PS5_RetroArch/docs/RPCS3_PORT.md

RPCS3 as a libretro core: the port

This document is the audit behind porting RPCS3 (PlayStation 3) to the PS5 title as rpcs3_libretro.so, and the plan it leads to. Progress and run results are recorded in docs/ACTIVE.md and docs/PHASE_LOG.md, not here.

The objective

On my console, rpcs3_libretro.so boots God of War HD (the PSN release NPUA80490) through RetroArch's Load Content or /app0/args.txt. The game reaches gameplay, rendered by RPCS3's Vulkan renderer on RADV at a 300% resolution scale (3840×2160 internal for its 720p output). The evidence is:

• a RetroArch screenshot of gameplay whose picture I accept;
• ten minutes of play with no crash;
• the Close Content + reload battery passing;
• each 10 s audio window's speed, recorded. Full speed is not part of the objective, but its measurement is.

What the console holds (read in place, never copied anywhere):

Item	Where on the console
PS3 firmware	/app0/system/RPCS3/PS3UPDAT.PUP (206 MB)
The game	/app0/content/PS3/God of War.pkg (6.3 GB), a PSN package
Its licence	/app0/content/PS3/UP9000-NPUA80490_00-GODOFWARHDUS0000.rap

Because the game is a package and not a disc folder, the first content path is "install the package and its RAP, then boot the installed game". The installed copy needs another 6.3 GB on the console's storage.

The fork and the pin

../PS5_RPCS3 is my fork of RPCS3/rpcs3 (github.com/mihawk-99/PS5_RPCS3, public), with an upstream remote. Its main starts at upstream 1707d7fc883e (2026-09-28, "remove unnecessary #ifdef"): the newest master commit whose CI passed all thirteen checks, including RPCS3's FreeBSD build. The PS5's system software is FreeBSD-based, so that is the configuration closest to this port. Every port change is a commit on the fork's main, and tools/build-rpcs3.sh pins the fork by revision. Submodules RPCS3 names by relative URL (../../llvm/llvm-project.git and the rest) resolve from the fork as from upstream. A submodule that needs changes gets its own fork, ../PS5_<Name>, referenced by relative URL, as PS5_Azahar does with PS5_Dynarmic.

Licence

RPCS3 states its licence as GPL-2.0-only (its README; LICENSE is the GPLv2). The rest of the title is GPL-3.0-or-later (RetroArch, this port, the payload SDK fork and its platform layer), and GPL-2.0-only code and GPL-3.0 code cannot be combined into one work and distributed. Whether the core and the title are one work is not settled by the core being a separate .so; these are the facts that bear on it (2026-09-29):

• rpcs3_libretro.so statically links tooling/native/core_cxx_runtime.cpp (this repository, GPL-3.0-or-later by the repository's licence) through PS5_CORE_LINK_INPUTS, beside LLVM (Apache-2.0 WITH LLVM-exception, whose exception addresses GPLv2 combinations), FFmpeg and GNU libiconv (LGPL-2.1-or-later).
• At load time the title's native loader binds the core's libc and file-system imports to the title's own wrappers and to the platform layer (tools/core-imports.py, build/core_imports.inc), and the core runs in the title's process, on the title's heap, through RetroArch's libretro and Vulkan context interfaces.

So it is not in a release. The ways out are a licence decision for the owner of the GPL-3.0 parts that touch the core (dual-licensing core_cxx_runtime.cpp and the platform layer's bound functions under a GPLv2-compatible licence, which is possible only for code whose authors agree), a change of interface, or counsel's view that the combination is not one work; the licence audit of 2026-09-29 sets them out for that decision.

The title bundles no PS3 firmware, keys or games; RPCS3 installs the firmware the user supplies and decrypts packages with the user's own licence files (RAP); that audit covers those paths too.

Phase 1: the audit

1. Dependencies

RPCS3 builds its emulator as the static library rpcs3_emu, and its Qt application links that. Upstream already builds rpcs3_emu without Qt for its Android port (ANDROID in CMakeLists.txt): Qt, the Qt UI and the OpenGL renderer are left out, OpenAL is compiled out (WITHOUT_OPENAL) and the bundled FFmpeg is not used. The libretro build follows that path, with a LIBRETRO switch of its own where Android's choices differ.

3rdparty/ at the pin (submodule revisions in brackets):

Item	What RPCS3 uses it for	Decision
llvm (llvm-project ca7933e4, LLVM 22.1)	PPU and SPU recompilers	Build: a pinned static LLVM for x86_64-sie-ps5, X86 target only (below)
asmjit (416f7356)	SPU ASMJIT recompiler, trampolines, JIT helpers	Build, its code memory through the platform layer (gap a)
ffmpeg (RPCS3/ffmpeg-core 649d9d93, prebuilt)	video and audio decoding (cellVdec, cellAdec, ATRAC3+, cellMusic)	Build from source: a pinned FFmpeg release, static, software decoders (below); the prebuilt archive has no PS5 build
glslang (f0bd0257)	GLSL to SPIR-V for the Vulkan renderer's shaders	Build
GPUOpen/VulkanMemoryAllocator (1d8f600f)	Vulkan memory	Build (header library)
zlib (da607da7), zstd (f8745da6)	archives, save states, caches	Build
libpng (3061454d), stblib (013ac3be), bcdec	images, texture decoding	Build (bcdec and stb are headers)
yaml-cpp (51a5d623), pugixml (c8033ce9)	configuration, patches, XML	Build
SoundTouch (a0fba77b)	audio time-stretch in the resampler	Build
fusion (93254240)	motion-sensor fusion in PadHandler.cpp	Build (small C library)
unordered_dense	hash maps	Build (header)
protobuf (edaa823d)	RPCN (NP) messages	Stub: RPCN is compiled into rpcs3_emu unconditionally, so a LIBRETRO option leaves the NP network clients out with an offline implementation. Networking is dropped
wolfssl (3c5eead4), curl (01346829)	RPCN and clans over TLS	Drop, with the network clients (above)
miniupnp (d66872e3)	UPnP port mapping	Drop, with upnp_handler stubbed
libusb (87a55632)	USB passthrough (sys_usbd, usb_device)	Stub: no PS5 backend; sys_usbd reports no devices
hidapi	HID pads, only in rpcs3/Input	Drop (the libretro pad handler replaces rpcs3/Input)
rtmidi (1e5b4992)	MIDI instruments (Rock Band)	Build with RtMidi's dummy API, or stub the MIDI devices
OpenAL	microphone capture in cellMic	Drop: WITHOUT_OPENAL, as on Android
cubeb, FAudio, XAudio2	audio output backends	Drop: a libretro audio backend replaces them
libsdl-org/SDL	input, camera, FAudio's dependency	Drop
opencv	PS Move tracking in rpcs3/Input	Drop
discord-rpc, feralinteractive (GameMode), pine	Discord, GameMode, PINE IPC	Drop
7zip	not used by rpcs3_emu at the pin	Drop
MoltenVK, GL	macOS Vulkan, OpenGL headers	Drop (no OpenGL renderer, as on Android)
Qt 6	the UI	Drop

CMake options (top-level CMakeLists.txt):

Option	Default	Port
USE_NATIVE_INSTRUCTIONS	ON	OFF; -march=znver2 instead, the PS5's Zen 2 (AVX2, FMA, BMI2), set in the toolchain file
WITH_LLVM	ON	ON
BUILD_LLVM	OFF	OFF: LLVM is built separately and found through LLVM_DIR
STATIC_LINK_LLVM	OFF	ON
USE_FAUDIO, USE_SDL, USE_LIBEVDEV, USE_DISCORD_RPC, USE_GAMEMODE	ON/OFF	OFF
USE_VULKAN	ON	ON
USE_PRECOMPILED_HEADERS	OFF	OFF (ccache)
USE_SYSTEM_*	mixed	OFF throughout: every library is built for the PS5 or dropped
HAS_MEMORY_BREAKPOINTS, BUILD_RPCS3_TESTS, RUN_RPCS3_TESTS	OFF	OFF
USE_LTO	ON	OFF: a 1 GiB-class shared object links in time without it; revisit when it runs

LLVM. RPCS3 requires LLVM 18 or newer and builds 22.1 from its submodule. I build that same revision (ca7933e4) once, as a pinned static install (tools/build-llvm.sh into .deps/native/llvm-ps5), with prospero-clang, ccache, LLVM_TARGETS_TO_BUILD=X86, and no tools, tests, docs or examples, and point RPCS3 at it with LLVM_DIR. Keeping it out of RPCS3's build tree means a change to RPCS3 never rebuilds LLVM. LLVM's own Support layer assumes Unix facilities (mmap, sysconf, dladdr, signals) that the platform layer and the core loader's import table provide or refuse; the link shows which. The archive size, and what it adds to the core, are measured at step 3; LLVM with only the X86 target is on the order of a few hundred MB of archives, of which the core links the code generator, MCJIT and RuntimeDyld.

FFmpeg. RPCS3's prebuilt ffmpeg-core has no build for this console, so I build FFmpeg from a pinned source release: static, no programs, no network, no hardware acceleration. The decoders are the ones the PS3's media libraries need (H.264, MPEG-2, MPEG-4 Part 2, ATRAC3, ATRAC3+, AAC, MP3, AC-3, LPCM), with libavformat's MP4, MPEG-PS and raw demuxers, libswscale and libswresample. No encoders: video recording is dropped. Software decoding comes first. The console's hardware video decoder, which ProsperoLight uses, is a later option for H.264.

2. The frontend

RPCS3 drives Emu (the Emulator in rpcs3/Emu/System.h) from a frontend that fills g_emu_callbacks (rpcs3/Emu/emu_callbacks.h: 49 std::function hooks) and calls Emu.Init(). headless_application shows the minimum: it is a QCoreApplication whose callbacks create null renderers and handlers, and it refuses Vulkan. The libretro layer, rpcs3/libretro/ in the fork, replaces it without Qt:

• Entry points. retro_init sets RPCS3's directories (below) and fills the callbacks. retro_load_game installs the firmware if it is missing, installs a package if the content is one, then boots. retro_run runs the queued main-thread calls (call_from_main_thread, which RPCS3 uses for UI-side work on the frontend's thread), presents the newest frame and pushes audio. retro_unload_game stops Emu and waits for its threads.
• Vulkan. RPCS3 creates its own instance (API 1.2) and device (vkutils/instance.cpp, vkutils/device.cpp). Through RetroArch's context-negotiation interface (v2) the core creates the instance at the version RPCS3 asks for (create_instance), and the device with RPCS3's feature and extension choices (create_device2). RetroArch uses that instance and device. RetroArch's own instance is 1.1, which is why the core creates it. RPCS3's existing native_swapchain_base owns its presentable images. A swapchain_libretro on top of it presents by handing the finished image to RetroArch with set_image and set_signal_semaphore, in the layout RetroArch expects. Every vkQueueSubmit and present that RPCS3's RSX thread makes on the queue it shares with RetroArch goes between the interface's lock_queue and unlock_queue.
• Audio. A LibretroBackend : AudioBackend takes cellAudio's output through the backend's write callback, resamples it to RetroArch's rate (48 kHz; RPCS3's audio is 48 kHz already, so resampling is a copy until a game asks otherwise), converts it to 16-bit stereo and queues it. retro_run hands it over with the batch callback.
• Input. A libretro pad handler (a PadHandlerBase) maps the RetroPad to a DualShock 3: buttons, both sticks and the analogue triggers. Pressure sensitivity comes from the digital state. Keyboard, mouse, camera and music handlers are the null ones.
• Firmware. The Qt application installs PS3UPDAT.PUP in main_window::HandlePupInstallation (about 320 lines). The libretro layer does the same work without Qt: pup_object (Loader/PUP), the update packages' TAR extraction and the SPRX decryption. It runs on first boot when utils::get_firmware_version() is empty and reports progress through the RetroArch message interface.
• Content. The formats, in order:
  1. A PSN package plus its RAP. This is the game at hand. The layer installs it with package_reader (Crypto/unpkg), as main_window::HandlePackageInstallation does (about 380 lines), and copies the RAP to dev_hdd0/home/<user>/exdata/ (main_window::InstallFileInExData), then boots the installed dev_hdd0/game/<title>/USRDIR/EBOOT.BIN. An already installed package is not installed again.
  2. A disc game's folder (PS3_GAME/USRDIR/EBOOT.BIN).
  3. An ISO, which the pinned revision supports (Loader/ISO.cpp).
• Where RPCS3 keeps its files. RPCS3's emulator directory (dev_flash, dev_hdd0, config, caches) is /app0/system/RPCS3/, next to the firmware. Folders are 0777 and files at least 0666, so everything stays reachable over FTP.
• Core options and PS5 defaults. Resolution scale 300%. Shader mode asynchronous with the shader interpreter (async_with_interpreter, already upstream's default), so no game waits for a shader compile or relies on a warm cache. PPU and SPU decoders LLVM (upstream's defaults). Options are the libretro v2 kind, written to RPCS3's configuration when content loads (Phase 2 below).
• Core info. libretro-core-info has no RPCS3 file, so tooling/rpcs3/rpcs3_libretro.info is in this repository (name, extensions pkg|iso|bin|elf|self|sfo, firmware entry, GPLv2, needs_fullpath).
• Reference ports. Dolphin's Source/Core/DolphinLibretro/ (the Vulkan negotiation, its instance and device hooks and main-thread handling), PPSSPP's libretro port and Azahar's.

3. Platform gaps

Each gap is either already measured on the console (docs/PROBE.md, the platform layer's probes) or gets a probe step in the platform layer (src/probe.c, host tests in tests/test_platform.c), run inside the title with /app0/platform-probe.txt.

(a) Code memory for LLVM and asmjit. RPCS3 reserves code areas with utils::memory_reserve(size, can_be_jit=true) and commits them read-write-execute (protection::wx). Measured: direct memory mapped read-write and then given execute runs, read-write-execute included, and a protection change costs about 26 µs. ps5_exec_allocate has had no limit on live blocks since SDK d3e8625: 2,000 4 KiB blocks and 300 64 KiB regions ran on the console. LLVM uses the Small code model with PIC, so its code reaches RPCS3's helpers through RuntimeDyld stubs and needs no placement near the core. asmjit commits its 2 GiB area up front only under CAN_OVERCOMMIT (Linux), which the PS5 branch leaves undefined, so it grows on demand. To measure: a probe step that reserves a 2 GiB range, commits 64 KiB pieces read-write-execute on demand, and runs code in each, with the time a commit takes.

(b) Address-space reservations. RPCS3 reserves its guest memory in 4 GiB steps from 0x3_0000_0000 upward (Emu/Memory/vm.cpp):

Area	Size
g_base_addr + g_sudo_addr	8 GiB
g_exec_addr	12 GiB
g_hook_addr	32 GiB
g_stat_addr	4 GiB (g_free_addr, for SPU, starts right after it)

That is 56 GiB, plus JIT areas (2 GiB for asmjit, 768 MiB for each LLVM memory manager) and RSX's mappings. Measured (docs/PROBE.md): the GPU window is 0x2_0000_0000–0x2_FFFF_FFFF; from 0x4_0000_0000 at most 15 GiB; from 0x10_0000_0000 to 0x80_0000_0000 16 GiB is reserved at the hint itself; nothing is granted at or above 1 TiB; and a hint whose free space is too small is refused, not moved. The PS5 branch of memory_reserve therefore starts at 0x10_0000_0000, through ps5_vrange_reserve, which never draws on the title's 448 MiB flexible pool, where an anonymous mmap reservation would. To measure: one probe step reserving RPCS3's layout, 56 GiB in the sizes above from 0x10_0000_0000, to confirm 16 GiB is not a per-reservation cap for 32 GiB.

(c) Guest memory as views. RPCS3's utils::shm creates a memory object (memfd_create, or shm_open(SHM_ANON) on FreeBSD) and maps it at several addresses: g_base_addr and g_sudo_addr see the same memory at different protections. The PS5 branch uses ps5platform/shm.h: ps5_shm_create (one direct-memory object), ps5_shm_map at fixed addresses inside a ps5_vrange_reserve range, and ps5_memfd_create where RPCS3 wants a descriptor. The platform tests already cover several views of one object. To measure: 4 GiB of direct memory as two views, written through one and read through the other, and the time a 64 KiB view takes to map.

(d) 16 KiB host pages. RPCS3 already handles hosts whose pages exceed 4 KiB (Apple Silicon): vm.cpp stops protecting 4 KiB guest blocks one by one when utils::get_page_size() > 4096 and maps them read-write, and every mprotect is rounded to the host page. The RSX texture cache still protects pages to catch CPU writes, now 16 KiB at a time, so a write near a cached texture invalidates a wider range. To measure: what sysconf(_SC_PAGESIZE) returns in the title (it must be 16384; the platform layer answers it otherwise), and the texture cache's protection changes per frame in the game, from RPCS3's own counters, at 26 µs each.

(e) thread_local on emulated TLS. The core loader has no PT_TLS support, so a core's thread_local goes through __emutls_get_address. RPCS3 has 93 thread_local uses. The hot ones are cpu_thread::g_tls_this_thread, vm::g_tls_locked and atomic.cpp's wait callbacks, all read on every guest reservation and wait. To measure: the cost of an emulated-TLS read on the console (a probe step timing __emutls_get_address over a million reads), then RPCS3's rate of those reads in the game. If it matters, the fork keeps those few variables in a per-thread structure the thread already carries.

(f) Atomic waits. On FreeBSD, RPCS3's atomic.cpp uses its USE_STD path (std::condition_variable), and Utilities/sync.h emulates futex() off Linux, so it needs only pthread mutexes and condition variables, which the console exports. _umtx_op is exported too, if a faster path is wanted later. Nothing to add.

(g) Faults and ucontext. RPCS3's access-violation handler (Utilities/Thread.cpp) reads uc_mcontext.mc_rip, mc_err and the general registers on FreeBSD. The SDK's sys/_ucontext.h corrects the console's machine-context layout, and the platform probe already backpatches 200 fault sites from a handler. RPCS3 also installs SIGSEGV, SIGBUS, SIGILL and SIGPIPE handlers process-wide. In the title those would sit beside the title's own crash reporter. To measure: a guest page fault handled and resumed inside the core, with the title's reporter still catching a genuine crash.

(h) Threads. RPCS3's named_thread calls pthread_create, which the title binds to its factory (src/core_threads_ps5.cpp, 2 MiB minimum stack). RPCS3 creates a PPU thread for each guest thread, six SPU threads, the RSX thread and a pool of LLVM compile workers sized from sysconf(_SC_NPROCESSORS_ONLN). Measured by the thread probe (SDK 9a57ba7): thirteen CPUs (0–12) are available to the title, and threads run at policy 1, priority 700, in a range of 256 to 767. A priority set on a running thread reads back. pthread_getaffinity_np with FreeBSD's cpuset_t returns ERANGE, and RPCS3's set_thread_affinity_mask uses exactly that form. The platform layer gets ps5_pthread_setaffinity_np and ps5_pthread_getaffinity_np (the exported scePthreadSetaffinity/scePthreadGetaffinity with a 64-bit mask, or the size the kernel accepts), bound through tools/core-imports.py. sysconf(_SC_NPROCESSORS_ONLN) must answer 13. To measure: the affinity calls round-tripping on the console, and what sysconf answers.

4. Risks

Risk	How it is measured
LLVM does not build for the PS5 target, or its Support layer needs what the console lacks	the LLVM build (step 1) and the core's link and import report (step 3)
The core is too large for the loader (1 GiB image cap)	check-core.py and the loader's mapped_bytes (step 4)
Guest reservations do not fit below 1 TiB with the GPU window avoided	the reservation probe (gap b), then Emu.Init on the console
Emulated TLS costs too much in the hottest paths	the TLS probe (gap e), then the sampler in the game
RetroArch's Vulkan interface cannot give RPCS3 the device it needs (1.2 core, extensions)	device creation through create_device2 (step 4), and RPCS3's own capability log
Queue sharing with RetroArch stalls the RSX thread	the sampler on the RSX thread; frame timing
Firmware install needs host facilities the title lacks	step 5's install run, file by file
Shader compiles cost speed	windows during the game's first minutes with an empty cache
The package install fills the console's storage	the install run's free-space check before it starts
16 KiB pages widen the texture cache's invalidations	RPCS3's texture-cache counters in the game
The CPU cannot hold full speed (not part of the objective)	the 10 s windows, reported as they are

5. The ladder

Each step ends with its evidence in docs/ACTIVE.md and a dated entry in docs/PHASE_LOG.md.

1. Fork and build scripts. The fork at the pin; tools/build-llvm.sh (the pinned static LLVM); tools/build-ffmpeg.sh (the pinned FFmpeg); tools/build-rpcs3.sh on tools/core-fork.sh; tooling/rpcs3/ps5-toolchain.cmake; rpcs3 in core_names. Evidence: LLVM and FFmpeg archives with their sizes, and rpcs3_emu compiling for the PS5 target.
2. Host build (optional). The same libretro core for the host, debugged in a desktop RetroArch if this host's Vulkan driver allows. Evidence: the host core reaching the firmware check.
3. Link and ABI. The PS5 core links and passes tools/check-core.py; missing libc and kernel functions go into the platform layer with aliases in tools/core-imports.py. Evidence: check-core.py PASS and the import list.
4. Load. The core loads on the console and retro_init returns; the probe steps for gaps (a)–(h) run inside the title. Evidence: the loader's ready line, the probe's checks.
5. Firmware, then a homebrew program. PS3UPDAT.PUP installs from /app0/system/RPCS3/, then a small PS3 homebrew or test program boots before any commercial game. Evidence: the firmware version RPCS3 reports, and the program's output.
6. The game. God of War HD installed from its package and RAP, booted at 100%, then at 300%: screenshots, the speed of each window, the Close Content + reload battery and a ten-minute run. Evidence: the screenshot I accept, the windows, the battery lines and the ten-minute trace.

Phase 2: what the port turned out to need

Where the build and the first code differ from the audit above.

Dependencies.

• LLVM is my fork ../PS5_LLVM (github.com/mihawk-99/PS5_LLVM), pinned in tools/build-llvm.sh. The PS4/PS5 ABI ignores alignas on an empty base class, and LLVM relies on it twice. SmallVector<T, 0>'s layout assertions failed at build time; the fork aligns SmallVector itself under __SCE__. TrailingObjects failed silently: its empty aligner base is what raises a class to its trailing objects' alignment, so on the PS5 a header of an int and some bools stayed 4-aligned and 12 bytes, and two trailing pointers were given 28 bytes while getTrailingObjects read them from 16 to 32. The next allocation's first field overwrote the last pointer's upper half (MachineInstr::ExtraInfo's memory operands: God of War HD's SPU compiles crashed in MachineInstr::hasOrderedMemoryRef on 0x2_xxxx_xxxx, heap pointers with their upper 32 bits replaced by the count 2). The fork gives the aligner a zero-length member there, a non-empty base without storage; the PS5 target then lays such a class out as the host does (8-aligned, 16 bytes, 32 allocated, trailing objects at 16). The other empty alignas classes in LLVM and RPCS3 are standalone objects, whose alignment the ABI keeps. The build uses host tablegen tools (LLVM_NATIVE_TOOL_DIR) and builds only the libraries (LLVM_INCLUDE_TOOLS=OFF), since no LLVM program links for the console.
• FFmpeg 8.1.1 comes from its signed release tarball (tools/build-ffmpeg.sh), with RPCS3's own component list and NASM for its x86 assembly.
• GNU libiconv 1.18, static, comes from its signed release tarball (tools/build-libiconv.sh). cellL10n converts the PS3's character sets with iconv, and the console's libc has none.
• OpenAL Soft is built rather than compiled out: cellMic includes its headers outside WITHOUT_OPENAL off Android. Every backend is off, so it opens no device. Its sources are C++20 modules; CMake's dependency scan runs through tooling/rpcs3/clang-scan-deps, which gives the scanner the SDK's target and headers.
• zlib is the frontend's pinned build. libpng's generated configuration does not see the submodule's headers.
• pkg-config answers nothing in the toolchain file (tooling/rpcs3/ps5-toolchain.cmake). The host's packages would add the host's /usr/include.
• The network clients (RPCN, clans, UPnP) still build, with wolfSSL and curl. They are not stubbed yet; the title has no network use for them.
• The target defines __FreeBSD__ as 9, so RPCS3's FreeBSD branches take their pre-13 paths (shm_open(SHM_ANON) for memfd_create). The PS5 branch below replaces them where memory is concerned.

Vulkan (rpcs3/Emu/RSX/VK/vkutils/swapchain_libretro.* in the fork). RetroArch creates the instance with the core version RPCS3 asks for (1.2), and the device through create_device2. The core runs RPCS3's own render_device::create there, so the device has RPCS3's features and extensions plus RetroArch's; when the renderer starts, render_device::create runs again and adopts that device instead of creating one. Features RPCS3 enables only for some settings are the same whatever the game's configuration, so the device a boot needs is the one RetroArch made. Every submission and device-wide wait takes RetroArch's queue lock inside RPCS3's own submit lock. The swapchain is the core's own images, sampled by RetroArch:

• acquiring an image signals RPCS3's semaphore with an empty submission;
• presenting waits on RPCS3's semaphore and signals a fence;
• retro_run hands RetroArch the newest finished image with set_image, after its fence;
• an image RetroArch showed is reused only after RetroArch's frame index that last read it comes around again, which is when RetroArch has waited for that frame.

The images are not RPCS3's allocations, so they outlive the renderer while RetroArch may still show one; they go when a newer frame replaces them or the context is destroyed. The game boots in the first retro_run after RetroArch's context is up, because RPCS3 builds its renderer while booting.

Input (rpcs3/libretro/libretro_pad_handler.*). RetroPads 1 to 4 are the PS3's controllers, through a pad handler on RPCS3's generic machinery (SDL's value conventions). The core compiles rpcs3/Input/pad_thread.cpp and what it needs, without the HID handlers (no hidapi on the console), and writes the input configuration that names the RetroPads before the pad thread loads it.

Memory (the __PROSPERO__ branch of rpcs3/util/vm_native.cpp). RPCS3's reservations, commits and shared memory go through the platform layer:

• reservations are ps5_vrange_reserve and ps5_vrange_reserve_at;
• commits and decommits are ps5_vrange_commit and ps5_vrange_decommit, direct memory in 64 KiB units (SDK 7f3d3ff);
• utils::shm is a ps5_shm direct-memory object with its views.

Guest memory starts at 64 GiB (0x10_0000_0000). The 32 GiB hook area is only reserved: nothing reads it, and a 32 GiB copy-on-write view of zeros has no direct-memory form. The page size is the kernel's 16 KiB. The core's reservations are released, with the memory committed in them, when the core is unloaded, so the next load finds its addresses free.

Faults. In the libretro core, a fault RPCS3 does not handle goes back to the handler it replaced (the title's crash reporter), and the title's handlers return when the core is unloaded.

Platform gaps closed in the SDK (8160289). Each is aliased in tools/core-imports.py.

• No export at all: accept4, getpagesizes, in6addr_any.
• Exported, but resolved to nothing in a title: gai_strerror, statfs, fstatfs, umask, fork, setsid, wait4.
• Formerly taken from the SDK's static payload libc, whose system calls a title may not make: syscall (only SYS_write), getpwnam_r, posix_madvise, strsignal.
• Answered differently on the console: pthread_getaffinity_np and pthread_setaffinity_np (the 64-bit mask), sysconf (13 CPUs, not 16), pthread_exit (a thread's thread_local destructors first).
• Refused: realpath answers EPERM, even for /app0, so libc++'s std::filesystem::canonical and weakly_canonical came back empty and the package installer could not normalise its path. ps5_realpath makes the path absolute, resolves . and .. by name and checks each component with stat; it keeps a symbolic link's name. The title links it too (--wrap=realpath).
• Memory: committed ranges (ps5_vrange_commit), exact reservations, zeroing of reused direct memory, and placement up to 1 TiB.

The title's core loader answers a core's dlopen(NULL) with the process handle (src/core_loader_ps5.cpp), which LLVM's JIT needs.

What the console run needed in the fork is recorded in docs/PHASE_LOG.md (2026-09-28): RSX's start order, VMA's entry points under volk, the kqueue trigger RSX audio's timer uses, releasing LLVM's memory-manager ranges, the log listeners' lifetime, and quitting through Emulator::Quit.

Content loading and the loading screen (rpcs3/libretro/libretro_loader.* in the fork). retro_load_game returns at once: the firmware and a PSN package install on a worker thread while retro_run shows a loading screen, and the game boots when they are done. The screen is drawn on the CPU (the stb libraries RPCS3 already has) and handed to RetroArch as a Vulkan image, one per RetroArch frame index, with the copy submitted through set_command_buffers:

• a violet night behind the game's own art (its PIC1, blurred and tinted), its ICON0 on a glass card, the title in Inter, and a violet-to-orchid bar with a sweeping highlight;
• "Installing firmware" with its packages, "Installing" with the bytes, the speed, the time left and the percentage, then "Starting" with RPCS3's compile progress, until RPCS3's first frame replaces it;
• what failed, in rose, when something does.

Inter 4.1 (SIL Open Font License, its licence beside it) is fetched by tools/build-rpcs3.sh, pinned by digest, and staged in system/RPCS3/fonts; the firmware's Rodin is the fallback. A finished package install is recorded in system/RPCS3/libretro/installed/<title ID>, since an interrupted one leaves an EBOOT.BIN behind, and the record goes when an install starts. Closing content during an install stops it, inside a large file too (the fork's unpkg.cpp); a partial firmware is installed again next time.

RPCS3's folder, as staged. Besides the loading screen's fonts, the title stages RPCS3's own overlay images (bin/Icons/ui into system/RPCS3/Icons/ui), which its native dialogs draw. The configuration the core writes at load also turns RPCS3's GDB server off: no debugger connects to a core, and it would only open a socket on the console. Open question: the server's address did not match RPCS3's IPv4 std::regex on the console (it fell through to the Unix socket branch), which may mean std::regex misbehaves there; RPCS3 also parses patches and its game database with it, so it wants a probe.

What loads. A PSN package (.pkg, installed once, then booted at once), a game's EBOOT.BIN, an ISO, or a folder (RetroArch's "Use this directory"): the folder's USRDIR/EBOOT.BIN (an installed game, such as system/RPCS3/dev_hdd0/game/NPUA80490) or PS3_GAME/USRDIR/EBOOT.BIN (a disc game) boots. RPCS3 itself treats a bare folder as "build the PPU cache of everything in it", which compiled and stopped. Loading a folder also first crashed the title: canonicalising a relative path asks libc++ for the working directory, and the title's own getcwd resolves to nothing on the console (libc's calls __getcwd, which only libkernel_sys has). The title links it to the platform's ps5_getcwd (--wrap=getcwd), as the cores already were, and tooling/native/app-symbols.map keeps every __wrap_ symbol local, since lld exported __wrap_getcwd to interpose on libc's stubs and a title publishes no exports.

Core options (rpcs3/libretro/libretro_options.* in the fork). Every RPCS3 setting with a set of values is a libretro v2 core option, one category per section of RPCS3's configuration: CPU (Core), Virtual File System, GPU (Video, with its Vulkan, performance overlay and shader loading dialog subsections), Audio, Input, System, Network, Save States and Miscellaneous. They are built from the configuration tree itself, so their names, values (an enum's names; a number's range as a list: all of a small range, else the 1-2-5 series, even steps, the bounds and the default), defaults and whether RPCS3 takes a change while a game runs are RPCS3's own. A change RPCS3 takes live applies at once; the rest are written to config.yml when content loads, as RPCS3's settings dialog writes them, so a game's custom configuration still overrides them. Left out: what the core fixes itself (the Vulkan renderer, RetroArch's audio backend, the RetroPads in place of keyboards, mice, cameras and Move), the Qt application's window behaviour (auto-start and auto-exit, fullscreen, focus pause, native UI, GameMode), settings for other hosts (Metal), VSync (RetroArch paces frames) and RPCS3's savestate folder limits. Paths and free-text settings have no set of values to offer. The resolution scale keeps 100% to 300% (the frame is 720p at the scale, 2160p at most), 300% by default.

Game patches (rpcs3/libretro/libretro_patches.*). RPCS3 has no frame-rate unlock of its own: a game runs faster than it was made to only through the patches in RPCS3's game patch database. The fork keeps that database as RPCS3's patch manager downloads it (bin/patches/patch.yml, its source, date and hash in bin/patches/SOURCE; 815 executables, 502 of them with a frame-rate patch on 2026-09-29), and the title stages it where RPCS3 reads it (system/RPCS3/patches/). The "Frame-rate patches" core option, on by default, turns each game's frame-rate patch on when content loads: "60 FPS" where the database has one, else "Unlock FPS", which RPCS3's frame limit holds at the display's rate; one per executable, serial and version, and another rate (30, 50, 120), a fallback variant or a "No User Input" one stays off. RPCS3's patch_config.yml is written only when that changes, and keeps the state of every other patch. A patch for a game the database lacks goes in patches/<serial>_patch.yml, which RPCS3 reads for that game.

Save states (rpcs3/libretro/libretro_state.*). RetroArch's save states are RPCS3 savestates. RPCS3 writes one to a file system in memory, a virtual device like its ISO one (Emulator::savestate_path_override points the savestate there), and the game boots again from it, as RPCS3's own "save state and continue" does; loading a state stops the game and boots the state in its place. Nothing goes through the console's storage but RetroArch's own state file. RetroArch asks for a state's size right before it serializes one, and before it loads one (to back up what runs for "Undo Load State"), so the core makes the state at the size query and keeps it until the next frame: one request costs one savestate. RPCS3 refuses a savestate while an SPU cannot be stopped (its "Compatible Savestate Mode" option), a video decoder context exists (LLE libvdec avoids it) or the game is saving; the game then runs on and RetroArch reports the failure. The core declares its states variable in size and platform-dependent, and its .info offers basic save states only (no rewind or run-ahead, which RPCS3 savestates cannot serve). The pad script's SAVE_STATE and LOAD_STATE actions save and load the current slot, so a test run can start from a known scene (and SCREENSHOT keeps the frame shown then as /app0/pad-shot-<n>.png, so one run shows each screen it walks through); RetroArch names the state after the content, so a game loaded as its folder (dev_hdd0/game/GTA4) has GTA4.state, where an EBOOT.BIN gives every game EBOOT.state.

A title's write budget. A title writes at full speed for a burst of a few GiB and then at about 2 MiB/s, buffered or direct, while another process writes the same folder faster (the SDK's docs/PROBE.md, "Sustained writes"). God of War HD's 6.3 GB package took 31.5 minutes to install. Installing a package's large files without copying them, read and decrypted from the package the way RPCS3 reads an ISO through a virtual device, would remove the wait and the second copy.