jpolo1224
b762cc01de
Two reports from Rei Ayanami, one of which turned out to be a real gap rather
than a misunderstanding.
A game could report "3 game patches are active" with an empty patch list and
nothing anywhere to turn them off. Those patches come from the ~2 MB patches.zip
we ship, and the manager only ever listed files in the patches folder, so
everything inside the zip applied invisibly. Worse, the core auto-applies any
group with no [Name] ("we auto enable anything that's not labelled" --
Patch.cpp), and a group with no name has nothing for a toggle to hang off.
There is now a card showing exactly what the bundled zip contributes to this
game, with unlabelled groups marked as always-on, and a button to copy the file
into the patches folder. That is not convenience: the core prefers a pnach on
disk over the zip and explicitly disables the bundled copy when it finds an
unlabelled patch on disk, so extracting both makes the cheats individually
switchable AND takes the invisible copy out of play. It is the only way to turn
an unlabelled bundled patch off at all. The card is hidden when the game already
has a pnach on disk, because then the zip contributes nothing and showing it
would be a lie.
All on / All off sits above the cheat list, not below: a community pnach can run
to a hundred entries, and a control you have to scroll past all of them to reach
does not solve the problem it exists for. It rewrites the file once rather than
once per cheat -- a hundred read-modify-writes is a hundred chances to
half-apply -- and each button disables itself when there is nothing left to do.
ARMSX2 — Native ARM64 JIT Fork of PCSX2
ARMSX2 is a free and open-source PlayStation 2 (PS2) emulator based on PCSX2. Its purpose is to emulate the PS2's hardware, using a combination of MIPS CPU Interpreters, Recompilers and a Virtual Machine which manages hardware states and PS2 system memory. This allows you to play PS2 games on your phone, PC, or gaming handheld, with many additional features and benefits.
Thank You
The ARMSX2 team is eternally indebted to the PCSX2 project it is based on. We are so fortunate to build on their 20 years of hardcore development.
About This Fork
The upstream PCSX2 project ships an ARM64 interpreter build for ARM, but its high-performance JIT recompilers (EE, IOP, VU0, VU1, and vtlb fast memory) are x86-64 only.
This fork exists to close that gap. The goal is to preserve the correctness features of 20 years of PCSX2 development, while generating the fastest native ARM performance possible.
Current status:
- ✅ EE (Emotion Engine) recompiler — integer, float, MMI, COP0/COP1/COP2, branches, load/store
- ✅ IOP (I/O Processor / R3000A) recompiler — full integer, load/store, branches, coprocessors
- ✅ VU (Vector Unit) recompiler — microVU skeleton + Upper FMAC vector ISA complete; Lower ISA and runtime complete
- ✅ vtlb fast memory
- ✅ Native ARM64 binary builds and boots the PS2 BIOS
- ✅ 2D games are already playable
- ✅ 3D games run
Why LLMs / AI Were Used
A word on methodology:
The x86-64 JIT code in upstream ARMSX2 is already proven correct — it has run thousands of PS2 titles for years. The challenge in this port is not emulator design or JIT theory; it is mechanical translation of a large, well-understood x86-64 assembly codebase into equivalent ARM64 assembly (via VIXL) while preserving the exact same register-allocation contracts, block lifecycle, and recompiler semantics.
Large language models (LLMs) were used as an accelerant for this translation work — pattern-matching x86 JIT boilerplate to ARM64 equivalents, scaffolding emit routines, and keeping the porting velocity high. The JIT logic (block compiler, dispatcher, analysis passes, flag pipelines, clamping rules, Tri-Ace hacks, etc.) is taken directly from the upstream x86 implementation and validated against it. Nothing was hallucinated from scratch.
In other words: the hard engineering was done by the PCSX2 team over two decades. The hard typing — translating ~50k lines of x86 emitter code into ARM64 — is what AI helped compress.
System Requirements
ARMSX2 targets ARM64 across desktop (macOS, Windows, Linux) and mobile (Android, iOS/iPadOS), all from the single shared core. Our setup documentation page contains additional details on software and hardware requirements.
Please note that a BIOS dump from a legitimately-owned PS2 console is required to use the emulator. For more information, visit this page.
Building
Check out our github actions for the latest build recipe