# Building psx-beetle on Linux

The psx-beetle oracle builds and runs on Linux with the same wire protocol
as on Windows. Verified 2026-07-02 (Kula World boots to demo gameplay;
ping/screenshot served over the TCP debug protocol).

## beetle-psx checkout

`runtime/src/beetle_libretro.cpp` targets the C++ beetle-psx tree. Upstream
master has since been converted to plain C (`libretro.cpp` -> `libretro.c`,
`PS_CPU` class dropped), which no longer compiles against our integration.
Pin the checkout to the last compatible commit — the same base
`docs/beetle_wtrace_hook.patch` was generated from:

```bash
git clone https://github.com/libretro/beetle-psx-libretro.git beetle-psx
cd beetle-psx
git checkout 5759277b          # "audit pass" — last C++-tree base we target
for p in wtrace_hook sio_trace_hook cdcmd_trace_hook rtrace_irq_hook \
         guest_cycles_hook cdc_dma_peek_hook spu_event_hook; do
    git apply ../docs/beetle_$p.patch    # in this order; each builds on the last
done
```

Every hook `beetle_libretro.cpp` and `beetle_debug_server.c` link against is
now in `docs/beetle_*.patch` (added 2026-09-29): the rtrace/IRQ callbacks, the
guest-cycle clock and the per-instruction PC hook behind `cyc_watch`, the
CDC/DMA IRQ peeks, `PS_CDC::PSXRecomp_GetDecodeVolume` and the SPU event
calls. `beetle_cdcmd_trace_hook.patch` is now a diff on top of the wtrace and
SIO patches, so there is no duplicate block to remove. `beetle-macos.md` has a
table of what each patch adds. The set was verified from a fresh clone on
macOS; this Linux recipe has not been re-run with it.

`beetle_cdcmd_trace_hook.patch` adds a CD-command trace callback (fires per
command dispatch in cdc.cpp) exposed as the `cdrom_cmd_dump` / `cdrom_cmd_reset`
debug commands — used to oracle-diff the Kula World CD read sequence.

`beetle_sio_trace_hook.patch` adds `FrontIO::SetSIOTraceCallback` (fires per
completed SIO byte exchange) — an integration hook beetle_libretro.cpp needs
that predated the committed wtrace patch.

## Build

```bash
# Static lib. On unix the artifact is named mednafen_psx_libretro.so but is
# an ar archive (STATIC_LINKING=1); stage it under the name cmake expects.
make platform=unix STATIC_LINKING=1 HAVE_LIGHTREC=0 -j"$(nproc)"
cp mednafen_psx_libretro.so libmednafen_psx.a

cd ../runtime
# Current master's runtime configure also needs the lib/recomp-net and
# lib/retcomm-rbengine submodules (git submodule update --init ..., or
# -DPSX_REWIND=OFF) and recompiled BIOS C. psx-beetle links no recompiled
# code, so -DPSXRECOMP_ALLOW_NO_BIOS=ON skips the BIOS check
# (beetle-macos.md, step 3).
cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DPSX_RECOMP_UI=OFF -DPSX_DEBUG_TOOLS=ON \
      -DPSXRECOMP_ALLOW_NO_BIOS=ON
ninja -C build psx-beetle

# Run (SDL window; use software renderer if GL context is flaky).
# Beetle looks for lowercase scph5501.bin in the BIOS directory (SHA1
# 0555C6FA… — SCPH-5501). Symlink or copy next to SCPH1001.BIN.
# psxrecomp's bios/openbios.bin works under that name too; see
# beetle-macos.md ("BIOS") for the silent fallback to Beetle's own OpenBIOS.
# Default debug port is 4382 (override with --port).
SDL_RENDER_DRIVER=software ./runtime/build/psx-beetle ../bios/SCPH1001.BIN --disc <game.cue> --port 4380

# Headless: SDL's dummy video driver needs no X server.
# SDL_VIDEODRIVER=dummy SDL_RENDER_DRIVER=software ./runtime/build/psx-beetle ...
# Or, if xvfb is installed:
# xvfb-run -a ./runtime/build/psx-beetle ../bios/SCPH1001.BIN --disc <game.cue>
```

Wire smoke: `{"cmd":"ping"}` → `backend=beetle`. Screenshot via `screenshot`.
`gpu_frame_dump` is a **native** (psx-runtime) command — Beetle does not
expose GP0 OT dumps yet; compare visuals via `screenshot` / `vram_peek`.