[scarletnx] Add CPU backend

Signed-off-by: lizzie <lizzie@eden-emu.dev>
Assisted-by: Claude Opus 5.5 <claude@anthropic.com>

CMakeLists.txt

@@ -304,6 +304,16 @@ if (ARCHITECTURE_arm64 AND (ANDROID OR LINUX))
     add_compile_definitions(HAS_NCE=1)
 endif()
 
+set(ENABLE_SCARLETNX_DEFAULT ON)
+if ((NOT LINUX AND NOT FREEBSD) OR (NOT CMAKE_C_COMPILER_ID MATCHES "Clang" OR NOT CMAKE_CXX_COMPILER_ID MATCHES "Clang"))
+    set(ENABLE_SCARLETNX_DEFAULT OFF)
+endif()
+option(ENABLE_SCARLETNX "Enable the ScarletNX recompiler CPU backend (requires Clang and LLVM)" "${ENABLE_SCARLETNX_DEFAULT}")
+if (ENABLE_SCARLETNX)
+    set(HAS_SCARLETNX 1)
+    add_compile_definitions(HAS_SCARLETNX=1)
+endif()
+
 if (YUZU_ROOM)
     add_compile_definitions(YUZU_ROOM)
 endif()

cpmfile.json

@@ -243,6 +243,27 @@
         "repo": "crosire/reshade",
         "version": "v6.8.0"
     },
+    "scarletnx": {
+        "bundled": true,
+        "hash": "93f7e6810644253d6396239092d5769c44b005fa7a17cf39c6d773050a19de74fca1f96bb6eec7cb40384eb158b2595c9e1171ad592d8eb8326fd31f5632f505",
+        "options": [
+            "SNX_BUILD_NX OFF",
+            "SNX_BUILD_GNUABI OFF",
+            "SNX_BUILD_3DS OFF",
+            "SNX_BUILD_VITA OFF",
+            "SNX_BUILD_AGB OFF",
+            "SNX_DEPLOY OFF",
+            "SNX_BUILD_TESTING OFF",
+            "SNX_BUILD_GUI OFF",
+            "SNX_MULTICALL OFF",
+            "SNX_TRACY OFF",
+            "SNX_RECOMPILER_SHARED OFF",
+            "SNX_LLVM_SHARED OFF"
+        ],
+        "package": "ScarletNX",
+        "repo": "scarletnx/ScarletNX",
+        "version": "f16810ce9c"
+    },
     "sdl3": {
         "hash": "df5a323af7ac366661a3c0e887969c72584d232f3cc211419d59b0487b620b6b2859d4549c9e8df002ee489290062e466fcfddf7edc0872a37b1f2845e81c0f3",
         "min_version": "3.2.10",
@@ -351,13 +372,13 @@
     },
     "zstd": {
         "find_args": "MODULE",
-        "hash": "2b006c3c110c38bd2f5896b42d36a38931c8eae261f30552f9a9fd04458d218d8f1a1425f117fd12af545ed77042e4b2d1a1a9b6286c4d0b9d74ef79f20a8f08",
+        "hash": "cc5ad4b119a9c2ea57f0b71eeff01113bb506e0d17000159c5409cb8236d22e38c52d5e9e97e7947a4bf1b2dfc44b6c503ab2d9aedbd59458435c6a2849cb029",
         "min_version": "1.5",
         "options": [
             "ZSTD_BUILD_SHARED OFF"
         ],
         "repo": "facebook/zstd",
         "source_subdir": "build/cmake",
-        "version": "33618c8"
+        "version": "b8d6101fba"
     }
 }

docs/Options.md

@@ -78,6 +78,9 @@ The following options are desktop only.
 - `ENABLE_OPENGL` (ON) Enable the OpenGL graphics backend
   - Unavailable on Windows/ARM64 and on Android
   - You probably shouldn't turn this off.
+- `ENABLE_SCARLETNX` (OFF) Enable the ScarletNX recompiler
+  - Requires Clang and LLVM's development files
+  - Needs multicore and fastmem
 
 ### Qt
 

externals/CMakeLists.txt

@@ -249,6 +249,14 @@ if (YUZU_TESTS OR DYNARMIC_TESTS)
     AddJsonPackage(catch2)
 endif()
 
+# ScarletNX
+if (ENABLE_SCARLETNX)
+    AddJsonPackage(scarletnx)
+    if (TARGET scarletnx-recompiler)
+        set_target_properties(scarletnx-recompiler PROPERTIES SYSTEM ON)
+    endif()
+endif()
+
 # getopt
 if (MSVC)
     add_subdirectory(getopt)

src/android/app/src/main/java/org/yuzu/yuzu_emu/model/Game.kt

@@ -100,7 +100,7 @@ class Game(
 
     companion object {
         val extensions: Set<String> = HashSet(
-            listOf("xci", "nsp", "nca", "nro", "nsz", "xcz")
+            listOf("xci", "nsp", "nca", "nro")
         )
     }
 }

src/android/app/src/main/java/org/yuzu/yuzu_emu/utils/GameHelper.kt

@@ -109,7 +109,7 @@ object GameHelper {
 
     // File extensions considered as external content, buuut should
     // be done better imo.
-    private val externalContentExtensions = setOf("nsp", "xci", "nsz", "xcz")
+    private val externalContentExtensions = setOf("nsp", "xci")
 
     private fun scanContentContainersRecursive(
         files: Array<MinimalDocumentFile>,

src/android/app/src/main/jni/game_metadata.cpp

@@ -76,9 +76,7 @@ jboolean Java_org_yuzu_yuzu_1emu_utils_GameMetadata_getIsValid(JNIEnv* env, jobj
             auto const file_type = loader->GetFileType();
             if (file_type == Loader::FileType::Unknown || file_type == Loader::FileType::Error)
                 return false;
-            if ((file_type == Loader::FileType::NSP || file_type == Loader::FileType::XCI ||
-                 file_type == Loader::FileType::NSZ || file_type == Loader::FileType::XCZ) &&
-                !Loader::IsBootableGameContainer(file, file_type))
+            if ((file_type == Loader::FileType::NSP || file_type == Loader::FileType::XCI) && !Loader::IsBootableGameContainer(file, file_type))
                 return false;
             u64 program_id = 0;
             return loader->ReadProgramId(program_id) == Loader::ResultStatus::Success;

src/common/settings.h

@@ -256,7 +256,9 @@ struct Values {
                                                     CpuBackend::Dynarmic,
 #endif
                                                     CpuBackend::Dynarmic,
-#ifdef HAS_NCE
+#if defined(HAS_SCARLETNX)
+                                                    CpuBackend::ScarletNx,
+#elif defined(HAS_NCE)
                                                     CpuBackend::Nce,
 #else
                                                     CpuBackend::Dynarmic,

src/common/settings_enums.h

@@ -138,7 +138,7 @@ ENUM(RendererBackend, OpenGL_GLSL, Vulkan, Null, OpenGL_GLASM, OpenGL_SPIRV);
 ENUM(GpuAccuracy, Low, High);
 ENUM(DmaAccuracy, Default, Unsafe, Safe);
 ENUM(GpuFenceBehavior, Default, Immediate, Balanced, Accurate);
-ENUM(CpuBackend, Dynarmic, Nce);
+ENUM(CpuBackend, Dynarmic, Nce, ScarletNx);
 ENUM(CpuAccuracy, Auto, Accurate, Unsafe, Paranoid, Debugging);
 ENUM(CpuClock, Normal, Boost, Overclock)
 ENUM(MemoryLayout, Memory_4Gb, Memory_6Gb, Memory_8Gb, Memory_10Gb, Memory_12Gb);

src/common/zstd_compression.cpp

@@ -1,6 +1,3 @@
-// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
-// SPDX-License-Identifier: GPL-3.0-or-later
-
 // SPDX-FileCopyrightText: Copyright 2019 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -49,10 +46,4 @@ std::vector<u8> DecompressDataZSTD(std::span<const u8> compressed) {
     return decompressed;
 }
 
-std::size_t DecompressDataZSTD(std::span<const u8> compressed, std::span<u8> output) {
-    const std::size_t result =
-        ZSTD_decompress(output.data(), output.size(), compressed.data(), compressed.size());
-    return ZSTD_isError(result) ? 0 : result;
-}
-
 } // namespace Common::Compression

src/common/zstd_compression.h

@@ -1,6 +1,3 @@
-// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
-// SPDX-License-Identifier: GPL-3.0-or-later
-
 // SPDX-FileCopyrightText: Copyright 2019 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -45,15 +42,4 @@ namespace Common::Compression {
  */
 [[nodiscard]] std::vector<u8> DecompressDataZSTD(std::span<const u8> compressed);
 
-/**
- * Decompresses a single Zstandard frame into a caller-provided buffer of known size.
- *
- * @param compressed the compressed source memory region.
- * @param output     the destination buffer. Its size is the maximum number of bytes to write.
- *
- * @return the number of bytes written, or 0 if the frame is invalid or doesn't fit. An empty
- *         frame also returns 0.
- */
-[[nodiscard]] std::size_t DecompressDataZSTD(std::span<const u8> compressed, std::span<u8> output);
-
 } // namespace Common::Compression

src/core/CMakeLists.txt

@@ -33,8 +33,6 @@ add_library(core STATIC
     crypto/encryption_layer.h
     crypto/key_manager.cpp
     crypto/key_manager.h
-    crypto/ncz_decompressor.cpp
-    crypto/ncz_decompressor.h
     crypto/partition_data_manager.cpp
     crypto/partition_data_manager.h
     crypto/xts_encryption_layer.cpp
@@ -1250,6 +1248,18 @@ if (HAS_NCE)
     target_link_libraries(core PRIVATE merry::oaknut)
 endif()
 
+if (HAS_SCARLETNX)
+    target_sources(core PRIVATE
+        arm/scarletnx/arm_scarletnx_32.cpp
+        arm/scarletnx/arm_scarletnx_32.h
+        arm/scarletnx/arm_scarletnx_64.cpp
+        arm/scarletnx/arm_scarletnx_64.h
+        arm/scarletnx/scarletnx_api.h
+        arm/scarletnx/scarletnx_process.cpp
+        arm/scarletnx/scarletnx_process.h)
+    target_link_libraries(core PRIVATE ScarletNX::recompiler)
+endif()
+
 if (ARCHITECTURE_x86_64 OR ARCHITECTURE_arm64 OR ARCHITECTURE_riscv64 OR ARCHITECTURE_loongarch64)
     target_sources(core PRIVATE
         arm/dynarmic/arm_dynarmic.h

src/core/arm/scarletnx/arm_scarletnx_32.cpp

@@ -0,0 +1,227 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <cstring>
+#include <utility>
+#include <atomic>
+
+#include "common/logging.h"
+#include "core/arm/scarletnx/arm_scarletnx_32.h"
+#include "core/core.h"
+#include "core/core_timing.h"
+#include "core/hle/kernel/k_process.h"
+
+namespace Core {
+
+namespace {
+
+// The exit SignalInterrupt sets, which no block sets itself.
+constexpr u32 InterruptExit = 0x1000;
+constexpr u32 UserMode = 0x10;
+constexpr u32 ModeMask = 0x1F;
+
+// FPSCR splits into FPSR and FPCR as in ArmDynarmic32.
+std::pair<u32, u32> FpscrToFpsrFpcr(u32 fpscr) {
+    const u32 fpsr = (fpscr & 0xf8000000) | (fpscr & 0x80) | (fpscr & 0x1f);
+    const u32 fpcr = (fpscr & 0x7ff8000) | (fpscr & 0x1f00);
+    return {fpsr, fpcr};
+}
+
+u32 FpsrFpcrToFpscr(u64 fpsr, u64 fpcr) {
+    const auto [s, c] = FpscrToFpsrFpcr(u32(fpsr | fpcr));
+    return s | c;
+}
+
+} // namespace
+
+ArmScarletNx32::ArmScarletNx32(std::shared_ptr<ScarletNxProcess> process, std::size_t core_index)
+    : ArmInterface{true}, m_process{std::move(process)}, m_core_index{core_index} {
+    m_rt.coproc = &Coprocessor;
+    m_cpu.parent = this;
+    m_cpu.cpu.mem = m_process->m_arena;
+    m_cpu.cpu.mem_size = 1ULL << 32;
+    m_cpu.cpu.rt = &m_rt;
+
+    m_fault_scope.memory = &m_process->m_process.GetMemory();
+    m_fault_scope.arena = m_process->m_arena;
+    m_fault_scope.arena_size = ScarletNxProcess::ArenaSize;
+}
+
+ArmScarletNx32::~ArmScarletNx32() {
+    snx_recompiled32_free(m_module);
+}
+
+int ArmScarletNx32::Svc(void* context, u32 imm, u64 number, const u64 arguments[6]) {
+    auto& self = *static_cast<ArmScarletNx32*>(context);
+    self.m_svc = imm;
+    self.m_in_svc = true;
+    return 1;
+}
+
+void ArmScarletNx32::Coprocessor(SnxArmCPU* cpu, u32 word) {
+    auto& self = *reinterpret_cast<Cpu32*>(cpu)->parent;
+    const u32 coproc = (word >> 8) & 0xF;
+    const u32 crm = word & 0xF;
+
+    if (coproc == 15 && (word & 0x0F100010) == 0x0E000010) {
+        // MCR p15
+        const u32 opc1 = (word >> 21) & 7;
+        const u32 crn = (word >> 16) & 0xF;
+        const u32 opc2 = (word >> 5) & 7;
+        if (opc1 == 0 && crn == 7 && crm == 5 && opc2 == 4) {
+            // CP15_FLUSH_PREFETCH_BUFFER
+            return;
+        }
+        if (opc1 == 0 && crn == 7 && crm == 10 && (opc2 == 4 || opc2 == 5)) {
+            // CP15_DATA_SYNC_BARRIER, CP15_DATA_MEMORY_BARRIER
+            std::atomic_thread_fence(std::memory_order_seq_cst);
+            return;
+        }
+    } else if (coproc == 15 && (word & 0x0FF00000) == 0x0C500000) {
+        // MRRC p15
+        const u32 opc1 = (word >> 4) & 0xF;
+        const u32 rt = (word >> 12) & 0xF;
+        const u32 rt2 = (word >> 16) & 0xF;
+        if (opc1 == 0 && crm == 14) {
+            // CNTPCT
+            const u64 ticks = self.m_process->m_system.CoreTiming().GetClockTicks();
+            cpu->r[rt] = u32(ticks);
+            cpu->r[rt2] = u32(ticks >> 32);
+            return;
+        }
+    }
+
+    // TPIDRURW and TPIDRURO, and undefined for anything else.
+    snx_arm_coproc_user(cpu, word);
+    ASSERT(cpu->exit == SNX_ARM_OK && "unhandled coproc");
+}
+
+HaltReason ArmScarletNx32::RunThread(Kernel::KThread* thread) {
+    if (m_interrupt.exchange(false)) {
+        return HaltReason::BreakLoop;
+    }
+
+    // The block cache only covers the code present when it was made.
+    const u64 generation = m_process->CodeGeneration();
+    if (!m_module || generation != m_code_generation) {
+        snx_recompiled32_free(m_module);
+        m_module = m_process->MakeModule32();
+        m_code_generation = generation;
+    }
+
+    LoadCpu();
+    m_in_svc = false;
+    m_fault_scope.last_fault = ~u64{};
+    SetScarletNxFaultScope(&m_fault_scope);
+    if (sigsetjmp(m_fault_scope.env, 1) != 0) {
+        SetScarletNxFaultScope(nullptr);
+        LOG_CRITICAL(Core_ARM, "invalid memory access at {:#x}",
+                     m_fault_scope.fault_address);
+        SaveCpu();
+        return HaltReason::PrefetchAbort;
+    }
+    const int exit =
+        m_module ? snx_recompiled32_run(m_module, &m_cpu.cpu, &Svc, this) : SNX_ARM_BAD_ENTRY;
+    SetScarletNxFaultScope(nullptr);
+
+    SaveCpu();
+    return Halt(exit);
+}
+
+HaltReason ArmScarletNx32::Halt(int exit) {
+    if (m_in_svc) {
+        return HaltReason::SupervisorCall;
+    }
+    u32 const pc = m_cpu.cpu.r[15];
+    u32 const syndrome = m_cpu.cpu.syndrome;
+    switch (u32(exit)) {
+    case InterruptExit:
+        m_interrupt.store(false);
+        return HaltReason::BreakLoop;
+    case SNX_ARM_BREAKPOINT:
+        // As Dynarmic does without a debugger: report it and go on.
+        LOG_CRITICAL(Core_ARM, "BKPT #{:#x} at {:#x}", syndrome, pc);
+        return HaltReason::BreakLoop;
+    default:
+        LOG_CRITICAL(Core_ARM, "A32 exit {} at {:#x} (syndrome {:#x})", exit, pc, syndrome);
+        return HaltReason::PrefetchAbort;
+    }
+}
+
+HaltReason ArmScarletNx32::StepThread(Kernel::KThread* thread) {
+    // Never reached: the debugger selects Dynarmic.
+    LOG_ERROR(Core_ARM, "ScarletNX cannot single step");
+    return HaltReason::BreakLoop;
+}
+
+void ArmScarletNx32::LoadCpu() {
+    auto& cpu = m_cpu.cpu;
+    static_assert(sizeof(cpu.d) <= sizeof(m_ctx.v));
+    for (std::size_t i = 0; i < 16; i++)
+        cpu.r[i] = u32(m_ctx.r[i]);
+    cpu.cpsr = (m_ctx.pstate & ~ModeMask) | UserMode;
+    std::memcpy(cpu.d, m_ctx.v.data(), sizeof(cpu.d));
+    cpu.fpscr = FpsrFpcrToFpscr(m_ctx.fpsr, m_ctx.fpcr);
+    cpu.tpidrurw = u32(m_ctx.tpidr);
+    cpu.tpidruro = m_tpidrro;
+    cpu.exclusive_valid = 0;
+}
+
+void ArmScarletNx32::SaveCpu() {
+    const auto& cpu = m_cpu.cpu;
+    for (std::size_t i = 0; i < 16; i++)
+        m_ctx.r[i] = cpu.r[i];
+    m_ctx.fp = cpu.r[11];
+    m_ctx.sp = cpu.r[13];
+    m_ctx.lr = cpu.r[14];
+    m_ctx.pc = cpu.r[15];
+    m_ctx.pstate = cpu.cpsr;
+    std::memcpy(m_ctx.v.data(), cpu.d, sizeof(cpu.d));
+    const auto [fpsr, fpcr] = FpscrToFpsrFpcr(cpu.fpscr);
+    m_ctx.fpsr = fpsr;
+    m_ctx.fpcr = fpcr;
+    m_ctx.tpidr = cpu.tpidrurw;
+}
+
+void ArmScarletNx32::GetContext(Kernel::Svc::ThreadContext& ctx) const {
+    ctx = m_ctx;
+}
+
+void ArmScarletNx32::SetContext(const Kernel::Svc::ThreadContext& ctx) {
+    m_ctx = ctx;
+}
+
+void ArmScarletNx32::SetTpidrroEl0(u64 value) {
+    m_tpidrro = u32(value);
+}
+
+void ArmScarletNx32::GetSvcArguments(std::span<uint64_t, 8> args) const {
+    for (std::size_t i = 0; i < args.size(); i++)
+        args[i] = u32(m_ctx.r[i]);
+}
+
+void ArmScarletNx32::SetSvcArguments(std::span<const uint64_t, 8> args) {
+    for (std::size_t i = 0; i < args.size(); i++)
+        m_ctx.r[i] = u32(args[i]);
+}
+
+u32 ArmScarletNx32::GetSvcNumber() const {
+    return m_svc;
+}
+
+void ArmScarletNx32::SignalInterrupt(Kernel::KThread* thread) {
+    // The run loop checks the exit between blocks. A block's own exit takes precedence.
+    m_interrupt.store(true);
+    u32 expected = SNX_ARM_OK;
+    __atomic_compare_exchange_n(&m_cpu.cpu.exit, &expected, InterruptExit, false, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED);
+}
+
+void ArmScarletNx32::ClearInstructionCache() {
+    m_process->ClearInstructionCache();
+}
+
+void ArmScarletNx32::InvalidateCacheRange(u64 addr, std::size_t size) {
+    m_process->InvalidateCacheRange(addr, size);
+}
+
+} // namespace Core

src/core/arm/scarletnx/arm_scarletnx_32.h

@@ -0,0 +1,81 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include <atomic>
+#include <memory>
+
+#include "core/arm/arm_interface.h"
+#include "core/arm/scarletnx/scarletnx_api.h"
+#include "core/arm/scarletnx/scarletnx_process.h"
+
+namespace Core {
+
+/// Runs A32 and Thumb code through ScarletNX's block compiler. Blocks return to the run loop, so
+/// an SVC ends the run with r15 past it. The block cache is not thread-safe, so each core has its
+/// own, rebuilt when the process' code changes.
+class ArmScarletNx32 final : public ArmInterface {
+public:
+    ArmScarletNx32(std::shared_ptr<ScarletNxProcess> process, std::size_t core_index);
+    ~ArmScarletNx32() override;
+
+    Architecture GetArchitecture() const override {
+        return Architecture::AArch32;
+    }
+
+    HaltReason RunThread(Kernel::KThread* thread) override;
+    HaltReason StepThread(Kernel::KThread* thread) override;
+
+    void GetContext(Kernel::Svc::ThreadContext& ctx) const override;
+    void SetContext(const Kernel::Svc::ThreadContext& ctx) override;
+    void SetTpidrroEl0(u64 value) override;
+
+    void GetSvcArguments(std::span<uint64_t, 8> args) const override;
+    void SetSvcArguments(std::span<const uint64_t, 8> args) override;
+    u32 GetSvcNumber() const override;
+
+    void SignalInterrupt(Kernel::KThread* thread) override;
+    void ClearInstructionCache() override;
+    void InvalidateCacheRange(u64 addr, std::size_t size) override;
+
+protected:
+    const Kernel::DebugWatchpoint* HaltedWatchpoint() const override {
+        return nullptr;
+    }
+
+    void RewindBreakpointInstruction() override {}
+
+private:
+    // The CPU first, so the coprocessor hook can find its interface.
+    struct Cpu32 {
+        SnxArmCPU cpu;
+        ArmScarletNx32* parent;
+    };
+
+    static int Svc(void* context, u32 imm, u64 number, const u64 arguments[6]);
+    static void Coprocessor(SnxArmCPU* cpu, u32 word);
+    HaltReason Halt(int exit);
+    void LoadCpu();
+    void SaveCpu();
+
+    std::shared_ptr<ScarletNxProcess> m_process;
+    std::size_t m_core_index{};
+
+    snx_recompiled32* m_module{};
+    u64 m_code_generation{~u64{}};
+
+    // The context the kernel reads and writes; m_cpu holds it while guest code runs.
+    Kernel::Svc::ThreadContext m_ctx{};
+    u32 m_tpidrro{};
+    Cpu32 m_cpu{};
+    SnxArmRt m_rt{};
+
+    bool m_in_svc{};
+    u32 m_svc{};
+    std::atomic<bool> m_interrupt{};
+
+    ScarletNxFaultScope m_fault_scope{};
+};
+
+} // namespace Core

src/core/arm/scarletnx/arm_scarletnx_64.cpp

@@ -0,0 +1,261 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <cstring>
+
+#include <sys/mman.h>
+
+#include "common/assert.h"
+#include "common/literals.h"
+#include "common/logging.h"
+#include "core/arm/scarletnx/arm_scarletnx_64.h"
+#include "core/hle/kernel/k_thread.h"
+#include "core/hle/kernel/k_process.h"
+
+namespace Core {
+
+namespace {
+
+using namespace Common::Literals;
+namespace ctx = boost::context::detail;
+
+// Reserved, not committed: guest calls nest on it, and recompiling a region runs on it too.
+constexpr std::size_t StackSize = 32_MiB;
+constexpr std::size_t GuardSize = 64_KiB;
+
+bool SameContext(const Kernel::Svc::ThreadContext a, const Kernel::Svc::ThreadContext b, bool in_svc) {
+    // An SVC returns its results in x0-x7.
+    for (std::size_t i = in_svc ? 8 : 0; i < a.r.size(); i++)
+        if (a.r[i] != b.r[i])
+            return false;
+    return a.fp == b.fp && a.lr == b.lr && a.sp == b.sp && a.pc == b.pc
+        && (a.pstate >> 28) == (b.pstate >> 28) && a.v == b.v && a.fpcr == b.fpcr
+        && a.fpsr == b.fpsr && a.tpidr == b.tpidr;
+}
+
+} // namespace
+
+const RtAPI* ArmScarletNx64::Runtime() {
+    // this incurs a cost each time we call Runtime() -- but we only ever call it once (ideally)
+    static const RtAPI rt = [] {
+        RtAPI api;
+        snx_runtime_defaults(&api);
+        api.svc = &Svc;
+        api.undef = &Undefined;
+        api.brk = &Breakpoint;
+        api.poll = &Poll;
+        api.miss = &Miss;
+        api.code_changed = &CodeChanged;
+        api.ticks = &ScarletNxTicks;
+        return api;
+    }();
+    return &rt;
+}
+
+ArmScarletNx64::ArmScarletNx64(std::shared_ptr<ScarletNxProcess> process, std::size_t core_index)
+    : ArmInterface{true}
+    , m_process{std::move(process)}, m_core_index{core_index}
+{
+    // can't use virtualbuffer...
+    void* const stack = mmap(nullptr, StackSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    ASSERT_MSG(stack != MAP_FAILED, "cannot allocate a guest stack");
+    m_stack = static_cast<u8*>(stack);
+    mprotect(m_stack, GuardSize, PROT_NONE);
+
+    m_cpu.mem = m_process->m_arena;
+    m_cpu.rt = Runtime();
+    m_cpu.thread = this;
+
+    m_fault_scope.memory = &m_process->m_process.GetMemory();
+    m_fault_scope.arena = m_process->m_arena;
+    m_fault_scope.arena_size = ScarletNxProcess::ArenaSize;
+}
+
+ArmScarletNx64::~ArmScarletNx64() {
+    munmap(m_stack, StackSize);
+}
+
+void ArmScarletNx64::Svc(CPU* cpu, u32 imm) {
+    auto& self = From(cpu);
+    self.m_svc = imm;
+    self.Yield(HaltReason::SupervisorCall, true, true);
+}
+
+void ArmScarletNx64::Undefined(CPU* cpu, u64 pc, u32 word) {
+    // A reserved encoding rejected from inside an instruction, which then goes on.
+    if (cpu->pc != pc) {
+        LOG_ERROR(Core_ARM, "reserved encoding {:08X} at {:#x}", word, pc);
+        return;
+    }
+    LOG_CRITICAL(Core_ARM, "cannot execute {:08X} at {:#x}", word, pc);
+    From(cpu).Yield(HaltReason::PrefetchAbort, false, false);
+    UNREACHABLE();
+}
+
+void ArmScarletNx64::Breakpoint(CPU* cpu, u64 pc, u32 imm) {
+    // As Dynarmic does without a debugger: report it and go on.
+    LOG_CRITICAL(Core_ARM, "BRK #{:#x} at {:#x}", imm, pc);
+    cpu->pc = pc + 4;
+}
+
+void ArmScarletNx64::Poll(CPU* cpu) {
+    auto& self = From(cpu);
+    __atomic_store_n(&cpu->poll, 0, __ATOMIC_RELAXED);
+    if (self.m_interrupt.exchange(false))
+        self.Yield(HaltReason::BreakLoop, true, false);
+}
+
+void ArmScarletNx64::Miss(CPU* cpu, u64 pc) {
+    auto& process = *From(cpu).m_process;
+    const auto function = process.Lookup(pc);
+    if (!function) {
+        cpu->pc = pc;
+        Undefined(cpu, pc, 0);
+        return;
+    }
+    // The first region was recompiled by this lookup: dispatch through its table from now on.
+    if (snx_recompiled* const module = cpu->disp ? nullptr : process.FindModule(pc))
+        snx_recompiled_bind(module, cpu);
+    function(cpu, pc);
+}
+
+void ArmScarletNx64::CodeChanged(CPU* cpu, u64 addr) {
+    constexpr u64 ICacheLineSize = 64;
+    From(cpu).m_process->InvalidateCacheRange(addr & ~(ICacheLineSize - 1), ICacheLineSize);
+}
+
+void ArmScarletNx64::Entry(ctx::transfer_t transfer) {
+    auto* const self = static_cast<ArmScarletNx64*>(transfer.data);
+    self->m_host = transfer.fctx;
+    self->Execute();
+}
+
+void ArmScarletNx64::Execute() {
+    if (sigsetjmp(m_fault_scope.env, 1) != 0) {
+        LOG_CRITICAL(Core_ARM, "invalid memory access at {:#x}", m_fault_scope.fault_address);
+        Yield(HaltReason::PrefetchAbort, false, false);
+        UNREACHABLE();
+    }
+
+    // Every guest return to below the first frame comes back here.
+    while (true)
+        snx_lookup(&m_cpu, m_cpu.pc)(&m_cpu, m_cpu.pc);
+}
+
+void ArmScarletNx64::Yield(HaltReason reason, bool resumable, bool in_svc) {
+    m_halt = reason;
+    m_resumable = resumable;
+    m_suspended_in_svc = in_svc;
+    m_host = ctx::jump_fcontext(m_host, nullptr).fctx;
+}
+
+void ArmScarletNx64::ResetGuest() {
+    m_guest = ctx::make_fcontext(m_stack + StackSize, StackSize - GuardSize, &Entry);
+    if (snx_recompiled* const module = m_process->FindModule(m_cpu.pc))
+        snx_recompiled_bind(module, &m_cpu);
+}
+
+HaltReason ArmScarletNx64::RunThread(Kernel::KThread* thread) {
+    if (m_interrupt.exchange(false))
+        return HaltReason::BreakLoop;
+
+    bool const resume = m_resumable && m_suspended_thread_id == thread->GetThreadId() && SameContext(m_ctx, m_suspended_ctx, m_suspended_in_svc);
+    LoadCpu();
+    if (!resume)
+        ResetGuest();
+
+    m_resumable = false;
+    m_fault_scope.last_fault = ~u64{};
+    SetScarletNxFaultScope(&m_fault_scope);
+    m_guest = ctx::jump_fcontext(m_guest, this).fctx;
+    SetScarletNxFaultScope(nullptr);
+
+    SaveCpu();
+    if (m_resumable) {
+        m_suspended_thread_id = thread->GetThreadId();
+        m_suspended_ctx = m_ctx;
+    }
+    return m_halt;
+}
+
+HaltReason ArmScarletNx64::StepThread(Kernel::KThread* thread) {
+    // Never reached: the debugger selects Dynarmic.
+    LOG_ERROR(Core_ARM, "ScarletNX cannot single step");
+    return HaltReason::BreakLoop;
+}
+
+void ArmScarletNx64::LoadCpu() {
+    static_assert(sizeof(m_cpu.v) == sizeof(m_ctx.v));
+    for (std::size_t i = 0; i < m_ctx.r.size(); i++)
+        m_cpu.x[i] = m_ctx.r[i];
+    m_cpu.x[29] = m_ctx.fp;
+    m_cpu.x[30] = m_ctx.lr;
+    m_cpu.x[31] = m_ctx.sp;
+    m_cpu.pc = m_ctx.pc;
+    set_nzcv(&m_cpu, m_ctx.pstate >> 28);
+    std::memcpy(m_cpu.v, m_ctx.v.data(), sizeof(m_cpu.v));
+    m_cpu.fpcr = m_ctx.fpcr;
+    m_cpu.fpsr = m_ctx.fpsr;
+    m_cpu.tpidr = m_ctx.tpidr;
+    m_cpu.tpidrro = m_tpidrro;
+    m_cpu.excl_on = 0;
+}
+
+void ArmScarletNx64::SaveCpu() {
+    for (std::size_t i = 0; i < m_ctx.r.size(); i++) {
+        m_ctx.r[i] = m_cpu.x[i];
+    }
+    m_ctx.fp = m_cpu.x[29];
+    m_ctx.lr = m_cpu.x[30];
+    m_ctx.sp = m_cpu.x[31];
+    m_ctx.pc = m_cpu.pc;
+    m_ctx.pstate = get_nzcv(&m_cpu);
+    std::memcpy(m_ctx.v.data(), m_cpu.v, sizeof(m_cpu.v));
+    m_ctx.fpcr = m_cpu.fpcr;
+    m_ctx.fpsr = m_cpu.fpsr;
+    m_ctx.tpidr = m_cpu.tpidr;
+}
+
+void ArmScarletNx64::GetContext(Kernel::Svc::ThreadContext& ctx) const {
+    ctx = m_ctx;
+}
+
+void ArmScarletNx64::SetContext(const Kernel::Svc::ThreadContext& ctx) {
+    m_ctx = ctx;
+}
+
+void ArmScarletNx64::SetTpidrroEl0(u64 value) {
+    m_tpidrro = value;
+}
+
+void ArmScarletNx64::GetSvcArguments(std::span<uint64_t, 8> args) const {
+    for (std::size_t i = 0; i < args.size(); i++) {
+        args[i] = m_ctx.r[i];
+    }
+}
+
+void ArmScarletNx64::SetSvcArguments(std::span<const uint64_t, 8> args) {
+    for (std::size_t i = 0; i < args.size(); i++) {
+        m_ctx.r[i] = args[i];
+    }
+}
+
+u32 ArmScarletNx64::GetSvcNumber() const {
+    return m_svc;
+}
+
+void ArmScarletNx64::SignalInterrupt(Kernel::KThread* thread) {
+    // Generated code reads poll on backward branches and calls Poll, which yields.
+    m_interrupt.store(true);
+    __atomic_store_n(&m_cpu.poll, 1, __ATOMIC_RELAXED);
+}
+
+void ArmScarletNx64::ClearInstructionCache() {
+    m_process->ClearInstructionCache();
+}
+
+void ArmScarletNx64::InvalidateCacheRange(u64 addr, std::size_t size) {
+    m_process->InvalidateCacheRange(addr, size);
+}
+
+} // namespace Core

src/core/arm/scarletnx/arm_scarletnx_64.h

@@ -0,0 +1,100 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include <atomic>
+#include <memory>
+
+#include <boost/context/detail/fcontext.hpp>
+
+#include "core/arm/arm_interface.h"
+#include "core/arm/scarletnx/scarletnx_api.h"
+#include "core/arm/scarletnx/scarletnx_process.h"
+
+namespace Core {
+
+/// Runs A64 code recompiled by ScarletNX.
+///
+/// A recompiled guest function is a host function that returns when the guest function returns,
+/// so guest calls nest on the host stack and an SVC cannot return from the generated code. Guest
+/// code therefore runs on a coroutine of this core, which the SVC and interrupt hooks suspend.
+/// When the kernel next runs the same thread with the same context, the coroutine resumes;
+/// otherwise its host frames are dropped and execution restarts at the new pc through dispatch.
+class ArmScarletNx64 final : public ArmInterface {
+public:
+    ArmScarletNx64(std::shared_ptr<ScarletNxProcess> process, std::size_t core_index);
+    ~ArmScarletNx64() override;
+
+    Architecture GetArchitecture() const override {
+        return Architecture::AArch64;
+    }
+
+    HaltReason RunThread(Kernel::KThread* thread) override;
+    HaltReason StepThread(Kernel::KThread* thread) override;
+
+    void GetContext(Kernel::Svc::ThreadContext& ctx) const override;
+    void SetContext(const Kernel::Svc::ThreadContext& ctx) override;
+    void SetTpidrroEl0(u64 value) override;
+
+    void GetSvcArguments(std::span<uint64_t, 8> args) const override;
+    void SetSvcArguments(std::span<const uint64_t, 8> args) override;
+    u32 GetSvcNumber() const override;
+
+    void SignalInterrupt(Kernel::KThread* thread) override;
+    void ClearInstructionCache() override;
+    void InvalidateCacheRange(u64 addr, std::size_t size) override;
+
+protected:
+    const Kernel::DebugWatchpoint* HaltedWatchpoint() const override {
+        return nullptr;
+    }
+
+    void RewindBreakpointInstruction() override {}
+
+private:
+    static ArmScarletNx64& From(CPU* cpu) {
+        return *static_cast<ArmScarletNx64*>(cpu->thread);
+    }
+    static const RtAPI* Runtime();
+
+    // Runtime hooks called by the generated code.
+    static void Svc(CPU* cpu, u32 imm);
+    static void Undefined(CPU* cpu, u64 pc, u32 word);
+    static void Breakpoint(CPU* cpu, u64 pc, u32 imm);
+    static void Poll(CPU* cpu);
+    static void Miss(CPU* cpu, u64 pc);
+    static void CodeChanged(CPU* cpu, u64 addr);
+
+    static void Entry(boost::context::detail::transfer_t transfer);
+    [[noreturn]] void Execute();
+    void Yield(HaltReason reason, bool resumable, bool in_svc);
+    void ResetGuest();
+    void LoadCpu();
+    void SaveCpu();
+
+    std::shared_ptr<ScarletNxProcess> m_process;
+    std::size_t m_core_index{};
+
+    // The context the kernel reads and writes; m_cpu holds it while guest code runs.
+    Kernel::Svc::ThreadContext m_ctx{};
+    u64 m_tpidrro{};
+    CPU m_cpu{};
+
+    HaltReason m_halt{};
+    u32 m_svc{};
+    std::atomic<bool> m_interrupt{};
+
+    // The coroutine, and what it was suspended in, when it can be resumed.
+    boost::context::detail::fcontext_t m_guest{};
+    boost::context::detail::fcontext_t m_host{};
+    u8* m_stack{};
+    bool m_resumable{};
+    bool m_suspended_in_svc{};
+    u64 m_suspended_thread_id{};
+    Kernel::Svc::ThreadContext m_suspended_ctx{};
+
+    ScarletNxFaultScope m_fault_scope{};
+};
+
+} // namespace Core

src/core/arm/scarletnx/scarletnx_api.h

@@ -0,0 +1,10 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+// snx_recompiler.h includes cpu.h and arm.h before its own extern "C" block, so the whole
+// header needs C linkage for the runtime library's functions to resolve.
+extern "C" {
+#include <scarletnx/snx_recompiler.h>
+}

src/core/arm/scarletnx/scarletnx_process.cpp

@@ -0,0 +1,300 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <algorithm>
+#include <mutex>
+
+#include <signal.h>
+
+#include "common/fs/path_util.h"
+#include "common/logging.h"
+#include "common/settings.h"
+#include "core/arm/scarletnx/arm_scarletnx_32.h"
+#include "core/arm/scarletnx/arm_scarletnx_64.h"
+#include "core/arm/scarletnx/scarletnx_api.h"
+#include "core/arm/scarletnx/scarletnx_process.h"
+#include "core/core.h"
+#include "core/core_timing.h"
+#include "core/device_memory.h"
+#include "core/hle/kernel/k_process.h"
+#include "core/hle/kernel/kernel.h"
+#include "core/memory.h"
+
+namespace Core {
+
+namespace {
+
+// ScarletNX refuses dispatch tables spanning more than 1 GiB of guest code.
+constexpr u64 MaxModuleSpan = 1ULL << 30;
+constexpr u64 A32Limit = 1ULL << 32;
+
+std::atomic<Timing::CoreTiming*> g_core_timing{};
+
+// Needs be TLS because SNX expects like, more than 4 threads (host == guest threads)
+// and well -- quite impervious to "emulated" threads... maybe one day this can be removed
+thread_local ScarletNxFaultScope* g_fault_scope{};
+static struct {
+    struct sigaction old_sigsegv;
+    struct sigaction old_sigbus;
+    std::once_flag installed;
+} g_snx_data;
+
+bool Overlaps(const ScarletNxProcess::CodeRange& range, u64 addr, u64 size) {
+    return addr < range.addr + range.size && range.addr < addr + size;
+}
+
+void ChainSignal(int sig, siginfo_t* info, void* raw_context) {
+    const struct sigaction& old = sig == SIGSEGV ? g_snx_data.old_sigsegv : g_snx_data.old_sigbus;
+    if (old.sa_flags & SA_SIGINFO) {
+        old.sa_sigaction(sig, info, raw_context);
+    } else if (old.sa_handler == SIG_DFL) {
+        // The faulting instruction runs again and takes the default action.
+        signal(sig, SIG_DFL);
+    } else if (old.sa_handler != SIG_IGN) {
+        old.sa_handler(sig);
+    }
+}
+
+void FaultHandler(int sig, siginfo_t* info, void* raw_context) {
+    ScarletNxFaultScope* const scope = g_fault_scope;
+    u8* const addr = static_cast<u8*>(info->si_addr);
+    if (!scope || addr < scope->arena || addr >= scope->arena + scope->arena_size) {
+        ChainSignal(sig, info, raw_context);
+        return;
+    }
+
+    // Pages the rasterizer protects fault on access: invalidate them and retry. A second fault at
+    // the same addr means retrying will not help.
+    const u64 guest_address = u64(addr - scope->arena);
+    if (guest_address != scope->last_fault) {
+        scope->last_fault = guest_address;
+        if (scope->memory->InvalidateNCE(guest_address & ~Memory::YUZU_PAGEMASK, Memory::YUZU_PAGESIZE)) {
+            return;
+        }
+    }
+    scope->fault_address = guest_address;
+    siglongjmp(scope->env, 1);
+}
+
+} // namespace
+
+void InstallScarletNxFaultHandler() {
+    std::call_once(g_snx_data.installed, [] {
+        struct sigaction action {};
+        action.sa_flags = SA_SIGINFO;
+        action.sa_sigaction = &FaultHandler;
+        sigemptyset(&action.sa_mask);
+        sigaction(SIGSEGV, &action, &g_snx_data.old_sigsegv);
+        sigaction(SIGBUS, &action, &g_snx_data.old_sigbus);
+    });
+}
+
+void SetScarletNxFaultScope(ScarletNxFaultScope* scope) {
+    g_fault_scope = scope;
+}
+
+u64 ScarletNxTicks() {
+    return g_core_timing.load(std::memory_order_relaxed)->GetClockTicks();
+}
+
+std::unique_ptr<ArmInterface> MakeScarletNxInterface(std::shared_ptr<ScarletNxProcess> process, bool is_64bit, std::size_t core_index) {
+    if (is_64bit)
+        return std::make_unique<ArmScarletNx64>(std::move(process), core_index);
+    return std::make_unique<ArmScarletNx32>(std::move(process), core_index);
+}
+
+ScarletNxProcess::ScarletNxProcess(System& system, Kernel::KProcess& process)
+    : m_system{system}
+    , m_process{process}
+    , m_arena{system.DeviceMemory().buffer.VirtualBasePointer()}
+{
+    InstallScarletNxFaultHandler();
+    g_core_timing.store(&system.CoreTiming(), std::memory_order_relaxed);
+
+    m_recompiler = snx_recompiler_new(SNX_RECOMPILER_FLAG_LLVM);
+    ASSERT(m_recompiler && "cannot create the recompiler");
+
+    // Linked modules are kept by a hash of their code, so later launches skip the recompile.
+    const auto cache = Common::FS::GetEdenPath(Common::FS::EdenPath::CacheDir) / "scarletnx";
+    if (snx_recompiler_set_cache(m_recompiler, Common::FS::PathToUTF8String(cache).c_str()) != 0)
+        LOG_WARNING(Core_ARM, "no code cache: {}", snx_recompiler_error(m_recompiler));
+}
+
+ScarletNxProcess::~ScarletNxProcess() {
+    for (auto& mod : m_modules)
+        snx_recompiled_free(mod.mod);
+    snx_recompiler_free(m_recompiler);
+}
+
+bool ScarletNxProcess::ShouldUse(System& system, const Kernel::KProcess& process) {
+    if (Settings::values.cpu_backend.GetValue() != Settings::CpuBackend::ScarletNx)
+        return false;
+    auto const f = [](auto& s) {
+        LOG_WARNING(Core_ARM, "snx: {}", s);
+        return false;
+    };
+    if (!process.IsApplication())
+        return f("no qlaunch yet");
+    if (!system.Kernel().IsMulticore())
+        return f("single core mode needs cycle counting");
+    if (system.DebuggerEnabled())
+        return f("the debugger needs stepping and watchpoints");
+    /// ScarletNX expects flat memory, so it will only work with fastmem
+    if (!Settings::IsFastmemEnabled() || !system.DeviceMemory().buffer.VirtualBasePointer())
+        return f("guest memory must be mapped by fastmem");
+    if (snx_recompiler_abi() != SNX_ABI)
+        return f("the library was built with a different ABI");
+    if (!snx_recompiler_has(SNX_RECOMPILER_FLAG_LLVM))
+        return f("LLVM cannot target this host");
+    return true;
+}
+
+std::vector<ScarletNxProcess::CodeRange> ScarletNxProcess::GetCodeRanges() const {
+    std::vector<CodeRange> r;
+    const auto& page_table = m_process.GetPageTable().GetBasePageTable();
+    u64 addr = GetInteger(page_table.GetAddressSpaceStart());
+    while (true) {
+        Kernel::KMemoryInfo info;
+        Kernel::Svc::PageInfo page_info;
+        if (page_table.QueryInfo(&info, &page_info, addr).IsError())
+            break;
+        if (True(info.GetPermission() & Kernel::KMemoryPermission::UserExecute)) {
+            if (!r.empty() && r.back().addr + r.back().size == info.GetAddress()) {
+                r.back().size += info.GetSize();
+            } else {
+                r.push_back({info.GetAddress(), info.GetSize()});
+            }
+        }
+        // The block past the addr space ends at 0.
+        if (info.GetEndAddress() <= addr)
+            break;
+        addr = info.GetEndAddress();
+    }
+    return r;
+}
+
+const ScarletNxProcess::Module* ScarletNxProcess::FindModuleLocked(u64 pc) const {
+    for (const auto& mod : m_modules) {
+        if (mod.retired || pc < mod.lo || pc >= mod.hi)
+            continue;
+        for (const auto& range : mod.ranges)
+            if (pc >= range.addr && pc < range.addr + range.size)
+                return &mod;
+    }
+    return nullptr;
+}
+
+snx_recompiled* ScarletNxProcess::RecompileRegionLocked(u64 pc) {
+    const auto r = GetCodeRanges();
+    const auto it = std::ranges::find_if(r, [pc](const CodeRange& range) {
+        return pc >= range.addr && pc < range.addr + range.size;
+    });
+    if (it == r.end())
+        return nullptr;
+
+    const auto is_covered = [this](const CodeRange& range) {
+        return std::ranges::any_of(m_modules, [&](const Module& mod) {
+            return !mod.retired && std::ranges::any_of(mod.ranges, [&](const CodeRange& cr) {
+                return Overlaps(cr, range.addr, range.size);
+            });
+        });
+    };
+
+    // Recompile as many neighbouring regions as one dispatch table can cover.
+    auto first = size_t(it - r.begin());
+    auto last = first;
+    const auto end_of = [&](size_t i) { return r[i].addr + r[i].size; };
+    while (first > 0 && !is_covered(r[first - 1]) && end_of(last) - r[first - 1].addr <= MaxModuleSpan)
+        --first;
+    while (last + 1 < r.size() && !is_covered(r[last + 1])
+    && end_of(last + 1) - r[first].addr <= MaxModuleSpan)
+        ++last;
+
+    Module mod{};
+    mod.ranges.assign(r.begin() + first, r.begin() + last + 1);
+    mod.lo = r[first].addr;
+    mod.hi = end_of(last);
+
+    std::vector<snx_code_range> code;
+    u64 code_size = 0;
+    for (const auto& range : mod.ranges) {
+        code.push_back({range.addr, m_arena + range.addr, range.size});
+        code_size += range.size;
+    }
+
+    LOG_INFO(Core_ARM, "recompiling {} KiB of code at {:#x}-{:#x}", code_size / 1024, mod.lo, mod.hi);
+    mod.mod = snx_recompile_ranges(m_recompiler, code.data(), code.size(), &pc, 1);
+    if (mod.mod) {
+        LOG_INFO(Core_ARM, "recompiled {} functions", snx_recompiled_functions(mod.mod));
+    } else {
+        // Kept, so the region is not recompiled again on every miss.
+        LOG_ERROR(Core_ARM, "recompilation failed: {}", snx_recompiler_error(m_recompiler));
+    }
+
+    m_modules.push_back(std::move(mod));
+    return m_modules.back().mod;
+}
+
+ScarletNxProcess::SnxGuestFn ScarletNxProcess::Lookup(u64 pc) {
+    snx_recompiled* mod;
+    {
+        std::scoped_lock lk{m_mutex};
+        const Module* const known = FindModuleLocked(pc);
+        mod = known ? known->mod : RecompileRegionLocked(pc);
+    }
+    if (!mod)
+        return nullptr;
+    // Waits for the mod's JIT when discovery missed the code at pc.
+    return snx_recompiled_lookup(mod, pc);
+}
+
+snx_recompiled* ScarletNxProcess::FindModule(u64 pc) {
+    std::scoped_lock lk{m_mutex};
+    const Module* const mod = FindModuleLocked(pc);
+    return mod ? mod->mod : nullptr;
+}
+
+snx_recompiled32* ScarletNxProcess::MakeModule32() {
+    std::scoped_lock lk{m_mutex};
+    std::vector<snx_code_range> code;
+    for (const auto& range : GetCodeRanges()) {
+        if (range.addr >= A32Limit) {
+            continue;
+        }
+        code.push_back({range.addr, nullptr, std::min(range.size, A32Limit - range.addr)});
+    }
+    if (code.empty())
+        return nullptr;
+    snx_recompiled32* const mod = snx_recompile32_ranges(m_recompiler, code.data(), code.size());
+    if (!mod)
+        LOG_ERROR(Core_ARM, "cannot prepare A32 code: {}", snx_recompiler_error(m_recompiler));
+    return mod;
+}
+
+void ScarletNxProcess::InvalidateCacheRange(u64 addr, u64 size) {
+    std::scoped_lock lk{m_mutex};
+    for (auto& mod : m_modules) {
+        if (mod.retired || !std::ranges::any_of(mod.ranges, [&](const CodeRange& range) {
+            return Overlaps(range, addr, size);
+        }))
+            continue;
+        // Running code diverts out of the retired functions, and the region is recompiled from
+        // the new code when it is next reached.
+        if (mod.mod)
+            snx_recompiled_invalidate(mod.mod, addr, size, nullptr, nullptr);
+        mod.retired = true;
+    }
+    m_code_generation.fetch_add(1, std::memory_order_release);
+}
+
+void ScarletNxProcess::ClearInstructionCache() {
+    std::scoped_lock lk{m_mutex};
+    for (auto& mod : m_modules) {
+        if (!mod.retired && mod.mod)
+            snx_recompiled_invalidate(mod.mod, mod.lo, mod.hi - mod.lo, nullptr, nullptr);
+        mod.retired = true;
+    }
+    m_code_generation.fetch_add(1, std::memory_order_release);
+}
+
+} // namespace Core

src/core/arm/scarletnx/scarletnx_process.h

@@ -0,0 +1,104 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include <atomic>
+#include <csetjmp>
+#include <memory>
+#include <mutex>
+#include <vector>
+
+#include "common/common_types.h"
+
+struct CPU;
+struct snx_recompiler;
+struct snx_recompiled;
+struct snx_recompiled32;
+
+namespace Kernel {
+class KProcess;
+}
+
+namespace Core::Memory {
+class Memory;
+}
+
+namespace Core {
+
+class ArmInterface;
+class System;
+
+class ScarletNxProcess {
+public:
+    using SnxGuestFn = void (*)(CPU*, u64);
+
+    // DeviceMemory reserves 39 bits of address space for the fastmem arena.
+    static constexpr u64 ArenaSize = 1ULL << 39;
+
+    struct CodeRange {
+        u64 addr;
+        u64 size;
+    };
+
+    ScarletNxProcess(System& system, Kernel::KProcess& process);
+    ~ScarletNxProcess();
+
+    static bool ShouldUse(System& system, const Kernel::KProcess& process);
+    SnxGuestFn Lookup(u64 pc);
+    snx_recompiled* FindModule(u64 pc);
+    snx_recompiled32* MakeModule32();
+
+    void InvalidateCacheRange(u64 addr, u64 size);
+    void ClearInstructionCache();
+
+    /// @brief general gate for when we are about to invalidate a given block aka. trigger regen
+    u64 CodeGeneration() const {
+        return m_code_generation.load(std::memory_order_acquire);
+    }
+
+    struct Module {
+        std::vector<CodeRange> ranges;
+        u64 lo;
+        u64 hi;
+        snx_recompiled* mod;
+        bool retired;
+    };
+
+    std::vector<CodeRange> GetCodeRanges() const;
+    const Module* FindModuleLocked(u64 pc) const;
+    snx_recompiled* RecompileRegionLocked(u64 pc);
+
+    std::vector<Module> m_modules;
+    std::atomic<u64> m_code_generation{};
+
+    // TODO: remove parent ref?
+    System& m_system;
+    Kernel::KProcess& m_process;
+    u8* m_arena{};
+    snx_recompiler* m_recompiler{};
+
+    // ScarletNX's recompiler is used by one thread at a time.
+    std::mutex m_mutex;
+};
+
+/// Recovers from host faults in guest memory on the thread running guest code: a fault on a
+/// page the rasterizer protects is resolved and retried, any other jumps to env.
+struct ScarletNxFaultScope {
+    sigjmp_buf env;
+    Memory::Memory* memory{};
+    u8* arena{};
+    u64 arena_size{};
+    u64 last_fault{~0ull};
+    u64 fault_address{};
+};
+
+void InstallScarletNxFaultHandler();
+void SetScarletNxFaultScope(ScarletNxFaultScope* scope);
+
+/// CNTPCT_EL0 of the emulated system.
+u64 ScarletNxTicks();
+
+std::unique_ptr<ArmInterface> MakeScarletNxInterface(std::shared_ptr<ScarletNxProcess> process, bool is_64bit, std::size_t core_index);
+
+} // namespace Core

src/core/crypto/ncz_decompressor.cpp

@@ -1,430 +0,0 @@
-// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
-// SPDX-License-Identifier: GPL-3.0-or-later
-
-#include <algorithm>
-#include <array>
-#include <cstring>
-#include <memory>
-#include <mutex>
-#include <optional>
-#include <span>
-#include <string>
-#include <vector>
-
-#include <zstd.h>
-
-#include "common/common_types.h"
-#include "common/logging.h"
-#include "common/zstd_compression.h"
-#include "core/crypto/aes_util.h"
-#include "core/crypto/key_manager.h"
-#include "core/crypto/ncz_decompressor.h"
-#include "core/file_sys/vfs/vfs.h"
-
-namespace Core::Crypto {
-
-namespace {
-
-constexpr u64 HeaderSize = 0x4000;
-constexpr std::size_t SectionWire = 0x40;
-constexpr std::size_t BlockFixed = 0x18;
-constexpr std::size_t Chunk = 0x100000;
-// Upper bound on NCZ section entries (64 bytes each, so the table is at most 4 MiB). A base NCA
-// has a handful of sections, but nsz stores an update's patch (BKTR) data one entry per
-// subsection, which is thousands of them.
-constexpr u64 MaxSectionCount = 0x10000;
-constexpr std::array<u8, 8> SectionsMagic{'N', 'C', 'Z', 'S', 'E', 'C', 'T', 'N'};
-constexpr std::array<u8, 8> BlockMagic{'N', 'C', 'Z', 'B', 'L', 'O', 'C', 'K'};
-
-struct Section {
-    s64 offset, size;
-    u64 crypto_type;
-    Key128 key, counter;
-    bool Ctr() const { return crypto_type == 3 || crypto_type == 4; }
-};
-
-struct BlockHeader {
-    u32 exponent;
-    u64 decompressed_size;
-    std::vector<u32> sizes;
-};
-
-u64 Le(const u8* p, std::size_t n) {
-    u64 v = 0;
-    for (std::size_t i = n; i-- > 0;) v = (v << 8) | p[i];
-    return v;
-}
-
-// Mirrors nsz AESCTR.seek(): upper 8 bytes = stored counter, lower 8 = absolute NCA offset / 16.
-void SetIv(Key128& iv, const Key128& base, u64 off) {
-    iv = base;
-    u64 blk = off >> 4;
-    for (std::size_t i = 0; i < 8; ++i) { iv[15 - i] = static_cast<u8>(blk & 0xFF); blk >>= 8; }
-}
-
-// Parse header + section table + optional block header. Returns payload_start.
-std::optional<std::pair<std::vector<Section>, std::optional<BlockHeader>>> ParseHeader(
-    const FileSys::VirtualFile& f, u64& payload_start) {
-    const u64 fsize = f->GetSize();
-    if (fsize < HeaderSize + 16) return std::nullopt;
-
-    const auto head = f->ReadBytes(16, HeaderSize);
-    if (head.size() != 16 || !std::equal(head.begin(), head.begin() + 8, SectionsMagic.begin()))
-        return std::nullopt;
-    const u64 count = Le(head.data() + 8, 8);
-    if (count == 0 || count > MaxSectionCount || count * SectionWire > fsize - HeaderSize - 16)
-        return std::nullopt;
-
-    const auto table = f->ReadBytes(count * SectionWire, HeaderSize + 16);
-    if (table.size() != count * SectionWire) return std::nullopt;
-
-    std::vector<Section> sections;
-    sections.reserve(count + 1);
-    for (u64 i = 0; i < count; ++i) {
-        const u8* e = table.data() + i * SectionWire;
-        Section s{};
-        s.offset = static_cast<s64>(Le(e, 8));
-        s.size = static_cast<s64>(Le(e + 8, 8));
-        s.crypto_type = Le(e + 16, 8);
-        std::memcpy(s.key.data(), e + 32, 16);
-        std::memcpy(s.counter.data(), e + 48, 16);
-        sections.push_back(s);
-    }
-
-    const u64 block_start = HeaderSize + 16 + count * SectionWire;
-    const auto fixed = f->ReadBytes(BlockFixed, block_start);
-    std::optional<BlockHeader> bh;
-    if (fixed.size() == BlockFixed &&
-        std::equal(fixed.begin(), fixed.begin() + 8, BlockMagic.begin())) {
-        BlockHeader b{};
-        b.exponent = fixed[11];
-        const s32 n = static_cast<s32>(Le(fixed.data() + 12, 4));
-        if (n <= 0) return std::nullopt;
-        b.decompressed_size = Le(fixed.data() + 16, 8);
-        const auto sizes = f->ReadBytes(static_cast<u64>(n) * 4, block_start + BlockFixed);
-        if (sizes.size() != static_cast<u64>(n) * 4) return std::nullopt;
-        b.sizes.resize(n);
-        for (s32 i = 0; i < n; ++i) b.sizes[i] = static_cast<u32>(Le(sizes.data() + i * 4, 4));
-        payload_start = block_start + BlockFixed + static_cast<u64>(n) * 4;
-        bh = std::move(b);
-    } else {
-        payload_start = block_start;
-    }
-
-    if (!sections.empty() && sections[0].offset > static_cast<s64>(HeaderSize)) {
-        Section fake{};
-        fake.offset = static_cast<s64>(HeaderSize);
-        fake.size = sections[0].offset - static_cast<s64>(HeaderSize);
-        sections.insert(sections.begin(), fake);
-    }
-    return std::make_pair(std::move(sections), std::move(bh));
-}
-
-// Sequential reader over independently-compressed blocks, one block cached (like nsz_rs).
-class BlockReader {
-public:
-    BlockReader(FileSys::VirtualFile f, const BlockHeader& bh, u64 payload_start)
-        : source{std::move(f)}, block_size{1ULL << bh.exponent}, sizes{bh.sizes},
-          decompressed_size{bh.decompressed_size} {
-        if (bh.exponent < 14 || bh.exponent > 32 || sizes.empty())
-            throw std::runtime_error("bad NCZBLOCK header");
-        u64 off = payload_start;
-        offsets.reserve(sizes.size());
-        for (u32 s : sizes) { offsets.push_back(off); off += s; }
-    }
-
-    // Fills `out` from `position`; returns bytes written.
-    std::size_t ReadAt(u64 position, std::span<u8> out) {
-        std::size_t done = 0;
-        while (done < out.size() && position < decompressed_size) {
-            const u64 id = position / block_size;
-            if (id >= sizes.size()) break;
-            if (cache_id != id && !Load(id)) break;
-            const u64 in = position - id * block_size;
-            const std::size_t n = static_cast<std::size_t>(
-                std::min<u64>(out.size() - done, cache.size() - in));
-            std::memcpy(out.data() + done, cache.data() + in, n);
-            done += n;
-            position += n;
-        }
-        return done;
-    }
-
-private:
-    bool Load(u64 id) {
-        u64 want = block_size;
-        if (id + 1 == sizes.size()) {
-            const u64 rem = decompressed_size % block_size;
-            if (rem > 0) want = rem; // avoid the 0-size bug from the original nsz
-        }
-        try { cache.resize(static_cast<std::size_t>(want)); }
-        catch (const std::bad_alloc&) { return false; }
-        const u32 csize = sizes[id];
-        if (csize < want) {
-            const auto comp = source->ReadBytes(csize, offsets[id]);
-            if (comp.size() != csize ||
-                Common::Compression::DecompressDataZSTD(comp, cache) != want) return false;
-        } else if (source->Read(cache.data(), cache.size(), offsets[id]) != cache.size()) {
-            return false;
-        }
-        cache_id = id;
-        return true;
-    }
-
-    FileSys::VirtualFile source;
-    u64 block_size;
-    std::vector<u64> offsets;
-    std::vector<u32> sizes;
-    u64 decompressed_size;
-    u64 cache_id = ~0ULL;
-    std::vector<u8> cache;
-};
-
-class BlockNczFile final : public FileSys::VfsFile {
-public:
-    BlockNczFile(std::string name_, std::vector<u8> hdr_, std::vector<Section> sections_,
-                 std::unique_ptr<BlockReader> body_)
-        : name{std::move(name_)}, hdr{std::move(hdr_)}, sections{std::move(sections_)},
-          body{std::move(body_)} {
-        nca_size = HeaderSize;
-        for (const auto& s : sections)
-            nca_size = std::max<u64>(nca_size, static_cast<u64>(s.offset + s.size));
-        ciphers.reserve(sections.size());
-        for (const auto& s : sections)
-            ciphers.push_back(s.Ctr() ? std::make_unique<AESCipher<Key128>>(s.key, Mode::CTR)
-                                      : nullptr);
-    }
-
-    std::string GetName() const override { return name; }
-    std::size_t GetSize() const override { return static_cast<std::size_t>(nca_size); }
-    bool Resize(std::size_t) override { return false; }
-    FileSys::VirtualDir GetContainingDirectory() const override { return nullptr; }
-    bool IsWritable() const override { return false; }
-    bool IsReadable() const override { return true; }
-
-    std::size_t Read(u8* data, std::size_t len, std::size_t off) const override {
-        if (off >= nca_size) return 0;
-        len = static_cast<std::size_t>(std::min<u64>(len, nca_size - off));
-        const u64 end = off + len;
-        u64 pos = off;
-        if (pos < HeaderSize) {
-            const u64 n = std::min<u64>(end, HeaderSize) - pos;
-            std::memcpy(data, hdr.data() + pos, static_cast<std::size_t>(n));
-            pos += n;
-        }
-        std::scoped_lock lock{mutex};
-        for (std::size_t i = 0; i < sections.size() && pos < end; ++i) {
-            const auto& s = sections[i];
-            const u64 begin = std::max<u64>(static_cast<u64>(s.offset), HeaderSize);
-            const u64 stop = std::max<u64>(static_cast<u64>(s.offset + s.size), begin);
-            if (stop <= pos) continue;
-            if (pos < begin) {
-                const u64 g = std::min(end, begin);
-                std::memset(data + (pos - off), 0, static_cast<std::size_t>(g - pos));
-                pos = g;
-                if (pos >= end) break;
-            }
-            const u64 pe = std::min(end, stop);
-            const std::span<u8> piece(data + (pos - off), static_cast<std::size_t>(pe - pos));
-            if (body->ReadAt(pos - HeaderSize, piece) != piece.size())
-                return static_cast<std::size_t>(pos - off);
-            if (ciphers[i]) {
-                Key128 iv{};
-                SetIv(iv, s.counter, pos);
-                ciphers[i]->SetIV(iv);
-                ciphers[i]->Transcode(piece.data(), piece.size(), piece.data(), Op::Encrypt);
-            }
-            pos = pe;
-        }
-        return len;
-    }
-
-    std::size_t Write(const u8*, std::size_t, std::size_t) override { return 0; }
-    bool Rename(std::string_view) override { return false; }
-
-private:
-    const std::string name;
-    const std::vector<u8> hdr;
-    const std::vector<Section> sections;
-    const std::unique_ptr<BlockReader> body;
-    std::vector<std::unique_ptr<AESCipher<Key128>>> ciphers;
-    mutable std::mutex mutex;
-    u64 nca_size{};
-};
-
-// Solid NCZ: one zstd stream over the whole body. Decoded incrementally into memory, up to the
-// requested offset, so sequential install reads are O(n) instead of O(n^2).
-class SolidNczFile final : public FileSys::VfsFile {
-public:
-    SolidNczFile(std::string name_, FileSys::VirtualFile source_,
-                 std::vector<Section> sections_, u64 payload_start_)
-        : name{std::move(name_)}, source{std::move(source_)}, sections{std::move(sections_)},
-          payload_start{payload_start_} {
-        const auto raw_header = source->ReadBytes(HeaderSize, 0);
-        data.assign(raw_header.begin(), raw_header.end());
-        frontier = HeaderSize;
-    }
-
-    ~SolidNczFile() override {
-        if (stream != nullptr) ZSTD_freeDStream(stream);
-    }
-
-    std::string GetName() const override { return name; }
-    std::size_t GetSize() const override {
-        u64 size = HeaderSize;
-        for (const auto& s : sections)
-            size = std::max<u64>(size, static_cast<u64>(s.offset + s.size));
-        return static_cast<std::size_t>(size);
-    }
-    bool Resize(std::size_t) override { return false; }
-    FileSys::VirtualDir GetContainingDirectory() const override { return nullptr; }
-    bool IsWritable() const override { return false; }
-    bool IsReadable() const override { return true; }
-
-    std::size_t Read(u8* out, std::size_t len, std::size_t off) const override {
-        std::scoped_lock lock{mutex};
-        const u64 nca_size = GetSize();
-        if (off >= nca_size) return 0;
-        len = static_cast<std::size_t>(std::min<u64>(len, nca_size - off));
-        const u64 needed = off + len;
-        if (needed > frontier && !DecodeTo(needed)) return 0;
-        std::memcpy(out, data.data() + off, len);
-        return len;
-    }
-
-    std::size_t Write(const u8*, std::size_t, std::size_t) override { return 0; }
-    bool Rename(std::string_view) override { return false; }
-
-private:
-    bool DecodeTo(u64 needed) const {
-        if (stream == nullptr) {
-            stream = ZSTD_createDStream();
-            if (stream == nullptr) return false;
-            ZSTD_DCtx_setParameter(stream, ZSTD_d_windowLogMax, 31);
-            read_pos = payload_start;
-        }
-
-        const u64 file_size = source->GetSize();
-        std::vector<u8> out_buf(Chunk);
-
-        std::size_t index = 0;
-        for (; index < sections.size(); ++index) {
-            const auto& s = sections[index];
-            const u64 begin = std::max<u64>(static_cast<u64>(s.offset), HeaderSize);
-            const u64 end = std::max<u64>(static_cast<u64>(s.offset) + static_cast<u64>(s.size),
-                                          begin);
-            if (end > frontier) break;
-        }
-
-        for (; index < sections.size() && frontier < needed; ++index) {
-            const auto& s = sections[index];
-            const u64 begin = std::max<u64>(static_cast<u64>(s.offset), HeaderSize);
-            const u64 end = std::max<u64>(static_cast<u64>(s.offset) + static_cast<u64>(s.size),
-                                          begin);
-            if (end <= frontier) continue;
-            u64 pos = std::max<u64>(begin, frontier);
-
-            std::optional<AESCipher<Key128>> cipher;
-            if (s.Ctr()) cipher.emplace(s.key, Mode::CTR);
-
-            while (pos < end && frontier < needed) {
-                const u64 want = std::min<u64>(end - pos, out_buf.size());
-                std::size_t produced = 0;
-                while (produced < want) {
-                    if (in.pos >= in.size) {
-                        const u64 remaining = file_size - read_pos;
-                        const std::size_t chunk = static_cast<std::size_t>(
-                            std::min<u64>(Chunk, remaining));
-                        if (chunk == 0) { LOG_ERROR(Crypto, "Solid NCZ: truncated"); return false; }
-                        const auto bytes = source->ReadBytes(chunk, read_pos);
-                        if (bytes.empty()) { LOG_ERROR(Crypto, "Solid NCZ: truncated"); return false; }
-                        read_pos += bytes.size();
-                        in_buf.assign(bytes.begin(), bytes.end());
-                        in.src = in_buf.data();
-                        in.size = in_buf.size();
-                        in.pos = 0;
-                    }
-                    ZSTD_outBuffer outb{out_buf.data() + produced, want - produced, 0};
-                    const std::size_t res = ZSTD_decompressStream(stream, &outb, &in);
-                    if (ZSTD_isError(res)) {
-                        LOG_ERROR(Crypto, "Solid NCZ: zstd error");
-                        return false;
-                    }
-                    produced += outb.pos;
-                }
-                if (cipher) {
-                    Key128 iv{};
-                    SetIv(iv, s.counter, pos);
-                    cipher->SetIV(iv);
-                    cipher->Transcode(out_buf.data(), produced, out_buf.data(), Op::Encrypt);
-                }
-                data.insert(data.end(), out_buf.begin(), out_buf.begin() + produced);
-                pos += produced;
-                frontier = pos;
-            }
-        }
-        return frontier >= needed;
-    }
-
-    const std::string name;
-    const FileSys::VirtualFile source;
-    const std::vector<Section> sections;
-    const u64 payload_start;
-    mutable std::mutex mutex;
-    mutable std::vector<u8> data;
-    mutable ZSTD_DStream* stream = nullptr;
-    mutable u64 read_pos = 0;
-    mutable u64 frontier = 0;
-    mutable std::vector<u8> in_buf;
-    mutable ZSTD_inBuffer in{nullptr, 0, 0};
-};
-
-// Shared opener: block path always; solid only when allow_solid is true.
-FileSys::VirtualFile OpenNcz(const FileSys::VirtualFile& f, std::string_view name,
-                             bool allow_solid) {
-    if (!f) return nullptr;
-    u64 ps = 0;
-    auto parsed = ParseHeader(f, ps);
-    if (!parsed) return nullptr;
-    auto& [sections, block] = *parsed;
-
-    if (block) {
-        auto hdr = f->ReadBytes(HeaderSize, 0);
-        if (hdr.size() != HeaderSize) return nullptr;
-        std::unique_ptr<BlockReader> body;
-        try { body = std::make_unique<BlockReader>(f, *block, ps); }
-        catch (const std::exception& e) {
-            LOG_ERROR(Crypto, "Failed to open NCZBLOCK: {}", e.what());
-            return nullptr;
-        }
-        return std::make_shared<BlockNczFile>(std::string{name}, std::move(hdr),
-                                              std::move(sections), std::move(body));
-    }
-
-    if (allow_solid) {
-        return std::make_shared<SolidNczFile>(std::string{name}, f, std::move(sections), ps);
-    }
-
-    LOG_DEBUG(Crypto, "Solid NCZ {} skipped (only NCZBLOCK is supported for play)", name);
-    return nullptr;
-}
-
-} // Anonymous namespace
-
-bool IsBlockCompressedNCZ(const FileSys::VirtualFile& f) {
-    if (!f) return false;
-    u64 ps = 0;
-    const auto p = ParseHeader(f, ps);
-    return p && p->second.has_value();
-}
-
-FileSys::VirtualFile DecompressNCZ(const FileSys::VirtualFile& f, std::string_view name) {
-    return OpenNcz(f, name, /*allow_solid=*/false);
-}
-
-FileSys::VirtualFile DecompressNCZForInstall(const FileSys::VirtualFile& f,
-                                             std::string_view name) {
-    return OpenNcz(f, name, /*allow_solid=*/true);
-}
-
-} // namespace Core::Crypto

src/core/crypto/ncz_decompressor.h

@@ -1,35 +0,0 @@
-// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
-// SPDX-License-Identifier: GPL-3.0-or-later
-
-#pragma once
-
-#include <string_view>
-
-#include "core/file_sys/vfs/vfs_types.h"
-
-namespace Core::Crypto {
-
-/**
- * Opens an NCZBLOCK-compressed NCA (nsz -B / .xcz block format) as a VirtualFile backed by
- * on-demand block decoding. Nothing is written to disk; each read decodes only the blocks it
- * covers and re-encrypts CTR sections. Solid NCZ is not supported.
- *
- * @param ncz_file    The raw NCZ payload (e.g. "<id>.ncz" entry from an NSZ/XCZ PFS0).
- * @param output_name Name to give the returned VirtualFile (e.g. "<id>.nca").
- *
- * @return a VirtualFile for the NCA, or nullptr if the NCZ is malformed or not NCZBLOCK.
- */
-[[nodiscard]] FileSys::VirtualFile DecompressNCZ(const FileSys::VirtualFile& ncz_file,
-                                                 std::string_view output_name);
-
-/**
- * Returns true if the given file is an NCZ payload in block-compressed (NCZBLOCK) form,
- * i.e. one that DecompressNCZ() can open. Solid NCZ returns false.
- */
-[[nodiscard]] bool IsBlockCompressedNCZ(const FileSys::VirtualFile& ncz_file);
-
-// Install to NAND: same as DecompressNCZ, but solid NCZ is decoded on demand too.
-[[nodiscard]] FileSys::VirtualFile DecompressNCZForInstall(
-    const FileSys::VirtualFile& ncz_file, std::string_view output_name);
-
-} // namespace Core::Crypto

src/core/file_sys/registered_cache.cpp

@@ -16,7 +16,6 @@
 #include "common/random.h"
 #include "common/string_util.h"
 #include "core/crypto/key_manager.h"
-#include "core/crypto/ncz_decompressor.h"
 #include "core/file_sys/card_image.h"
 #include "core/file_sys/common_funcs.h"
 #include "core/file_sys/content_archive.h"
@@ -159,25 +158,6 @@ static std::shared_ptr<NSP> OpenContainerAsNsp(const VirtualFile& file, Loader::
     return nullptr;
 }
 
-// Checks that every .ncz entry in the container is NCZBLOCK. Solid NCZ has no random access,
-// and the whole point of this build is to reject it at scan time so such files never appear
-// in the game list. Containers without any .ncz (plain NSP/XCI) pass through.
-static bool ContainerIsFullyBlockCompressed(const std::shared_ptr<NSP>& nsp) {
-    if (!nsp) {
-        return false;
-    }
-    for (const auto& entry : nsp->GetFiles()) {
-        const auto name = entry->GetName();
-        if (name.size() < 4 || name.substr(name.size() - 4) != ".ncz") {
-            continue;
-        }
-        if (!Core::Crypto::IsBlockCompressedNCZ(entry)) {
-            return false; // solid NCZ -> reject the whole container
-        }
-    }
-    return true; // no .ncz at all, or all block-compressed
-}
-
 template <typename Callback>
 bool ForEachContainerEntry(const std::shared_ptr<NSP>& nsp, bool only_content,
                            std::optional<u64> base_program_id, Callback&& on_entry) {
@@ -831,14 +811,7 @@ std::vector<ContentProviderEntry> RegisteredCache::ListEntriesFilter(
 }
 
 static std::shared_ptr<NCA> GetNCAFromNSPForID(const NSP& nsp, const NcaID& id) {
-    const auto id_string = Common::HexToString(id, false);
-    auto file = nsp.GetFile(fmt::format("{}.nca", id_string));
-    if (file == nullptr) {
-        if (auto ncz_file = nsp.GetFile(fmt::format("{}.ncz", id_string))) {
-            file = Core::Crypto::DecompressNCZForInstall(
-                ncz_file, fmt::format("{}.nca", id_string));
-        }
-    }
+    auto file = nsp.GetFile(fmt::format("{}.nca", Common::HexToString(id, false)));
     if (file == nullptr) {
         return nullptr;
     }
@@ -1300,12 +1273,6 @@ bool ManualContentProvider::AddEntriesFromContainer(VirtualFile file, bool only_
         return false;
     }
 
-    // Reject solid NCZ (.nsz without -B): only block-compressed NCZ is supported.
-    if (!ContainerIsFullyBlockCompressed(nsp)) {
-        LOG_DEBUG(Service_FS, "Skipping solid-compressed container: {}", file->GetName());
-        return false;
-    }
-
     return ForEachContainerEntry(
         nsp, only_content, base_program_id,
         [this](TitleType title_type, ContentRecordType content_type, u64 title_id,
@@ -1448,9 +1415,8 @@ void ExternalContentProvider::ScanDirectory(const VirtualDir& dir) {
         }
 
         const auto extension = Common::ToLower(filename.substr(dot_pos + 1));
-        // .xcz is an XCI container, but its updates only work through the NSP/PFS0 path
-        // (DecompressNCZ), not ProcessXCI. So route .xcz here on purpose.
-        if (extension == "nsp" || extension == "nsz" || extension == "xcz") {
+
+        if (extension == "nsp") {
             ProcessNSP(file);
         } else if (extension == "xci") {
             ProcessXCI(file);
@@ -1468,12 +1434,6 @@ void ExternalContentProvider::ProcessNSP(const VirtualFile& file) {
         return;
     }
 
-    // Reject solid NCZ (.nsz without -B): Eden only supports block-compressed NCZ.
-    if (!ContainerIsFullyBlockCompressed(nsp)) {
-        LOG_DEBUG(Service_FS, "Skipping solid-compressed container: {}", file->GetName());
-        return;
-    }
-
     LOG_DEBUG(Service_FS, "Processing NSP file: {}", file->GetName());
     AddExternalEntriesFromContainer(nsp, entries, versions, multi_version_entries);
 }

src/core/file_sys/submission_package.cpp

@@ -12,7 +12,6 @@
 #include "common/hex_util.h"
 #include "common/logging.h"
 #include "core/crypto/key_manager.h"
-#include "core/crypto/ncz_decompressor.h"
 #include "core/file_sys/common_funcs.h"
 #include "core/file_sys/content_archive.h"
 #include "core/file_sys/nca_metadata.h"
@@ -247,17 +246,6 @@ void NSP::ReadNCAs(const std::vector<VirtualFile>& files) {
                 const auto id_string = Common::HexToString(rec.nca_id, false);
                 auto next_file = pfs->GetFile(fmt::format("{}.nca", id_string));
 
-                if (next_file == nullptr) {
-                    auto ncz_file = pfs->GetFile(fmt::format("{}.ncz", id_string));
-                    if (ncz_file != nullptr) {
-                        next_file = Core::Crypto::DecompressNCZ(ncz_file, fmt::format("{}.nca", id_string));
-                        if (next_file == nullptr) {
-                            LOG_DEBUG(Service_FS, "Skipping solid or unsupported NCZ content {}.ncz", id_string);
-                            continue;
-                        }
-                    }
-                }
-
                 if (next_file == nullptr) {
                     if (rec.type != ContentRecordType::DeltaFragment) {
                         LOG_WARNING(Service_FS,

src/core/hle/kernel/k_process.cpp

@@ -23,6 +23,9 @@
 #ifdef HAS_NCE
 #include "core/arm/nce/arm_nce.h"
 #endif
+#ifdef HAS_SCARLETNX
+#include "core/arm/scarletnx/scarletnx_process.h"
+#endif
 
 namespace Kernel {
 
@@ -1311,6 +1314,13 @@ void KProcess::InitializeInterfaces(KernelCore& kernel) {
         for (size_t i = 0; i < Core::Hardware::NUM_CPU_CORES; i++)
             m_arm_interfaces[i] = std::make_unique<Core::ArmNce>(kernel.System(), true, i);
     } else
+#endif
+#ifdef HAS_SCARLETNX
+    if (Core::ScarletNxProcess::ShouldUse(kernel.System(), *this)) {
+        auto scarletnx = std::make_shared<Core::ScarletNxProcess>(kernel.System(), *this);
+        for (size_t i = 0; i < Core::Hardware::NUM_CPU_CORES; i++)
+            m_arm_interfaces[i] = Core::MakeScarletNxInterface(scarletnx, this->Is64Bit(), i);
+    } else
 #endif
         if (this->Is64Bit()) {
         for (size_t i = 0; i < Core::Hardware::NUM_CPU_CORES; i++) {

src/core/loader/loader.cpp

@@ -82,27 +82,23 @@ std::shared_ptr<FileSys::NSP> OpenContainerAsNsp(FileSys::VirtualFile file, File
         return nullptr;
     }
 
-    if (type == FileType::NSP || type == FileType::NSZ) {
+    if (type == FileType::NSP) {
         auto nsp = std::make_shared<FileSys::NSP>(file, program_id, program_index);
         return nsp->GetStatus() == ResultStatus::Success ? nsp : nullptr;
     }
 
-    if (type == FileType::XCI || type == FileType::XCZ) {
+    if (type == FileType::XCI) {
         FileSys::XCI xci{file, program_id, program_index};
-        if (xci.GetStatus() == ResultStatus::Success) {
-            auto secure_nsp = xci.GetSecurePartitionNSP();
-            if (secure_nsp != nullptr && secure_nsp->GetStatus() == ResultStatus::Success) {
-                return secure_nsp;
-            }
+        if (xci.GetStatus() != ResultStatus::Success) {
+            return nullptr;
         }
 
-        // PFS0-shaped .xcz (NSZ-style container) does not parse as XCI; fall back to NSP.
-        if (type == FileType::XCZ) {
-            auto nsp = std::make_shared<FileSys::NSP>(file, program_id, program_index);
-            return nsp->GetStatus() == ResultStatus::Success ? nsp : nullptr;
+        auto secure_nsp = xci.GetSecurePartitionNSP();
+        if (secure_nsp == nullptr || secure_nsp->GetStatus() != ResultStatus::Success) {
+            return nullptr;
         }
 
-        return nullptr;
+        return secure_nsp;
     }
 
     return nullptr;
@@ -148,8 +144,7 @@ FileType IdentifyFile(FileSys::VirtualFile file) {
 }
 
 bool IsContainerType(FileType type) {
-    return type == FileType::NSP || type == FileType::NSZ || type == FileType::XCI ||
-           type == FileType::XCZ;
+    return type == FileType::NSP || type == FileType::XCI;
 }
 
 bool IsBootableGameContainer(FileSys::VirtualFile file, FileType type, u64 program_id,
@@ -185,12 +180,8 @@ FileType GuessFromFilename(const std::string& name) {
         return FileType::NCA;
     else if (extension == "xci")
         return FileType::XCI;
-    else if (extension == "xcz")
-        return FileType::XCZ;
     else if (extension == "nsp")
         return FileType::NSP;
-    else if (extension == "nsz")
-        return FileType::NSZ;
     else if (extension == "kip")
         return FileType::KIP;
     return FileType::Unknown;
@@ -206,14 +197,10 @@ std::string GetFileTypeString(FileType type) {
         return "NCA";
     case FileType::XCI:
         return "XCI";
-    case FileType::XCZ:
-        return "XCZ";
     case FileType::NAX:
         return "NAX";
     case FileType::NSP:
         return "NSP";
-    case FileType::NSZ:
-        return "NSZ";
     case FileType::KIP:
         return "KIP";
     case FileType::DeconstructedRomDirectory:
@@ -339,29 +326,12 @@ static std::unique_ptr<AppLoader> GetFileLoader(Core::System& system, FileSys::V
                                                system.GetContentProvider(), program_id,
                                                program_index);
 
-    // NCZ-compressed XCI container. XCI-shaped .xcz goes to the XCI loader, while
-    // PFS0-shaped (NSZ-style) .xcz containers fall back to the NSP loader.
-    case FileType::XCZ: {
-        FileSys::XCI probe{file, program_id, program_index};
-        if (probe.GetStatus() == ResultStatus::Success &&
-            probe.GetSecurePartitionNSP() != nullptr) {
-            return std::make_unique<AppLoader_XCI>(std::move(file),
-                                                   system.GetFileSystemController(),
-                                                   system.GetContentProvider(), program_id,
-                                                   program_index);
-        }
-        return std::make_unique<AppLoader_NSP>(std::move(file), system.GetFileSystemController(),
-                                               system.GetContentProvider(), program_id,
-                                               program_index);
-    }
-
     // NX NAX (NintendoAesXts) file format.
     case FileType::NAX:
         return std::make_unique<AppLoader_NAX>(std::move(file));
 
     // NX NSP (Nintendo Submission Package) file format
     case FileType::NSP:
-    case FileType::NSZ:
         return std::make_unique<AppLoader_NSP>(std::move(file), system.GetFileSystemController(),
                                                system.GetContentProvider(), program_id,
                                                program_index);

src/core/loader/loader.h

@@ -42,9 +42,7 @@ enum class FileType {
     NRO,
     NCA,
     NSP,
-    NSZ,
     XCI,
-    XCZ,
     NAX,
     KIP,
     DeconstructedRomDirectory,

src/core/loader/nsp.cpp

@@ -56,17 +56,6 @@ AppLoader_NSP::AppLoader_NSP(FileSys::VirtualFile file_,
 AppLoader_NSP::~AppLoader_NSP() = default;
 
 FileType AppLoader_NSP::IdentifyType(const FileSys::VirtualFile& nsp_file) {
-    // .nsz is NSP-compatible; return NSZ so the game list shows the right type.
-    if (nsp_file->GetName().ends_with(".nsz")) {
-        return FileType::NSZ;
-    }
-
-    // PFS0-shaped .xcz containers are handled by this loader too; report XCZ so the game
-    // list does not show them as NSP. XCI-shaped .xcz is identified by AppLoader_XCI.
-    if (nsp_file->GetName().ends_with(".xcz")) {
-        return FileType::XCZ;
-    }
-
     const FileSys::NSP nsp(nsp_file);
 
     if (nsp.GetStatus() != ResultStatus::Success) {

src/frontend_common/content_manager.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: 2024 yuzu Emulator Project
@@ -163,9 +163,7 @@ inline InstallResult InstallNSP(Core::System& system, FileSys::VfsFilesystem& vf
 
     std::shared_ptr<FileSys::NSP> nsp;
     FileSys::VirtualFile file = vfs.OpenFile(filename, FileSys::OpenMode::Read);
-    const auto lower_name = boost::to_lower_copy(file->GetName());
-
-    if (lower_name.ends_with("nsp") || lower_name.ends_with("nsz")) {
+    if (boost::to_lower_copy(file->GetName()).ends_with("nsp")) {
         nsp = std::make_shared<FileSys::NSP>(file);
         if (nsp->IsExtractedType()) {
             return InstallResult::Failure;

src/qt_common/config/shared_translation.cpp

@@ -449,7 +449,12 @@ std::unique_ptr<ComboboxTranslationMap> ComboboxEnumeration(QObject* parent) {
     translations->insert({Settings::EnumMetadata<Settings::CpuBackend>::Index(),
                           {
                               PAIR(CpuBackend, Dynarmic, tr("Dynarmic")),
+#ifdef HAS_NCE
                               PAIR(CpuBackend, Nce, tr("NCE")),
+#endif
+#ifdef HAS_SCARLETNX
+                              PAIR(CpuBackend, ScarletNx, tr("ScarletNX")),
+#endif
                           }});
     translations->insert({Settings::EnumMetadata<Settings::FullscreenMode>::Index(),
                           {

src/qt_common/game_list/worker.cpp

@@ -360,8 +360,7 @@ void GameListWorker::ScanFileSystem(ScanTarget target, const std::string& dir_pa
             }
 
             if (target == ScanTarget::PopulateGameList &&
-                (file_type == Loader::FileType::XCI || file_type == Loader::FileType::XCZ ||
-                 file_type == Loader::FileType::NSP || file_type == Loader::FileType::NSZ) &&
+                (file_type == Loader::FileType::XCI || file_type == Loader::FileType::NSP) &&
                 !Loader::IsBootableGameContainer(file, file_type)) {
                 return true;
             }
@@ -376,9 +375,7 @@ void GameListWorker::ScanFileSystem(ScanTarget target, const std::string& dir_pa
                                        program_id, file);
                 } else if (Settings::values.ext_content_from_game_dirs.GetValue() &&
                            (file_type == Loader::FileType::XCI ||
-                            file_type == Loader::FileType::XCZ ||
-                            file_type == Loader::FileType::NSP ||
-                            file_type == Loader::FileType::NSZ)) {
+                            file_type == Loader::FileType::NSP)) {
                     void(provider->AddEntriesFromContainer(file));
                 }
             } else {
@@ -405,8 +402,7 @@ void GameListWorker::ScanFileSystem(ScanTarget target, const std::string& dir_pa
                 };
 
                 if (res2 == Loader::ResultStatus::Success && program_ids.size() > 1 &&
-                    (file_type == Loader::FileType::XCI || file_type == Loader::FileType::XCZ ||
-                     file_type == Loader::FileType::NSP || file_type == Loader::FileType::NSZ)) {
+                    (file_type == Loader::FileType::XCI || file_type == Loader::FileType::NSP)) {
                     for (const auto id : program_ids) {
                         // dravee suggested this, only viable way to
                         // not show sub-games in qlaunch for now.

src/qt_common/qt_common.cpp

@@ -57,8 +57,7 @@ std::unique_ptr<EmuThread> emu_thread = nullptr;
 
 const QStringList supported_file_extensions = {QStringLiteral("nro"), QStringLiteral("nso"),
                                                QStringLiteral("nca"), QStringLiteral("xci"),
-                                               QStringLiteral("xcz"), QStringLiteral("nsp"),
-                                               QStringLiteral("nsz"), QStringLiteral("kip")};
+                                               QStringLiteral("nsp"), QStringLiteral("kip")};
 
 Core::Frontend::WindowSystemType GetWindowSystemType() {
     // Determine WSI type based on Qt platform.

src/yuzu/configuration/configure_cpu.cpp

@@ -34,7 +34,7 @@ ConfigureCpu::ConfigureCpu(const Core::System& system_,
     connect(backend_combobox, qOverload<int>(&QComboBox::currentIndexChanged), this,
             &ConfigureCpu::UpdateGroup);
 
-#ifdef HAS_NCE
+#if defined(HAS_NCE) || defined(HAS_SCARLETNX)
     ui->backend_group->setVisible(true);
 #endif
 }

src/yuzu/main_window.cpp

@@ -2797,9 +2797,9 @@ void MainWindow::IncrementInstallProgress() {
 
 void MainWindow::OnMenuInstallToNAND() {
     const QString file_filter =
-        tr("Installable Switch File (*.nca *.nsp *.nsz *.xci *.xcz);;Nintendo Content Archive "
-           "(*.nca);;Nintendo Submission Package (*.nsp *.nsz);;NX Cartridge "
-           "Image (*.xci *.xcz)");
+        tr("Installable Switch File (*.nca *.nsp *.xci);;Nintendo Content Archive "
+           "(*.nca);;Nintendo Submission Package (*.nsp);;NX Cartridge "
+           "Image (*.xci)");
 
     QStringList filenames = QFileDialog::getOpenFileNames(
         this, tr("Install Files"), QString::fromStdString(UISettings::values.roms_path),
@@ -2856,10 +2856,7 @@ void MainWindow::OnMenuInstallToNAND() {
         QFuture<ContentManager::InstallResult> future;
         ContentManager::InstallResult result;
 
-        if (file.endsWith(QStringLiteral("nsp"), Qt::CaseInsensitive) ||
-            file.endsWith(QStringLiteral("nsz"), Qt::CaseInsensitive) ||
-            file.endsWith(QStringLiteral("xci"), Qt::CaseInsensitive) ||
-            file.endsWith(QStringLiteral("xcz"), Qt::CaseInsensitive)) {
+        if (file.endsWith(QStringLiteral("nsp"), Qt::CaseInsensitive)) {
             const auto progress_callback = [this](size_t size, size_t progress) {
                 emit UpdateInstallProgress();
                 if (install_progress->wasCanceled()) {
@@ -3664,12 +3661,12 @@ void MainWindow::OnToggleGraphicsAPI() {
         api = Settings::RendererBackend::OpenGL_GLSL;
         break;
     case Settings::RendererBackend::OpenGL_GLSL:
-        api = Settings::RendererBackend::OpenGL_GLSL;
-        break;
-    case Settings::RendererBackend::OpenGL_SPIRV:
         api = Settings::RendererBackend::OpenGL_GLASM;
         break;
     case Settings::RendererBackend::OpenGL_GLASM:
+        api = Settings::RendererBackend::OpenGL_SPIRV;
+        break;
+    case Settings::RendererBackend::OpenGL_SPIRV:
         api = Settings::RendererBackend::Null;
         break;
 #else