FABRIC.md: item 4.5d -- Finding 3 (muldiv64) root-caused and fixed via QEMU tracing, Finding 4 blocks

Used QEMU-side instrumentation (-d int tracing, plus a working chardev-based
monitor -- the older bareword -monitor syntax silently fails on QEMU
10.2.1) as directed. The PM Timer "stall" was never a hang: it was a #DE
divide error cascading to a triple fault, which -no-reboot converts into a
silent clean QEMU exit -- indistinguishable from a hang without tracing,
and why arch_relax() (solving a hang that didn't exist) had no effect.
Root cause and fix documented in full (also see commit b43e51a).

With the fix, amd64 boot at -O2 now proceeds far past the original stall --
through capsule birth and into Hermes's word registration -- before hitting
a second, different fault (Finding 4): a direct #GP at IDT index 32
(APIC_TIMER_VECTOR), not yet root-caused. Same silent-triple-fault-exit
shape, so this was very likely bundled into "the hang" before tracing
distinguished the two separate bugs.

-O2 reverted again (uncommitted); muldiv64's fix is kept, real and
independently verified at unchanged -O0 on all three architectures.
Routine three-arch artifacts from this session's verification runs
included.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

logs/20260811-114704/amd64/qemu-amd64-20260811-114704.log

@@ -0,0 +1,82 @@
+[=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 11:46:56
+
+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...