# DF-4826 — amdgpu_acp.c is a dead translation unit on DragonFly

## Claim
`sys/dev/drm/amd/amdgpu/amdgpu_acp.c` is never compiled into the DragonFly
kernel or the `amdgpu.ko` module, and cannot be compiled as-shipped. Every
code path in it — including the four open pass-1 findings **DF-1907, DF-1908,
DF-1909, DF-1910** — is unreachable at runtime on a DragonFly system.

## Build
Nothing to build (that is the finding):

    sh build.sh            # include-resolution gate; any C compiler dies on
                           # <linux/pm_domain.h>, which does not exist in
                           # sys/dev/drm/include/

## Run

    sh run.sh              # deterministic tree checks + recorded guest artifact check

## Expected output (all five verdict inputs)
1. `amdgpu_acp.c` appears in **no** SRCS line of
   `sys/dev/drm/amd/amdgpu/Makefile` (the only "acp" hit is `amdgpu_acpi.c`,
   a different file — line 168).
2. `sys/dev/drm/include/linux/pm_domain.h` **does not exist** (only
   `pm.h`, `pm_qos.h`, `pm_runtime.h`); the entire
   `sys/dev/drm/include/sound/` directory **does not exist**, so
   `<sound/designware_i2s.h>` and `<sound/pcm.h>` (amdgpu_acp.c:29-30) are
   fatal include errors.
3. `CONFIG_DRM_AMD_ACP` is **never defined** anywhere in `sys/` — its only
   occurrences are `#ifdef`/`#if defined` consumers
   (amdgpu.h:823, vi.c:74/1685/1706, smu8_hwmgr.c:667), so `adev->acp`,
   the `acp_ip_block` registration in vi.c, and the smu8 ACP hwmgr path are
   all compiled out.
4. No `mfd_add_hotplug_devices` / `mfd_add_devices` / `mfd_remove_devices` /
   `pm_genpd_init` / `pm_genpd_add_device` / `bus_find_device_by_name`
   implementation exists anywhere in `sys/` — the DFly mfd/genpd "shims" are
   include-guard-only headers (`mfd/core.h` defines nothing;
   `struct platform_device` is an empty struct).
5. Guest binary artifact: `/boot/kernel/amdgpu.ko` contains **zero** amdgpu
   ACP symbols (`acp_ip_block`, `acp_hw_init`, `acp_poweron`, …) while the
   acpi positive control matches 17.

## Files
- `check_dead.sh` — deterministic tree + membership checks (the PoC source)
- `build.sh` / `run.sh` — exact commands
- `run.log` — full untrimmed output of the decisive run (host + guest)
- `env.txt` — host git rev, guest uname
- `VERDICT.md` — full narrative
- `manifest.json` / `verdict.json`

No `fix.diff`: this is a reachability refutation, not a memory-corruption
finding; there is no kernel defect introduced by this file on DragonFly
(because the file is not in the kernel). Recommended triage action lives in
`verdict.json` `recommended_fix`.