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LithosAnanake/disk/README.md
T
Robert Allan JamesandClaude Sonnet 5 148c4aa12c Fix silent disk overwrite of unrecognized Artemis disks
The generic block subsystem (blk_format_or_load_disk) auto-reformatted
any disk lacking its own low-level 'STFR' header at attach time, before
Artemis's Forth-level BLANK/LithosAnanke/Unrecognized classification
ever ran -- so ART-HALT-UNRECOG's "Disk preserved" message was false.

Split detection from commit: an unrecognized/blank disk is now left
PROVISIONAL (geometry computed in memory only, all writes refused)
until explicitly confirmed via the new blk_subsys_confirm_format() /
BLK-CONFIRM-FORMAT primitive. Artemis calls it from ART-FORMAT and
ART-RESUME, never from ART-HALT-UNRECOG.

Verified on amd64/aarch64/riscv64: parity intact (identical dict_hash),
normal recognized-disk resume + persist-read unaffected, and a
regenerated disk/artemis-unrecognized-test.img (the old copy had itself
been silently corrupted by this exact bug) now stays byte-for-byte
identical across a halted boot on amd64 and riscv64.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
2026-08-02 11:44:23 -04:00

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Markdown

# disk/
QEMU disk images used for Artemis (block-storage VM) persistence testing.
Mounted via `Makefile.starkernel`'s `ARTDISK` variable (default
`disk/artemis.img`) as a `virtio-blk-pci` device on all three
architectures' kernel QEMU boots — not `scripts/rundisk.sh`, which targets
a separate, currently-unused `disks/` (plural) directory for the *hosted*
VM's `--disk-img=` flag instead.
- `artemis.img` — standard Artemis persistence test disk. **Reformatted
2026-08-02**: this image had been stuck in a corrupted state (valid
`LithosAnanke` magic header, but data not matching what
`ART-READ-TEST` expects) since before this repo's own git history
begins (`git log` shows it already broken at the initial commit,
carried over from the pre-split monorepo). Chasing down the resulting
persistent `FAIL: persist-read` traced to the *data*, not the code —
the write→reboot→read round trip works correctly on a fresh image
(see `artemis-debug-roundtrip.img` below). Reformatted by blanking the
file and letting a normal boot format+write-test it; verified
`PASS: persist-read` on amd64, aarch64, and riscv64 against the same
image afterward (cross-arch resume, matching the arch-neutral on-disk
format `.claude/ARTEMIS.md` specifies).
- `artemis-debug-roundtrip.img` — round-trip regression fixture created
during that investigation. Known-good: format → self-test → write-test
→ reboot → resume → `PASS: persist-read`, confirmed 3 times in a row.
Keep this in a passing state; if a future change breaks it, that's a
real regression, not a stale-fixture artifact like `artemis.img` was.
- `artemis-persist-test.img` — persistence round-trip test image
(pre-existing; history/state not re-verified during the above
investigation).
- `artemis-poison.img` — a separate test image (exact scenario not
documented elsewhere in the repo as of this writing; name suggests an
adversarial/corruption test, not confirmed).
- `artemis-unrecognized-test.img` — exercises `ART-HALT-UNRECOG`
(`.claude/ARTEMIS.md` acceptance criterion #6). **Regenerated
2026-08-02**: the previous copy of this file had itself been silently
reformatted by a since-fixed bug in the *generic* block subsystem
(`src/block_subsystem.c`) — it carried a valid low-level `'STFR'`/v2
header despite being meant to represent foreign disk content, direct
forensic evidence of the bug described in `.claude/ARTEMIS.md`'s
Build Status item 6. Regenerated as 30MB of a repeating
`POISON-UNRECOGNIZED-DISK-TEST-FIXTURE--NOT-BLANK-NOT-STFR-NOT-ARTEMIS--`
ASCII pattern — deliberately neither blank, nor the block subsystem's
own `'STFR'` magic, nor Artemis's `"ARTEMIS\0"` marker. Verified on
amd64 and riscv64 post-fix: boot correctly halts
(`ARTEMIS HALT: unrecognized disk content`) and the file's sha256 is
now byte-for-byte identical before and after boot. Keep this fixture
in this poisoned state — if a future change makes its sha256 change
across a boot, that is exactly the regression this fixture exists to
catch.
Note on incidental header churn: `artemis.img` picks up a few changed
header bytes on every ordinary boot even though no user data changes —
`blk_subsys_attach_device()` always records a fresh `mounted_time` on a
successfully recognized disk, which gets flushed at shutdown. This is
expected bookkeeping, not a bug; revert it before committing rather than
carrying timestamp noise in git history.
These are regenerable QEMU raw disk images, not source — see
`.claude/ARTEMIS.md` for the storage model they exercise.