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>

This commit is contained in:

Robert Allan James

2026-08-11 12:17:23 -04:00

co-authored by

Claude Sonnet 5

parent b43e51a95d

commit 1c5e926c3f

18 changed files with 104344 additions and 77 deletions

									
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				# Capsule Block Manifest — Auto-generated

				<!-- Generated by mkcapsule --manifest  2026-08-11T15:34:05Z -->

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				<!-- DO NOT EDIT — re-run mkcapsule --manifest to refresh.  -->

				<!-- Hand-written justifications and immutability notes live  -->

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