logs/20260811-112103/amd64/qemu-amd64-20260811-112103.log
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[=3hBdsDxe: loading Boot0002 "UEFI QEMU DVD-ROM QM00005 " from PciRoot(0x0)/Pci(0x1F,0x2)/Sata(0x2,0xFFFF,0x0)
BdsDxe: starting Boot0002 "UEFI QEMU DVD-ROM QM00005 " from PciRoot(0x0)/Pci(0x1F,0x2)/Sata(0x2,0xFFFF,0x0)
[=3hStarKernel UEFI Loader
Loading kernel from ESP...
[CKPT 001] Entered efi_main - ConOut live
RAW SERIAL UP
[CKPT 002] Serial (COM1) initialized
Monolithic build - kernel linked directly
Collecting boot information...
CmdLine: parsed OK
[CKPT 004] Command line parsed
[CKPT 005] Kernel stack allocation decided
[CKPT 006] Boot info collected (ACPI table located)
GOP: linear framebuffer found
[CKPT 007] GOP: linear framebuffer found
[CKPT 008] About to enter ExitBootServices retry loop
EBS...
EBS OK
Calling kernel_main (monolithic)...
_____ _ _ __ _
/ ____| | | |/ / | |
| (___ | |_ __ _ _ __| ' / ___ _ __ _ __ ___| |
\___ \| __/ _` | '__| < / _ \ '__| '_ \ / _ \ |
____) | || (_| | | | . \ __/ | | | | | __/ |
|_____/ \__\__,_|_| |_|\_\___|_| |_| |_|\___|_|
LithosAnanke v1.5.4
Architecture: amd64
Build: Aug 11 2026 11:20:23
UEFI BootServices: EXITED
=== StarKernel Boot Information ===
Memory map entries: 113
Total memory: 1023 MB
Usable memory: 967 MB
===================================
PMM initialized.
PMM statistics:
Total pages: 248976
Free pages : 247453
Used pages : 1523
Total MB : 972
Free MB : 966
Used MB : 5
VMM initialized (mapped RAM, CR3 switched)
VMM initialized (mapped RAM, CR3 switched)
VMM self-test: mapped OK at 0xffff800000000000
VMM self-test complete.
IDT installed.
APIC: init...
APIC: IA32_APIC_BASE MSR=0x00000000fee00900
APIC: stale-ISR drain: 0 EOI(s) issued
APIC: initialized (xAPIC MMIO, TPR=0, SIVR=0x1FF, EOI-clear)
APIC: init done
I/O APIC: init...
I/O APIC: base=0xfec00000, gsi_base=0, overrides=5
override: source=00 gsi=2 flags=0x0000
override: source=05 gsi=5 flags=0x000d
override: source=09 gsi=9 flags=0x000d
override: source=0a gsi=10 flags=0x000d
override: source=0b gsi=11 flags=0x000d
i8042: keyboard ACKed enable-scanning
i8042: IRQ1 enabled in controller config byte
I/O APIC: keyboard IRQ1 routed (masked)
Timer: init...
Timer: init start
Timer: PM_TMR_BLK discovered from FADT at port 1544
Timer: VM mode detected (hypervisor present).
Timer: HPET calibration disabled (VM-exit MMIO would poison timing).
Timer: WARNING: invariant TSC not present under hypervisor.
Timer: continuing in RELATIVE mode (no determinism guarantees).
Timer: RDTSCP not present; using RDTSC (less serialized).
Timer: CPUID frequency unavailable; trying PM Timer...
PMPROBE-far iters=0 delta=65 tsc_elapsed=96957
logs/20260811-112231/amd64/qemu-amd64-20260811-112231.log
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[=3hBdsDxe: loading Boot0002 "UEFI QEMU DVD-ROM QM00005 " from PciRoot(0x0)/Pci(0x1F,0x2)/Sata(0x2,0xFFFF,0x0)
BdsDxe: starting Boot0002 "UEFI QEMU DVD-ROM QM00005 " from PciRoot(0x0)/Pci(0x1F,0x2)/Sata(0x2,0xFFFF,0x0)
[=3hStarKernel UEFI Loader
Loading kernel from ESP...
[CKPT 001] Entered efi_main - ConOut live
RAW SERIAL UP
[CKPT 002] Serial (COM1) initialized
Monolithic build - kernel linked directly
Collecting boot information...
CmdLine: parsed OK
[CKPT 004] Command line parsed
[CKPT 005] Kernel stack allocation decided
[CKPT 006] Boot info collected (ACPI table located)
GOP: linear framebuffer found
[CKPT 007] GOP: linear framebuffer found
[CKPT 008] About to enter ExitBootServices retry loop
EBS...
EBS OK
Calling kernel_main (monolithic)...
_____ _ _ __ _
/ ____| | | |/ / | |
| (___ | |_ __ _ _ __| ' / ___ _ __ _ __ ___| |
\___ \| __/ _` | '__| < / _ \ '__| '_ \ / _ \ |
____) | || (_| | | | . \ __/ | | | | | __/ |
|_____/ \__\__,_|_| |_|\_\___|_| |_| |_|\___|_|
LithosAnanke v1.5.4
Architecture: amd64
Build: Aug 11 2026 11:20:23
UEFI BootServices: EXITED
=== StarKernel Boot Information ===
Memory map entries: 113
Total memory: 1023 MB
Usable memory: 967 MB
===================================
PMM initialized.
PMM statistics:
Total pages: 248976
Free pages : 247453
Used pages : 1523
Total MB : 972
Free MB : 966
Used MB : 5
VMM initialized (mapped RAM, CR3 switched)
VMM initialized (mapped RAM, CR3 switched)
VMM self-test: mapped OK at 0xffff800000000000
VMM self-test complete.
IDT installed.
APIC: init...
APIC: IA32_APIC_BASE MSR=0x00000000fee00900
APIC: stale-ISR drain: 0 EOI(s) issued
APIC: initialized (xAPIC MMIO, TPR=0, SIVR=0x1FF, EOI-clear)
APIC: init done
I/O APIC: init...
I/O APIC: base=0xfec00000, gsi_base=0, overrides=5
override: source=00 gsi=2 flags=0x0000
override: source=05 gsi=5 flags=0x000d
override: source=09 gsi=9 flags=0x000d
override: source=0a gsi=10 flags=0x000d
override: source=0b gsi=11 flags=0x000d
i8042: keyboard ACKed enable-scanning
i8042: IRQ1 enabled in controller config byte
I/O APIC: keyboard IRQ1 routed (masked)
Timer: init...
Timer: init start
Timer: PM_TMR_BLK discovered from FADT at port 1544
Timer: VM mode detected (hypervisor present).
Timer: HPET calibration disabled (VM-exit MMIO would poison timing).
Timer: WARNING: invariant TSC not present under hypervisor.
Timer: continuing in RELATIVE mode (no determinism guarantees).
Timer: RDTSCP not present; using RDTSC (less serialized).
Timer: CPUID frequency unavailable; trying PM Timer...
PMPROBE-far iters=0 delta=65 tsc_elapsed=90510
logs/20260811-113139/amd64/qemu-amd64-20260811-113139.log
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[=3hBdsDxe: loading Boot0002 "UEFI QEMU DVD-ROM QM00005 " from PciRoot(0x0)/Pci(0x1F,0x2)/Sata(0x2,0xFFFF,0x0)
BdsDxe: starting Boot0002 "UEFI QEMU DVD-ROM QM00005 " from PciRoot(0x0)/Pci(0x1F,0x2)/Sata(0x2,0xFFFF,0x0)
[=3hStarKernel UEFI Loader
Loading kernel from ESP...
[CKPT 001] Entered efi_main - ConOut live
RAW SERIAL UP
[CKPT 002] Serial (COM1) initialized
Monolithic build - kernel linked directly
Collecting boot information...
CmdLine: parsed OK
[CKPT 004] Command line parsed
[CKPT 005] Kernel stack allocation decided
[CKPT 006] Boot info collected (ACPI table located)
GOP: linear framebuffer found
[CKPT 007] GOP: linear framebuffer found
[CKPT 008] About to enter ExitBootServices retry loop
EBS...
EBS OK
Calling kernel_main (monolithic)...
_____ _ _ __ _
/ ____| | | |/ / | |
| (___ | |_ __ _ _ __| ' / ___ _ __ _ __ ___| |
\___ \| __/ _` | '__| < / _ \ '__| '_ \ / _ \ |
____) | || (_| | | | . \ __/ | | | | | __/ |
|_____/ \__\__,_|_| |_|\_\___|_| |_| |_|\___|_|
LithosAnanke v1.5.4
Architecture: amd64
Build: Aug 11 2026 11:31:34
UEFI BootServices: EXITED
=== StarKernel Boot Information ===
Memory map entries: 113
Total memory: 1023 MB
Usable memory: 967 MB
===================================
PMM initialized.
PMM statistics:
Total pages: 248976
Free pages : 247453
Used pages : 1523
Total MB : 972
Free MB : 966
Used MB : 5
VMM initialized (mapped RAM, CR3 switched)
VMM initialized (mapped RAM, CR3 switched)
VMM self-test: mapped OK at 0xffff800000000000
VMM self-test complete.
IDT installed.
APIC: init...
APIC: IA32_APIC_BASE MSR=0x00000000fee00900
APIC: stale-ISR drain: 0 EOI(s) issued
APIC: initialized (xAPIC MMIO, TPR=0, SIVR=0x1FF, EOI-clear)
APIC: init done
I/O APIC: init...
I/O APIC: base=0xfec00000, gsi_base=0, overrides=5
override: source=00 gsi=2 flags=0x0000
override: source=05 gsi=5 flags=0x000d
override: source=09 gsi=9 flags=0x000d
override: source=0a gsi=10 flags=0x000d
override: source=0b gsi=11 flags=0x000d
i8042: keyboard ACKed enable-scanning
i8042: IRQ1 enabled in controller config byte
I/O APIC: keyboard IRQ1 routed (masked)
Timer: init...
Timer: init start
Timer: PM_TMR_BLK discovered from FADT at port 1544
Timer: VM mode detected (hypervisor present).
Timer: HPET calibration disabled (VM-exit MMIO would poison timing).
Timer: WARNING: invariant TSC not present under hypervisor.
Timer: continuing in RELATIVE mode (no determinism guarantees).
Timer: RDTSCP not present; using RDTSC (less serialized).
Timer: CPUID frequency unavailable; trying PM Timer...
logs/20260811-113405/amd64/qemu-amd64-20260811-113405.log
+18140
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