<!-- Status: parallel KernelSU track — see docs/007-parallel-on-009.md -->

> **Status: parallel KernelSU / SusFS track** (kept). Bridge to current Magisk ROM: [`007-parallel-on-009.md`](007-parallel-on-009.md). Magisk ship resume: [`009-handoff-20261008.md`](009-handoff-20261008.md).

# Debug boot — freeze on panic (photo / dump)

Normal sunfish kernel: `CONFIG_PANIC_TIMEOUT=5` + often
`CONFIG_QCOM_FORCE_WDOG_BITE_ON_PANIC` → reboot in seconds. Console is
**UART only** (`console=ttyMSM0`); `# CONFIG_VT is not set` → **no Oops text
on the phone display** (you only see the Google logo loop).

## What a “debug boot” must include (owner)

For a useful photo, **both** are required — freeze alone is not enough:

1. **Freeze:** `CONFIG_PANIC_TIMEOUT=0` + cmdline `panic=0`; disable
   `CONFIG_QCOM_FORCE_WDOG_BITE_ON_PANIC` so it does not reboot in 5s.
2. **On-screen console:** `CONFIG_VT` + `CONFIG_FRAMEBUFFER_CONSOLE` (+
   `console=tty0` in cmdline). Without this, you only see the Google logo.

| Goal | Mechanism | Photo-able? |
|------|-----------|-------------|
| Stop reboot loop | `panic=0` / `PANIC_TIMEOUT=0`, no wdog-bite-on-panic | Logo freezes only |
| Oops on screen | VT + FRAMEBUFFER_CONSOLE + `console=tty0` | Yes if panic after FB; early may still be logo |
| Dump after hang | Freeze + penúltimo + immediate `klog`/`logfs` dd | Not a photo |

Use **only on LAB**, SusFS/debug trials. Never ship as daily boot.
Next SusFS debug build after the sigfix trial must enable **both**.

## Host recipe (LAB SusFS debug boot)

1. Defconfig fragment (or temporary edits) on `rom-dev01`:

```text
CONFIG_PANIC_TIMEOUT=0
# CONFIG_QCOM_FORCE_WDOG_BITE_ON_PANIC is not set
# optional on-screen console (experimental on Pixel 4.14):
CONFIG_VT=y
CONFIG_VT_CONSOLE=y
CONFIG_FRAMEBUFFER_CONSOLE=y
CONFIG_FRAMEBUFFER_CONSOLE_DETECT_PRIMARY=y
```

2. Cmdline (device tree or unpack/repack boot): add `panic=0` and optionally
   `console=tty0`. Prefer a **vendor_sunfish / BoardConfig** override gated by
   a make var (e.g. `SUNFISH_KERNEL_PANIC_DEBUG=1`) so normal bacon stays clean.

3. Build `bootimage`, name artifact
   `boot-resukisu-susfs-DEBUG-YYYYMMDDTHHMMSSZ.img`.

4. Flash only to `boot_b`; keep penúltimo on `boot_a`. On hang: photo if text
   appears; Vol−+Power → `--set-active=a`.

## Capture order (always)

1. Panic / hang on SusFS (debug) slot  
2. Fastboot **before** Android success on good slot  
3. Then penúltimo + immediate `dd` of `klog`/`logfs` (4a has no `fastboot fetch`)

## Status

Documented 2026-09-16 after SusFS early `kernel_panic` with empty Oops in klog.
Sigfix rebuild may already address root cause; keep this recipe for the next
opaque bootloop.