docs/observations/2026-08-09-self-init-iso-cdrom.md

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# Observation — self-init hybrid ISO / GRUB / serial (x86_64)

| Field | Value |
|---|---|
| Date (UTC) | 2026-08-10 (local 2026-08-09 evening America/Chicago) |
| Profile | `self-init` |
| Arch | x86_64 |
| Path | `iso-cdrom` (full chain: SeaBIOS → El Torito → GRUB 2.06 → kernel → initramfs → `/init` → phase walk) |
| Emulator | QEMU 10.2.2 `qemu-system-x86_64` |
| Machine / memory | q35 / 512 MiB |
| Artifact path | `build-out/artifacts/numericalos-self-init.iso` |
| Initramfs sha256 | `b78ca437df96d8ff1114e313873728af01339cc6ff989fec7c4268107368029d` (`numericalos-self-init.cpio.gz`) |
| ISO sha256 | `d93d0da251558e6a19f83ddb7ca1bff89f7d2adb2b980ed60716f7fea2319044` |
| Floor name / sha256 | `numos-floor` / `6e123e7f3202a8c1e9b1f94d8941580a25135382b99e8d3e34fb858bba311348` |
| Kernel source | Debian `linux-image-6.1.0-50-amd64` (local `vmlinuz`; sha256 `d8808aa4ca188560da1e6d749dcb930c87a5fd8b11ebff1f3fa6d728af35203d`) |
| Build id (CF/R2) | remaster of earlier CF hybrid `20260809192728-2c4babdd` / `numericalos-x86_64.iso` via MSYS `xorriso` in-place map (self-init initrd + serial GRUB) |
| Verdict | **PASS** |
| `boot complete` line | `numos: boot complete degraded=0` |
| Steady state? | yes |
| Degrades / HALTs | none |
| Serial log path | `build-out/artifacts/boot-self-init-iso.log` |
| Observer | session Grok Build / NumericalOS praxis Phase A2 |

## Verbatim `numos:` lines

```
numos: arch x86_64
numos: init numinit.sh (shell floor)
numos: on-disk /opt/numericalos/numinit.sh
numos: state verified
numos: boot complete degraded=0
numos: steady state entered
```

## Chain evidence (serial)

- SeaBIOS (QEMU prebuilt)
- `Booting from DVD/CD...`
- GNU GRUB 2.06 menu: default `NumericalOS self-init (serial)`
- Kernel command line (verbatim from dmesg):  
  `BOOT_IMAGE=/boot/vmlinuz console=ttyS0,115200n8 earlyprintk=serial,ttyS0,115200 NUMOS_OFFLINE=1 NUMOS_PREFIX=/opt/numericalos NUMOS_STATE=/etc/numos.state NUMOS_LIB=/lib`
- `Run /init as init process`
- then the `numos:` lines above

## How the ISO was produced (honest)

1. Base hybrid ISO from Cloudflare builder history (`numericalos-x86_64.iso`, `file` reports bootable GRUB2 El Torito).
2. Local MSYS2 tools: `cpio`, `xorriso` (no `grub-mkrescue` package available).
3. In-place remaster (preserve El Torito): copy base ISO, then  
   `xorriso -dev … -boot_image any keep -map` for `/boot/initramfs.cpio.gz`, `/boot/vmlinuz`, `/boot/grub/grub.cfg`.
4. GRUB default = serial entry; **only** `console=ttyS0,115200n8` on that entry (see Notes).

## Notes — what is *not* proven

- Not metal. Not USB stick on hardware.
- Not non-x86_64.
- Not a brand-new CF Sandbox rebuild in this session (CF `POST /build` still flaky: SandboxError HTTP 500 / isolate 1101 residual).
- Not fleet profile on ISO path.
- Clone-to-new-file remaster (`-indev`/`-outdev`) **broke** El Torito in this environment; in-place `-dev` update was required.
- Earlier failed ISO serial observation: listing both `console=ttyS0` and `console=tty0` made **tty0 last**, so `/dev/console` was VGA and userspace `numos:` lines did not appear on the serial capture despite a working `/init`.