Merge branch 'gdb-stub' into 'master'

Add GDB Stub

See merge request [ryubing/ryujinx!71](https://git.ryujinx.app/ryubing/ryujinx/-/merge_requests/71)

assets/locales.json

@@ -25021,6 +25021,181 @@
         "zh_CN": "动态 Rich Presence",
         "zh_TW": "動態 Rich Presence"
       }
+    },
+    {
+      "ID": "SettingsTabDebug",
+      "Translations": {
+        "ar_SA": "",
+        "de_DE": "",
+        "el_GR": "",
+        "en_US": "Debug",
+        "es_ES": "",
+        "fr_FR": "",
+        "he_IL": "",
+        "it_IT": "",
+        "ja_JP": "",
+        "ko_KR": "",
+        "no_NO": "",
+        "pl_PL": "",
+        "pt_BR": "",
+        "ru_RU": "",
+        "sv_SE": "",
+        "th_TH": "",
+        "tr_TR": "",
+        "uk_UA": "",
+        "zh_CN": "",
+        "zh_TW": ""
+      }
+    },
+    {
+      "ID": "SettingsTabDebugTitle",
+      "Translations": {
+        "ar_SA": "",
+        "de_DE": "",
+        "el_GR": "",
+        "en_US": "Debug (WARNING: For developer use only)",
+        "es_ES": "",
+        "fr_FR": "",
+        "he_IL": "",
+        "it_IT": "",
+        "ja_JP": "",
+        "ko_KR": "",
+        "no_NO": "",
+        "pl_PL": "",
+        "pt_BR": "",
+        "ru_RU": "",
+        "sv_SE": "",
+        "th_TH": "",
+        "tr_TR": "",
+        "uk_UA": "",
+        "zh_CN": "",
+        "zh_TW": ""
+      }
+    },
+    {
+      "ID": "EnableGDBStub",
+      "Translations": {
+        "ar_SA": "",
+        "de_DE": "",
+        "el_GR": "",
+        "en_US": "Enable GDB Stub",
+        "es_ES": "",
+        "fr_FR": "",
+        "he_IL": "",
+        "it_IT": "",
+        "ja_JP": "",
+        "ko_KR": "",
+        "no_NO": "",
+        "pl_PL": "",
+        "pt_BR": "",
+        "ru_RU": "",
+        "sv_SE": "",
+        "th_TH": "",
+        "tr_TR": "",
+        "uk_UA": "",
+        "zh_CN": "",
+        "zh_TW": ""
+      }
+    },
+    {
+      "ID": "GDBStubToggleTooltip",
+      "Translations": {
+        "ar_SA": "",
+        "de_DE": "",
+        "el_GR": "",
+        "en_US": "Enables the GDB stub which makes it possible to debug the running application. For development use only!",
+        "es_ES": "",
+        "fr_FR": "",
+        "he_IL": "",
+        "it_IT": "",
+        "ja_JP": "",
+        "ko_KR": "",
+        "no_NO": "",
+        "pl_PL": "",
+        "pt_BR": "",
+        "ru_RU": "",
+        "sv_SE": "",
+        "th_TH": "",
+        "tr_TR": "",
+        "uk_UA": "",
+        "zh_CN": "",
+        "zh_TW": ""
+      }
+    },
+    {
+      "ID": "GDBStubPort",
+      "Translations": {
+        "ar_SA": "",
+        "de_DE": "",
+        "el_GR": "",
+        "en_US": "GDB stub port:",
+        "es_ES": "",
+        "fr_FR": "",
+        "he_IL": "",
+        "it_IT": "",
+        "ja_JP": "",
+        "ko_KR": "",
+        "no_NO": "",
+        "pl_PL": "",
+        "pt_BR": "",
+        "ru_RU": "",
+        "sv_SE": "",
+        "th_TH": "",
+        "tr_TR": "",
+        "uk_UA": "",
+        "zh_CN": "",
+        "zh_TW": ""
+      }
+    },
+    {
+      "ID": "DebuggerSuspendOnStart",
+      "Translations": {
+        "ar_SA": "",
+        "de_DE": "",
+        "el_GR": "",
+        "en_US": "Suspend application on start",
+        "es_ES": "",
+        "fr_FR": "",
+        "he_IL": "",
+        "it_IT": "",
+        "ja_JP": "",
+        "ko_KR": "",
+        "no_NO": "",
+        "pl_PL": "",
+        "pt_BR": "",
+        "ru_RU": "",
+        "sv_SE": "",
+        "th_TH": "",
+        "tr_TR": "",
+        "uk_UA": "",
+        "zh_CN": "",
+        "zh_TW": ""
+      }
+    },
+    {
+      "ID": "DebuggerSuspendOnStartTooltip",
+      "Translations": {
+        "ar_SA": "",
+        "de_DE": "",
+        "el_GR": "",
+        "en_US": "Suspends the application before executing the first instruction, allowing for debugging from the earliest point.",
+        "es_ES": "",
+        "fr_FR": "",
+        "he_IL": "",
+        "it_IT": "",
+        "ja_JP": "",
+        "ko_KR": "",
+        "no_NO": "",
+        "pl_PL": "",
+        "pt_BR": "",
+        "ru_RU": "",
+        "sv_SE": "",
+        "th_TH": "",
+        "tr_TR": "",
+        "uk_UA": "",
+        "zh_CN": "",
+        "zh_TW": ""
+      }
     }
   ]
 }

src/ARMeilleure/Instructions/NativeInterface.cs

@@ -3,6 +3,8 @@ using ARMeilleure.State;
 using ARMeilleure.Translation;
 using System;
 using System.Runtime.InteropServices;
+using System.Threading;
+using ExecutionContext = ARMeilleure.State.ExecutionContext;
 
 namespace ARMeilleure.Instructions
 {
@@ -200,7 +202,11 @@ namespace ARMeilleure.Instructions
 
             ExecutionContext context = GetContext();
 
-            context.CheckInterrupt();
+            // If debugging, we'll handle interrupts outside
+            if (!Optimizations.EnableDebugging)
+            {
+                context.CheckInterrupt();
+            }
 
             Statistics.ResumeTimer();
 

src/ARMeilleure/Optimizations.cs

@@ -12,6 +12,7 @@ namespace ARMeilleure
 
         public static bool AllowLcqInFunctionTable { get; set; } = true;
         public static bool UseUnmanagedDispatchLoop { get; set; } = true;
+        public static bool EnableDebugging { get; set; } = false;
 
         public static bool UseAdvSimdIfAvailable { get; set; } = true;
         public static bool UseArm64AesIfAvailable { get; set; } = true;

src/ARMeilleure/State/ExecutionContext.cs

@@ -1,4 +1,7 @@
 using ARMeilleure.Memory;
+using System.Collections.Concurrent;
+using System.Diagnostics;
+using System.Threading;
 
 namespace ARMeilleure.State
 {
@@ -10,7 +13,7 @@ namespace ARMeilleure.State
 
         internal nint NativeContextPtr => _nativeContext.BasePtr;
 
-        private bool _interrupted;
+        internal bool Interrupted { get; private set; }
 
         private readonly ICounter _counter;
 
@@ -65,6 +68,8 @@ namespace ARMeilleure.State
 
         public bool IsAarch32 { get; set; }
 
+        public ulong ThreadUid { get; set; }
+
         internal ExecutionMode ExecutionMode
         {
             get
@@ -90,14 +95,19 @@ namespace ARMeilleure.State
 
         private readonly ExceptionCallbackNoArgs _interruptCallback;
         private readonly ExceptionCallback _breakCallback;
+        private readonly ExceptionCallbackNoArgs _stepCallback;
         private readonly ExceptionCallback _supervisorCallback;
         private readonly ExceptionCallback _undefinedCallback;
 
+        internal int ShouldStep;
+        public ulong DebugPc { get; set; }
+
         public ExecutionContext(
             IJitMemoryAllocator allocator,
             ICounter counter,
             ExceptionCallbackNoArgs interruptCallback = null,
             ExceptionCallback breakCallback = null,
+            ExceptionCallbackNoArgs stepCallback = null,
             ExceptionCallback supervisorCallback = null,
             ExceptionCallback undefinedCallback = null)
         {
@@ -105,6 +115,7 @@ namespace ARMeilleure.State
             _counter = counter;
             _interruptCallback = interruptCallback;
             _breakCallback = breakCallback;
+            _stepCallback = stepCallback;
             _supervisorCallback = supervisorCallback;
             _undefinedCallback = undefinedCallback;
 
@@ -127,9 +138,9 @@ namespace ARMeilleure.State
 
         internal void CheckInterrupt()
         {
-            if (_interrupted)
+            if (Interrupted)
             {
-                _interrupted = false;
+                Interrupted = false;
 
                 _interruptCallback?.Invoke(this);
             }
@@ -139,7 +150,18 @@ namespace ARMeilleure.State
 
         public void RequestInterrupt()
         {
-            _interrupted = true;
+            Interrupted = true;
+        }
+
+        public void StepHandler()
+        {
+            _stepCallback.Invoke(this);
+        }
+
+        public void RequestDebugStep()
+        {
+            Interlocked.Exchange(ref ShouldStep, 1);
+            RequestInterrupt();
         }
 
         internal void OnBreak(ulong address, int imm)

src/ARMeilleure/Translation/Translator.cs

@@ -119,7 +119,25 @@ namespace ARMeilleure.Translation
 
             NativeInterface.RegisterThread(context, Memory, this);
 
-            if (Optimizations.UseUnmanagedDispatchLoop)
+            if (Optimizations.EnableDebugging)
+            {
+                context.DebugPc = address;
+                do
+                {
+                    if (Interlocked.CompareExchange(ref context.ShouldStep, 0, 1) == 1)
+                    {
+                        context.DebugPc = Step(context, context.DebugPc);
+                        context.StepHandler();
+                    }
+                    else
+                    {
+                        context.DebugPc = ExecuteSingle(context, context.DebugPc);
+                    }
+                    context.CheckInterrupt();
+                }
+                while (context.Running && context.DebugPc != 0);
+            }
+            else if (Optimizations.UseUnmanagedDispatchLoop)
             {
                 Stubs.DispatchLoop(context.NativeContextPtr, address);
             }
@@ -175,7 +193,7 @@ namespace ARMeilleure.Translation
             return nextAddr;
         }
 
-        public ulong Step(State.ExecutionContext context, ulong address)
+        private ulong Step(State.ExecutionContext context, ulong address)
         {
             TranslatedFunction func = Translate(address, context.ExecutionMode, highCq: false, singleStep: true);
 
@@ -228,7 +246,7 @@ namespace ARMeilleure.Translation
                 Stubs,
                 address,
                 highCq,
-                _ptc.State != PtcState.Disabled,
+                _ptc.State != PtcState.Disabled && !Optimizations.EnableDebugging,
                 mode: Aarch32Mode.User);
 
             Logger.StartPass(PassName.Decoding);
@@ -367,9 +385,8 @@ namespace ARMeilleure.Translation
 
                 if (block.Exit)
                 {
-                    // Left option here as it may be useful if we need to return to managed rather than tail call in
+                    // Return to managed rather than tail call.
-                    // future. (eg. for debug)
+                    bool useReturns = Optimizations.EnableDebugging;
-                    bool useReturns = false;
 
                     InstEmitFlowHelper.EmitVirtualJump(context, Const(block.Address), isReturn: useReturns);
                 }

src/Ryujinx.Common/Logging/LogClass.cs

@@ -13,6 +13,7 @@ namespace Ryujinx.Common.Logging
         Cpu,
         Emulation,
         FFmpeg,
+        GdbStub,
         Font,
         Gpu,
         Hid,

src/Ryujinx.Cpu/AppleHv/Arm/ExceptionLevel.cs

@@ -0,0 +1,10 @@
+namespace Ryujinx.Cpu.AppleHv.Arm
+{
+    enum ExceptionLevel : uint
+    {
+        PstateMask = 0xfffffff0,
+        EL1h = 0b0101,
+        El1t = 0b0100,
+        EL0 = 0b0000,
+    }
+}

src/Ryujinx.Cpu/AppleHv/HvExecutionContext.cs

@@ -11,7 +11,18 @@ namespace Ryujinx.Cpu.AppleHv
     class HvExecutionContext : IExecutionContext
     {
         /// <inheritdoc/>
-        public ulong Pc => _impl.ElrEl1;
+        public ulong Pc
+        {
+            get
+            {
+                uint currentEl = Pstate & ~((uint)ExceptionLevel.PstateMask);
+                if (currentEl == (uint)ExceptionLevel.EL1h)
+                {
+                    return _impl.ElrEl1;
+                }
+                return _impl.Pc;
+            }
+        }
 
         /// <inheritdoc/>
         public long TpidrEl0
@@ -48,6 +59,9 @@ namespace Ryujinx.Cpu.AppleHv
             set => _impl.Fpsr = value;
         }
 
+        /// <inheritdoc/>
+        public ulong ThreadUid { get; set; }
+
         /// <inheritdoc/>
         public bool IsAarch32
         {
@@ -67,6 +81,7 @@ namespace Ryujinx.Cpu.AppleHv
         private readonly ICounter _counter;
         private readonly IHvExecutionContext _shadowContext;
         private IHvExecutionContext _impl;
+        private int _shouldStep;
 
         private readonly ExceptionCallbacks _exceptionCallbacks;
 
@@ -103,6 +118,11 @@ namespace Ryujinx.Cpu.AppleHv
             _exceptionCallbacks.BreakCallback?.Invoke(this, address, imm);
         }
 
+        private void StepHandler()
+        {
+            _exceptionCallbacks.StepCallback?.Invoke(this);
+        }
+
         private void SupervisorCallHandler(ulong address, int imm)
         {
             _exceptionCallbacks.SupervisorCallback?.Invoke(this, address, imm);
@@ -127,6 +147,30 @@ namespace Ryujinx.Cpu.AppleHv
             return Interlocked.Exchange(ref _interruptRequested, 0) != 0;
         }
 
+        /// <inheritdoc/>
+        public void RequestDebugStep()
+        {
+            Interlocked.Exchange(ref _shouldStep, 1);
+        }
+
+        /// <inheritdoc/>
+        public ulong DebugPc
+        {
+            get => Pc;
+            set
+            {
+                uint currentEl = Pstate & ~((uint)ExceptionLevel.PstateMask);
+                if (currentEl == (uint)ExceptionLevel.EL1h)
+                {
+                    _impl.ElrEl1 = value;
+                }
+                else
+                {
+                    _impl.Pc = value;
+                }
+            }
+        }
+
         /// <inheritdoc/>
         public void StopRunning()
         {
@@ -142,6 +186,22 @@ namespace Ryujinx.Cpu.AppleHv
 
             while (Running)
             {
+                if (Interlocked.CompareExchange(ref _shouldStep, 0, 1) == 1)
+                {
+                    uint currentEl = Pstate & ~((uint)ExceptionLevel.PstateMask);
+                    if (currentEl == (uint)ExceptionLevel.EL1h)
+                    {
+                        HvApi.hv_vcpu_get_sys_reg(vcpu.Handle, HvSysReg.SPSR_EL1, out ulong spsr).ThrowOnError();
+                        spsr |= (1 << 21);
+                        HvApi.hv_vcpu_set_sys_reg(vcpu.Handle, HvSysReg.SPSR_EL1, spsr);
+                    }
+                    else
+                    {
+                        Pstate |= (1 << 21);
+                    }
+                    HvApi.hv_vcpu_set_sys_reg(vcpu.Handle, HvSysReg.MDSCR_EL1, 1);
+                }
+
                 HvApi.hv_vcpu_run(vcpu.Handle).ThrowOnError();
 
                 HvExitReason reason = vcpu.ExitInfo->Reason;
@@ -209,6 +269,20 @@ namespace Ryujinx.Cpu.AppleHv
                     SupervisorCallHandler(elr - 4UL, id);
                     vcpu = RentFromPool(memoryManager.AddressSpace, vcpu);
                     break;
+                case ExceptionClass.SoftwareStepLowerEl:
+                    HvApi.hv_vcpu_get_sys_reg(vcpuHandle, HvSysReg.SPSR_EL1, out ulong spsr).ThrowOnError();
+                    spsr &= ~((ulong)(1 << 21));
+                    HvApi.hv_vcpu_set_sys_reg(vcpuHandle, HvSysReg.SPSR_EL1, spsr).ThrowOnError();
+                    HvApi.hv_vcpu_set_sys_reg(vcpuHandle, HvSysReg.MDSCR_EL1, 0);
+                    ReturnToPool(vcpu);
+                    StepHandler();
+                    vcpu = RentFromPool(memoryManager.AddressSpace, vcpu);
+                    break;
+                case ExceptionClass.BrkAarch64:
+                    ReturnToPool(vcpu);
+                    BreakHandler(elr, (ushort)esr);
+                    vcpu = RentFromPool(memoryManager.AddressSpace, vcpu);
+                    break;
                 default:
                     throw new Exception($"Unhandled guest exception {ec}.");
             }
@@ -219,10 +293,7 @@ namespace Ryujinx.Cpu.AppleHv
                 // TODO: Invalidate only the range that was modified?
                 return HvAddressSpace.KernelRegionTlbiEretAddress;
             }
-            else
+            return HvAddressSpace.KernelRegionEretAddress;
-            {
-                return HvAddressSpace.KernelRegionEretAddress;
-            }
         }
 
         private static void DataAbort(MemoryTracking tracking, ulong vcpu, uint esr)

src/Ryujinx.Cpu/AppleHv/HvExecutionContextShadow.cs

@@ -18,6 +18,8 @@ namespace Ryujinx.Cpu.AppleHv
 
         public bool IsAarch32 { get; set; }
 
+        public ulong ThreadUid { get; set; }
+
         private readonly ulong[] _x;
         private readonly V128[] _v;
 
@@ -46,5 +48,14 @@ namespace Ryujinx.Cpu.AppleHv
         {
             _v[index] = value;
         }
+
+        public void RequestInterrupt()
+        {
+        }
+
+        public bool GetAndClearInterruptRequested()
+        {
+            return false;
+        }
     }
 }

src/Ryujinx.Cpu/AppleHv/HvExecutionContextVcpu.cs

@@ -2,6 +2,7 @@ using ARMeilleure.State;
 using Ryujinx.Memory;
 using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
+using System.Threading;
 
 namespace Ryujinx.Cpu.AppleHv
 {
@@ -13,6 +14,8 @@ namespace Ryujinx.Cpu.AppleHv
         private static readonly SetSimdFpReg _setSimdFpReg;
         private static readonly nint _setSimdFpRegNativePtr;
 
+        public ulong ThreadUid { get; set; }
+
         static HvExecutionContextVcpu()
         {
             // .NET does not support passing vectors by value, so we need to pass a pointer and use a native
@@ -135,6 +138,7 @@ namespace Ryujinx.Cpu.AppleHv
         }
 
         private readonly ulong _vcpu;
+        private int _interruptRequested;
 
         public HvExecutionContextVcpu(ulong vcpu)
         {
@@ -180,8 +184,16 @@ namespace Ryujinx.Cpu.AppleHv
 
         public void RequestInterrupt()
         {
-            ulong vcpu = _vcpu;
+            if (Interlocked.Exchange(ref _interruptRequested, 1) == 0)
-            HvApi.hv_vcpus_exit(ref vcpu, 1);
+            {
+                ulong vcpu = _vcpu;
+                HvApi.hv_vcpus_exit(ref vcpu, 1);
+            }
+        }
+
+        public bool GetAndClearInterruptRequested()
+        {
+            return Interlocked.Exchange(ref _interruptRequested, 0) != 0;
         }
     }
 }

src/Ryujinx.Cpu/AppleHv/IHvExecutionContext.cs

@@ -15,6 +15,7 @@ namespace Ryujinx.Cpu.AppleHv
 
         uint Fpcr { get; set; }
         uint Fpsr { get; set; }
+        ulong ThreadUid { get; set; }
 
         ulong GetX(int index);
         void SetX(int index, ulong value);
@@ -39,5 +40,8 @@ namespace Ryujinx.Cpu.AppleHv
                 SetV(i, context.GetV(i));
             }
         }
+
+        void RequestInterrupt();
+        bool GetAndClearInterruptRequested();
     }
 }

src/Ryujinx.Cpu/ExceptionCallbacks.cs

@@ -29,6 +29,11 @@ namespace Ryujinx.Cpu
         /// </summary>
         public readonly ExceptionCallback BreakCallback;
 
+        /// <summary>
+        /// Handler for CPU software interrupts caused by single-stepping.
+        /// </summary>
+        public readonly ExceptionCallbackNoArgs StepCallback;
+
         /// <summary>
         /// Handler for CPU software interrupts caused by the Arm SVC instruction.
         /// </summary>
@@ -47,16 +52,19 @@ namespace Ryujinx.Cpu
         /// </remarks>
         /// <param name="interruptCallback">Handler for CPU interrupts triggered using <see cref="IExecutionContext.RequestInterrupt"/></param>
         /// <param name="breakCallback">Handler for CPU software interrupts caused by the Arm BRK instruction</param>
+        /// <param name="stepCallback">Handler for CPU software interrupts caused by single-stepping</param>
         /// <param name="supervisorCallback">Handler for CPU software interrupts caused by the Arm SVC instruction</param>
         /// <param name="undefinedCallback">Handler for CPU software interrupts caused by any undefined Arm instruction</param>
         public ExceptionCallbacks(
             ExceptionCallbackNoArgs interruptCallback = null,
             ExceptionCallback breakCallback = null,
+            ExceptionCallbackNoArgs stepCallback = null,
             ExceptionCallback supervisorCallback = null,
             ExceptionCallback undefinedCallback = null)
         {
             InterruptCallback = interruptCallback;
             BreakCallback = breakCallback;
+            StepCallback = stepCallback;
             SupervisorCallback = supervisorCallback;
             UndefinedCallback = undefinedCallback;
         }

src/Ryujinx.Cpu/IExecutionContext.cs

@@ -1,5 +1,6 @@
 using ARMeilleure.State;
 using System;
+using System.Threading;
 
 namespace Ryujinx.Cpu
 {
@@ -46,6 +47,11 @@ namespace Ryujinx.Cpu
         /// </summary>
         bool IsAarch32 { get; set; }
 
+        /// <summary>
+        /// Thread UID.
+        /// </summary>
+        public ulong ThreadUid { get; set; }
+
         /// <summary>
         /// Indicates whenever the CPU is still running code.
         /// </summary>
@@ -108,5 +114,23 @@ namespace Ryujinx.Cpu
         /// If you only need to pause the thread temporarily, use <see cref="RequestInterrupt"/> instead.
         /// </remarks>
         void StopRunning();
+
+        /// <summary>
+        /// Requests the thread to stop running temporarily and call <see cref="ExceptionCallbacks.InterruptCallback"/>.
+        /// </summary>
+        /// <remarks>
+        /// The thread might not pause immediately.
+        /// One must not assume that guest code is no longer being executed by the thread after calling this function.
+        /// After single stepping, the thread should call call <see cref="ExceptionCallbacks.StepCallback"/>.
+        /// </remarks>
+        void RequestDebugStep();
+
+        /// <summary>
+        /// Current Program Counter (for debugging).
+        /// </summary>
+        /// <remarks>
+        /// PC register for the debugger. Must not be accessed while the thread isn't stopped for debugging.
+        /// </remarks>
+        ulong DebugPc { get; set; }
     }
 }

src/Ryujinx.Cpu/Jit/JitExecutionContext.cs

@@ -1,5 +1,7 @@
 using ARMeilleure.Memory;
 using ARMeilleure.State;
+using System.Threading;
+using ExecutionContext = ARMeilleure.State.ExecutionContext;
 
 namespace Ryujinx.Cpu.Jit
 {
@@ -53,6 +55,13 @@ namespace Ryujinx.Cpu.Jit
             set => _impl.IsAarch32 = value;
         }
 
+        /// <inheritdoc/>
+        public ulong ThreadUid
+        {
+            get => _impl.ThreadUid;
+            set => _impl.ThreadUid = value;
+        }
+
         /// <inheritdoc/>
         public bool Running => _impl.Running;
 
@@ -65,6 +74,7 @@ namespace Ryujinx.Cpu.Jit
                 counter,
                 InterruptHandler,
                 BreakHandler,
+                StepHandler,
                 SupervisorCallHandler,
                 UndefinedHandler);
 
@@ -93,6 +103,11 @@ namespace Ryujinx.Cpu.Jit
             _exceptionCallbacks.BreakCallback?.Invoke(this, address, imm);
         }
 
+        private void StepHandler(ExecutionContext context)
+        {
+            _exceptionCallbacks.StepCallback?.Invoke(this);
+        }
+
         private void SupervisorCallHandler(ExecutionContext context, ulong address, int imm)
         {
             _exceptionCallbacks.SupervisorCallback?.Invoke(this, address, imm);
@@ -109,6 +124,16 @@ namespace Ryujinx.Cpu.Jit
             _impl.RequestInterrupt();
         }
 
+        /// <inheritdoc/>
+        public void RequestDebugStep() => _impl.RequestDebugStep();
+
+        /// <inheritdoc/>
+        public ulong DebugPc
+        {
+            get => _impl.DebugPc;
+            set => _impl.DebugPc = value;
+        }
+
         /// <inheritdoc/>
         public void StopRunning()
         {

src/Ryujinx.Cpu/LightningJit/State/ExecutionContext.cs

@@ -1,6 +1,7 @@
 using ARMeilleure.Memory;
 using ARMeilleure.State;
 using System;
+using System.Threading;
 
 namespace Ryujinx.Cpu.LightningJit.State
 {
@@ -51,6 +52,8 @@ namespace Ryujinx.Cpu.LightningJit.State
         }
 
         public bool IsAarch32 { get; set; }
+        
+        public ulong ThreadUid { get; set; }
 
         internal ExecutionMode ExecutionMode
         {
@@ -77,15 +80,20 @@ namespace Ryujinx.Cpu.LightningJit.State
 
         private readonly ExceptionCallbackNoArgs _interruptCallback;
         private readonly ExceptionCallback _breakCallback;
+        private readonly ExceptionCallbackNoArgs _stepCallback;
         private readonly ExceptionCallback _supervisorCallback;
         private readonly ExceptionCallback _undefinedCallback;
 
+        internal int ShouldStep;
+        public ulong DebugPc { get; set; }
+
         public ExecutionContext(IJitMemoryAllocator allocator, ICounter counter, ExceptionCallbacks exceptionCallbacks)
         {
             _nativeContext = new NativeContext(allocator);
             _counter = counter;
             _interruptCallback = exceptionCallbacks.InterruptCallback;
             _breakCallback = exceptionCallbacks.BreakCallback;
+            _stepCallback = exceptionCallbacks.StepCallback;
             _supervisorCallback = exceptionCallbacks.SupervisorCallback;
             _undefinedCallback = exceptionCallbacks.UndefinedCallback;
 
@@ -117,6 +125,17 @@ namespace Ryujinx.Cpu.LightningJit.State
             _interrupted = true;
         }
 
+        public void StepHandler()
+        {
+            _stepCallback.Invoke(this);
+        }
+
+        public void RequestDebugStep()
+        {
+            Interlocked.Exchange(ref ShouldStep, 1);
+            RequestInterrupt();
+        }
+
         internal void OnBreak(ulong address, int imm)
         {
             _breakCallback?.Invoke(this, address, imm);

src/Ryujinx.HLE/Debugger/DebugState.cs

@@ -0,0 +1,9 @@
+namespace Ryujinx.HLE.Debugger
+{
+    public enum DebugState
+    {
+        Running,
+        Stopping,
+        Stopped,
+    }
+}

src/Ryujinx.HLE/Debugger/Debugger.cs

@@ -0,0 +1,906 @@
+using ARMeilleure.State;
+using Ryujinx.Common;
+using Ryujinx.Common.Logging;
+using Ryujinx.HLE.HOS.Kernel;
+using Ryujinx.HLE.HOS.Kernel.Threading;
+using Ryujinx.Memory;
+using System;
+using System.Collections.Concurrent;
+using System.IO;
+using System.Linq;
+using System.Net;
+using System.Net.Sockets;
+using System.Text;
+using System.Threading;
+using IExecutionContext = Ryujinx.Cpu.IExecutionContext;
+
+namespace Ryujinx.HLE.Debugger
+{
+    public class Debugger : IDisposable
+    {
+        internal Switch Device { get; private set; }
+
+        public ushort GdbStubPort { get; private set; }
+
+        private TcpListener ListenerSocket;
+        private Socket ClientSocket = null;
+        private NetworkStream ReadStream = null;
+        private NetworkStream WriteStream = null;
+        private BlockingCollection<IMessage> Messages = new BlockingCollection<IMessage>(1);
+        private Thread DebuggerThread;
+        private Thread MessageHandlerThread;
+        private bool _shuttingDown = false;
+
+        private ulong? cThread;
+        private ulong? gThread;
+
+        public Debugger(Switch device, ushort port)
+        {
+            Device = device;
+            GdbStubPort = port;
+
+            ARMeilleure.Optimizations.EnableDebugging = true;
+
+            DebuggerThread = new Thread(DebuggerThreadMain);
+            DebuggerThread.Start();
+            MessageHandlerThread = new Thread(MessageHandlerMain);
+            MessageHandlerThread.Start();
+        }
+
+        private IDebuggableProcess DebugProcess => Device.System.DebugGetApplicationProcess();
+        private KThread[] GetThreads() => DebugProcess.GetThreadUids().Select(x => DebugProcess.GetThread(x)).ToArray();
+        private bool IsProcessAarch32 => DebugProcess.GetThread(gThread.Value).Context.IsAarch32;
+        private KernelContext KernelContext => Device.System.KernelContext;
+
+        const int GdbRegisterCount64 = 68;
+        const int GdbRegisterCount32 = 66;
+        /* FPCR = FPSR & ~FpcrMask
+        All of FPCR's bits are reserved in FPCR and vice versa,
+        see ARM's documentation. */
+        private const uint FpcrMask = 0xfc1fffff;
+
+        private string GdbReadRegister64(IExecutionContext state, int gdbRegId)
+        {
+            switch (gdbRegId)
+            {
+                case >= 0 and <= 31:
+                    return ToHex(BitConverter.GetBytes(state.GetX(gdbRegId)));
+                case 32:
+                    return ToHex(BitConverter.GetBytes(state.DebugPc));
+                case 33:
+                    return ToHex(BitConverter.GetBytes(state.Pstate));
+                case >= 34 and <= 65:
+                    return ToHex(state.GetV(gdbRegId - 34).ToArray());
+                case 66:
+                    return ToHex(BitConverter.GetBytes((uint)state.Fpsr));
+                case 67:
+                    return ToHex(BitConverter.GetBytes((uint)state.Fpcr));
+                default:
+                    return null;
+            }
+        }
+
+        private bool GdbWriteRegister64(IExecutionContext state, int gdbRegId, StringStream ss)
+        {
+            switch (gdbRegId)
+            {
+                case >= 0 and <= 31:
+                    {
+                        ulong value = ss.ReadLengthAsHex(16);
+                        state.SetX(gdbRegId, value);
+                        return true;
+                    }
+                case 32:
+                    {
+                        ulong value = ss.ReadLengthAsHex(16);
+                        state.DebugPc = value;
+                        return true;
+                    }
+                case 33:
+                    {
+                        ulong value = ss.ReadLengthAsHex(8);
+                        state.Pstate = (uint)value;
+                        return true;
+                    }
+                case >= 34 and <= 65:
+                    {
+                        ulong value0 = ss.ReadLengthAsHex(16);
+                        ulong value1 = ss.ReadLengthAsHex(16);
+                        state.SetV(gdbRegId - 34, new V128(value0, value1));
+                        return true;
+                    }
+                case 66:
+                    {
+                        ulong value = ss.ReadLengthAsHex(8);
+                        state.Fpsr = (uint)value;
+                        return true;
+                    }
+                case 67:
+                    {
+                        ulong value = ss.ReadLengthAsHex(8);
+                        state.Fpcr = (uint)value;
+                        return true;
+                    }
+                default:
+                    return false;
+            }
+        }
+
+        private string GdbReadRegister32(IExecutionContext state, int gdbRegId)
+        {
+            switch (gdbRegId)
+            {
+                case >= 0 and <= 14:
+                    return ToHex(BitConverter.GetBytes((uint)state.GetX(gdbRegId)));
+                case 15:
+                    return ToHex(BitConverter.GetBytes((uint)state.DebugPc));
+                case 16:
+                    return ToHex(BitConverter.GetBytes((uint)state.Pstate));
+                case >= 17 and <= 32:
+                    return ToHex(state.GetV(gdbRegId - 17).ToArray());
+                case >= 33 and <= 64:
+                    int reg = (gdbRegId - 33);
+                    int n = reg / 2;
+                    int shift = reg % 2;
+                    ulong value = state.GetV(n).Extract<ulong>(shift);
+                    return ToHex(BitConverter.GetBytes(value));
+                case 65:
+                    uint fpscr = (uint)state.Fpsr | (uint)state.Fpcr;
+                    return ToHex(BitConverter.GetBytes(fpscr));
+                default:
+                    return null;
+            }
+        }
+
+        private bool GdbWriteRegister32(IExecutionContext state, int gdbRegId, StringStream ss)
+        {
+            switch (gdbRegId)
+            {
+                case >= 0 and <= 14:
+                    {
+                        ulong value = ss.ReadLengthAsHex(8);
+                        state.SetX(gdbRegId, value);
+                        return true;
+                    }
+                case 15:
+                    {
+                        ulong value = ss.ReadLengthAsHex(8);
+                        state.DebugPc = value;
+                        return true;
+                    }
+                case 16:
+                    {
+                        ulong value = ss.ReadLengthAsHex(8);
+                        state.Pstate = (uint)value;
+                        return true;
+                    }
+                case >= 17 and <= 32:
+                    {
+                        ulong value0 = ss.ReadLengthAsHex(16);
+                        ulong value1 = ss.ReadLengthAsHex(16);
+                        state.SetV(gdbRegId - 17, new V128(value0, value1));
+                        return true;
+                    }
+                case >= 33 and <= 64:
+                    {
+                        ulong value = ss.ReadLengthAsHex(16);
+                        int regId = (gdbRegId - 33);
+                        int regNum = regId / 2;
+                        int shift = regId % 2;
+                        V128 reg = state.GetV(regNum);
+                        reg.Insert(shift, value);
+                        return true;
+                    }
+                case 65:
+                    {
+                        ulong value = ss.ReadLengthAsHex(8);
+                        state.Fpsr = (uint)value & FpcrMask;
+                        state.Fpcr = (uint)value & ~FpcrMask;
+                        return true;
+                    }
+                default:
+                    return false;
+            }
+        }
+
+        private void MessageHandlerMain()
+        {
+            while (!_shuttingDown)
+            {
+                IMessage msg = Messages.Take();
+                switch (msg)
+                {
+                    case BreakInMessage:
+                        Logger.Notice.Print(LogClass.GdbStub, "Break-in requested");
+                        CommandQuery();
+                        break;
+
+                    case SendNackMessage:
+                        WriteStream.WriteByte((byte)'-');
+                        break;
+
+                    case CommandMessage { Command: var cmd }:
+                        Logger.Debug?.Print(LogClass.GdbStub, $"Received Command: {cmd}");
+                        WriteStream.WriteByte((byte)'+');
+                        ProcessCommand(cmd);
+                        break;
+
+                    case ThreadBreakMessage { Context: var ctx }:
+                        DebugProcess.DebugStop();
+                        Reply($"T05thread:{ctx.ThreadUid:x};");
+                        break;
+
+                    case KillMessage:
+                        return;
+                }
+            }
+        }
+
+        private void ProcessCommand(string cmd)
+        {
+            StringStream ss = new StringStream(cmd);
+
+            switch (ss.ReadChar())
+            {
+                case '!':
+                    if (!ss.IsEmpty())
+                    {
+                        goto unknownCommand;
+                    }
+
+                    // Enable extended mode
+                    ReplyOK();
+                    break;
+                case '?':
+                    if (!ss.IsEmpty())
+                    {
+                        goto unknownCommand;
+                    }
+
+                    CommandQuery();
+                    break;
+                case 'c':
+                    CommandContinue(ss.IsEmpty() ? null : ss.ReadRemainingAsHex());
+                    break;
+                case 'D':
+                    if (!ss.IsEmpty())
+                    {
+                        goto unknownCommand;
+                    }
+
+                    CommandDetach();
+                    break;
+                case 'g':
+                    if (!ss.IsEmpty())
+                    {
+                        goto unknownCommand;
+                    }
+
+                    CommandReadRegisters();
+                    break;
+                case 'G':
+                    CommandWriteRegisters(ss);
+                    break;
+                case 'H':
+                    {
+                        char op = ss.ReadChar();
+                        ulong? threadId = ss.ReadRemainingAsThreadUid();
+                        CommandSetThread(op, threadId);
+                        break;
+                    }
+                case 'k':
+                    Logger.Notice.Print(LogClass.GdbStub, "Kill request received, detach instead");
+                    Reply("");
+                    CommandDetach();
+                    break;
+                case 'm':
+                    {
+                        ulong addr = ss.ReadUntilAsHex(',');
+                        ulong len = ss.ReadRemainingAsHex();
+                        CommandReadMemory(addr, len);
+                        break;
+                    }
+                case 'M':
+                    {
+                        ulong addr = ss.ReadUntilAsHex(',');
+                        ulong len = ss.ReadUntilAsHex(':');
+                        CommandWriteMemory(addr, len, ss);
+                        break;
+                    }
+                case 'p':
+                    {
+                        ulong gdbRegId = ss.ReadRemainingAsHex();
+                        CommandReadRegister((int)gdbRegId);
+                        break;
+                    }
+                case 'P':
+                    {
+                        ulong gdbRegId = ss.ReadUntilAsHex('=');
+                        CommandWriteRegister((int)gdbRegId, ss);
+                        break;
+                    }
+                case 'q':
+                    if (ss.ConsumeRemaining("GDBServerVersion"))
+                    {
+                        Reply($"name:Ryujinx;version:{ReleaseInformation.Version};");
+                        break;
+                    }
+
+                    if (ss.ConsumeRemaining("HostInfo"))
+                    {
+                        if (IsProcessAarch32)
+                        {
+                            Reply(
+                                $"triple:{ToHex("arm-unknown-linux-android")};endian:little;ptrsize:4;hostname:{ToHex("Ryujinx")};");
+                        }
+                        else
+                        {
+                            Reply(
+                                $"triple:{ToHex("aarch64-unknown-linux-android")};endian:little;ptrsize:8;hostname:{ToHex("Ryujinx")};");
+                        }
+                        break;
+                    }
+
+                    if (ss.ConsumeRemaining("ProcessInfo"))
+                    {
+                        if (IsProcessAarch32)
+                        {
+                            Reply(
+                                $"pid:1;cputype:12;cpusubtype:0;triple:{ToHex("arm-unknown-linux-android")};ostype:unknown;vendor:none;endian:little;ptrsize:4;");
+                        }
+                        else
+                        {
+                            Reply(
+                                $"pid:1;cputype:100000c;cpusubtype:0;triple:{ToHex("aarch64-unknown-linux-android")};ostype:unknown;vendor:none;endian:little;ptrsize:8;");
+                        }
+                        break;
+                    }
+
+                    if (ss.ConsumePrefix("Supported:") || ss.ConsumeRemaining("Supported"))
+                    {
+                        Reply("PacketSize=10000;qXfer:features:read+");
+                        break;
+                    }
+
+                    if (ss.ConsumeRemaining("fThreadInfo"))
+                    {
+                        Reply($"m{string.Join(",", DebugProcess.GetThreadUids().Select(x => $"{x:x}"))}");
+                        break;
+                    }
+
+                    if (ss.ConsumeRemaining("sThreadInfo"))
+                    {
+                        Reply("l");
+                        break;
+                    }
+
+                    if (ss.ConsumePrefix("ThreadExtraInfo,"))
+                    {
+                        ulong? threadId = ss.ReadRemainingAsThreadUid();
+                        if (threadId == null)
+                        {
+                            ReplyError();
+                            break;
+                        }
+
+                        if (DebugProcess.GetDebugState() == DebugState.Stopped)
+                        {
+                            Reply(ToHex("Stopped"));
+                        }
+                        else
+                        {
+                            Reply(ToHex("Not stopped"));
+                        }
+                        break;
+                    }
+
+                    if (ss.ConsumePrefix("Xfer:features:read:"))
+                    {
+                        string feature = ss.ReadUntil(':');
+                        ulong addr = ss.ReadUntilAsHex(',');
+                        ulong len = ss.ReadRemainingAsHex();
+
+                        if (feature == "target.xml")
+                        {
+                            feature = IsProcessAarch32 ? "target32.xml" : "target64.xml";
+                        }
+
+                        string data;
+                        if (RegisterInformation.Features.TryGetValue(feature, out data))
+                        {
+                            if (addr >= (ulong)data.Length)
+                            {
+                                Reply("l");
+                                break;
+                            }
+
+                            if (len >= (ulong)data.Length - addr)
+                            {
+                                Reply("l" + ToBinaryFormat(data.Substring((int)addr)));
+                                break;
+                            }
+                            else
+                            {
+                                Reply("m" + ToBinaryFormat(data.Substring((int)addr, (int)len)));
+                                break;
+                            }
+                        }
+                        else
+                        {
+                            Reply("E00"); // Invalid annex
+                            break;
+                        }
+                    }
+
+                    goto unknownCommand;
+                case 'Q':
+                    goto unknownCommand;
+                case 's':
+                    CommandStep(ss.IsEmpty() ? null : ss.ReadRemainingAsHex());
+                    break;
+                case 'T':
+                    {
+                        ulong? threadId = ss.ReadRemainingAsThreadUid();
+                        CommandIsAlive(threadId);
+                        break;
+                    }
+                case 'v':
+                    if (ss.ConsumeRemaining("MustReplyEmpty"))
+                    {
+                        Reply("");
+                        break;
+                    }
+                    goto unknownCommand;
+                default:
+                unknownCommand:
+                    Logger.Notice.Print(LogClass.GdbStub, $"Unknown command: {cmd}");
+                    Reply("");
+                    break;
+            }
+        }
+
+        void CommandQuery()
+        {
+            // GDB is performing initial contact. Stop everything.
+            DebugProcess.DebugStop();
+            gThread = cThread = DebugProcess.GetThreadUids().First();
+            Reply($"T05thread:{cThread:x};");
+        }
+
+        void CommandContinue(ulong? newPc)
+        {
+            if (newPc.HasValue)
+            {
+                if (cThread == null)
+                {
+                    ReplyError();
+                    return;
+                }
+
+                DebugProcess.GetThread(cThread.Value).Context.DebugPc = newPc.Value;
+            }
+
+            DebugProcess.DebugContinue();
+        }
+
+        void CommandDetach()
+        {
+            // TODO: Remove all breakpoints
+            CommandContinue(null);
+        }
+
+        void CommandReadRegisters()
+        {
+            if (gThread == null)
+            {
+                ReplyError();
+                return;
+            }
+
+            var ctx = DebugProcess.GetThread(gThread.Value).Context;
+            string registers = "";
+            if (IsProcessAarch32)
+            {
+                for (int i = 0; i < GdbRegisterCount32; i++)
+                {
+                    registers += GdbReadRegister32(ctx, i);
+                }
+            }
+            else
+            {
+                for (int i = 0; i < GdbRegisterCount64; i++)
+                {
+                    registers += GdbReadRegister64(ctx, i);
+                }
+            }
+
+            Reply(registers);
+        }
+
+        void CommandWriteRegisters(StringStream ss)
+        {
+            if (gThread == null)
+            {
+                ReplyError();
+                return;
+            }
+
+            var ctx = DebugProcess.GetThread(gThread.Value).Context;
+            if (IsProcessAarch32)
+            {
+                for (int i = 0; i < GdbRegisterCount32; i++)
+                {
+                    if (!GdbWriteRegister32(ctx, i, ss))
+                    {
+                        ReplyError();
+                        return;
+                    }
+                }
+            }
+            else
+            {
+                for (int i = 0; i < GdbRegisterCount64; i++)
+                {
+                    if (!GdbWriteRegister64(ctx, i, ss))
+                    {
+                        ReplyError();
+                        return;
+                    }
+                }
+            }
+
+            if (ss.IsEmpty())
+            {
+                ReplyOK();
+            }
+            else
+            {
+                ReplyError();
+            }
+        }
+
+        void CommandSetThread(char op, ulong? threadId)
+        {
+            if (threadId == 0 || threadId == null)
+            {
+                threadId = GetThreads().First().ThreadUid;
+            }
+
+            if (DebugProcess.GetThread(threadId.Value) == null)
+            {
+                ReplyError();
+                return;
+            }
+
+            switch (op)
+            {
+                case 'c':
+                    cThread = threadId;
+                    ReplyOK();
+                    return;
+                case 'g':
+                    gThread = threadId;
+                    ReplyOK();
+                    return;
+                default:
+                    ReplyError();
+                    return;
+            }
+        }
+
+        void CommandReadMemory(ulong addr, ulong len)
+        {
+            try
+            {
+                var data = new byte[len];
+                DebugProcess.CpuMemory.Read(addr, data);
+                Reply(ToHex(data));
+            }
+            catch (InvalidMemoryRegionException)
+            {
+                ReplyError();
+            }
+        }
+
+        void CommandWriteMemory(ulong addr, ulong len, StringStream ss)
+        {
+            try
+            {
+                var data = new byte[len];
+                for (ulong i = 0; i < len; i++)
+                {
+                    data[i] = (byte)ss.ReadLengthAsHex(2);
+                }
+
+                DebugProcess.CpuMemory.Write(addr, data);
+                DebugProcess.InvalidateCacheRegion(addr, len);
+                ReplyOK();
+            }
+            catch (InvalidMemoryRegionException)
+            {
+                ReplyError();
+            }
+        }
+
+        void CommandReadRegister(int gdbRegId)
+        {
+            if (gThread == null)
+            {
+                ReplyError();
+                return;
+            }
+
+            var ctx = DebugProcess.GetThread(gThread.Value).Context;
+            string result;
+            if (IsProcessAarch32)
+            {
+                result = GdbReadRegister32(ctx, gdbRegId);
+                if (result != null)
+                {
+                    Reply(result);
+                }
+                else
+                {
+                    ReplyError();
+                }
+            }
+            else
+            {
+                result = GdbReadRegister64(ctx, gdbRegId);
+                if (result != null)
+                {
+                    Reply(result);
+                }
+                else
+                {
+                    ReplyError();
+                }
+            }
+        }
+
+        void CommandWriteRegister(int gdbRegId, StringStream ss)
+        {
+            if (gThread == null)
+            {
+                ReplyError();
+                return;
+            }
+
+            var ctx = DebugProcess.GetThread(gThread.Value).Context;
+            if (IsProcessAarch32)
+            {
+                if (GdbWriteRegister32(ctx, gdbRegId, ss) && ss.IsEmpty())
+                {
+                    ReplyOK();
+                }
+                else
+                {
+                    ReplyError();
+                }
+            }
+            else
+            {
+                if (GdbWriteRegister64(ctx, gdbRegId, ss) && ss.IsEmpty())
+                {
+                    ReplyOK();
+                }
+                else
+                {
+                    ReplyError();
+                }
+            }
+        }
+
+        private void CommandStep(ulong? newPc)
+        {
+            if (cThread == null)
+            {
+                ReplyError();
+                return;
+            }
+
+            var thread = DebugProcess.GetThread(cThread.Value);
+
+            if (newPc.HasValue)
+            {
+                thread.Context.DebugPc = newPc.Value;
+            }
+
+            if (!DebugProcess.DebugStep(thread))
+            {
+                ReplyError();
+            }
+            else
+            {
+                Reply($"T05thread:{thread.ThreadUid:x};");
+            }
+        }
+
+        private void CommandIsAlive(ulong? threadId)
+        {
+            if (GetThreads().Any(x => x.ThreadUid == threadId))
+            {
+                ReplyOK();
+            }
+            else
+            {
+                Reply("E00");
+            }
+        }
+
+        private void Reply(string cmd)
+        {
+            Logger.Debug?.Print(LogClass.GdbStub, $"Reply: {cmd}");
+            WriteStream.Write(Encoding.ASCII.GetBytes($"${cmd}#{CalculateChecksum(cmd):x2}"));
+        }
+
+        private void ReplyOK()
+        {
+            Reply("OK");
+        }
+
+        private void ReplyError()
+        {
+            Reply("E01");
+        }
+
+        private void DebuggerThreadMain()
+        {
+            var endpoint = new IPEndPoint(IPAddress.Any, GdbStubPort);
+            ListenerSocket = new TcpListener(endpoint);
+            ListenerSocket.Start();
+            Logger.Notice.Print(LogClass.GdbStub, $"Currently waiting on {endpoint} for GDB client");
+
+            while (!_shuttingDown)
+            {
+                try
+                {
+                    ClientSocket = ListenerSocket.AcceptSocket();
+                }
+                catch (SocketException)
+                {
+                    return;
+                }
+                ClientSocket.NoDelay = true;
+                ReadStream = new NetworkStream(ClientSocket, System.IO.FileAccess.Read);
+                WriteStream = new NetworkStream(ClientSocket, System.IO.FileAccess.Write);
+                Logger.Notice.Print(LogClass.GdbStub, "GDB client connected");
+
+                while (true)
+                {
+                    try
+                    {
+                        switch (ReadStream.ReadByte())
+                        {
+                            case -1:
+                                goto eof;
+                            case '+':
+                                continue;
+                            case '-':
+                                Logger.Notice.Print(LogClass.GdbStub, "NACK received!");
+                                continue;
+                            case '\x03':
+                                Messages.Add(new BreakInMessage());
+                                break;
+                            case '$':
+                                string cmd = "";
+                                while (true)
+                                {
+                                    int x = ReadStream.ReadByte();
+                                    if (x == -1)
+                                        goto eof;
+                                    if (x == '#')
+                                        break;
+                                    cmd += (char)x;
+                                }
+
+                                string checksum = $"{(char)ReadStream.ReadByte()}{(char)ReadStream.ReadByte()}";
+                                if (checksum == $"{CalculateChecksum(cmd):x2}")
+                                {
+                                    Messages.Add(new CommandMessage(cmd));
+                                }
+                                else
+                                {
+                                    Messages.Add(new SendNackMessage());
+                                }
+
+                                break;
+                        }
+                    }
+                    catch (IOException)
+                    {
+                        goto eof;
+                    }
+                }
+
+            eof:
+                Logger.Notice.Print(LogClass.GdbStub, "GDB client lost connection");
+                ReadStream.Close();
+                ReadStream = null;
+                WriteStream.Close();
+                WriteStream = null;
+                ClientSocket.Close();
+                ClientSocket = null;
+            }
+        }
+
+        private byte CalculateChecksum(string cmd)
+        {
+            byte checksum = 0;
+            foreach (char x in cmd)
+            {
+                unchecked
+                {
+                    checksum += (byte)x;
+                }
+            }
+
+            return checksum;
+        }
+
+        private string ToHex(byte[] bytes)
+        {
+            return string.Join("", bytes.Select(x => $"{x:x2}"));
+        }
+
+        private string ToHex(string str)
+        {
+            return ToHex(Encoding.ASCII.GetBytes(str));
+        }
+
+        private string ToBinaryFormat(byte[] bytes)
+        {
+            return string.Join("", bytes.Select(x =>
+                x switch
+                {
+                    (byte)'#' => "}\x03",
+                    (byte)'$' => "}\x04",
+                    (byte)'*' => "}\x0a",
+                    (byte)'}' => "}\x5d",
+                    _ => Convert.ToChar(x).ToString(),
+                }
+            ));
+        }
+
+        private string ToBinaryFormat(string str)
+        {
+            return ToBinaryFormat(Encoding.ASCII.GetBytes(str));
+        }
+
+        public void Dispose()
+        {
+            Dispose(true);
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                _shuttingDown = true;
+
+                ListenerSocket.Stop();
+                ClientSocket?.Shutdown(SocketShutdown.Both);
+                ClientSocket?.Close();
+                ReadStream?.Close();
+                WriteStream?.Close();
+                DebuggerThread.Join();
+                Messages.Add(new KillMessage());
+                MessageHandlerThread.Join();
+                Messages.Dispose();
+            }
+        }
+
+        public void BreakHandler(IExecutionContext ctx, ulong address, int imm)
+        {
+            Logger.Notice.Print(LogClass.GdbStub, $"Break hit on thread {ctx.ThreadUid} at pc {address:x016}");
+
+            Messages.Add(new ThreadBreakMessage(ctx, address, imm));
+            DebugProcess.DebugInterruptHandler(ctx);
+        }
+
+        public void StepHandler(IExecutionContext ctx)
+        {
+            DebugProcess.DebugInterruptHandler(ctx);
+        }
+    }
+}

src/Ryujinx.HLE/Debugger/GdbSignal.cs

@@ -0,0 +1,15 @@
+namespace Ryujinx.HLE.Debugger
+{
+    enum GdbSignal
+    {
+        Zero = 0,
+        Int = 2,
+        Quit = 3,
+        Trap = 5,
+        Abort = 6,
+        Alarm = 14,
+        IO = 23,
+        XCPU = 24,
+        Unknown = 143
+    }
+}

src/Ryujinx.HLE/Debugger/GdbXml/aarch64-core.xml

@@ -0,0 +1,93 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2009-2022 Free Software Foundation, Inc.
+     Contributed by ARM Ltd.
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!DOCTYPE feature SYSTEM "gdb-target.dtd">
+<feature name="org.gnu.gdb.aarch64.core">
+  <reg name="x0" bitsize="64"/>
+  <reg name="x1" bitsize="64"/>
+  <reg name="x2" bitsize="64"/>
+  <reg name="x3" bitsize="64"/>
+  <reg name="x4" bitsize="64"/>
+  <reg name="x5" bitsize="64"/>
+  <reg name="x6" bitsize="64"/>
+  <reg name="x7" bitsize="64"/>
+  <reg name="x8" bitsize="64"/>
+  <reg name="x9" bitsize="64"/>
+  <reg name="x10" bitsize="64"/>
+  <reg name="x11" bitsize="64"/>
+  <reg name="x12" bitsize="64"/>
+  <reg name="x13" bitsize="64"/>
+  <reg name="x14" bitsize="64"/>
+  <reg name="x15" bitsize="64"/>
+  <reg name="x16" bitsize="64"/>
+  <reg name="x17" bitsize="64"/>
+  <reg name="x18" bitsize="64"/>
+  <reg name="x19" bitsize="64"/>
+  <reg name="x20" bitsize="64"/>
+  <reg name="x21" bitsize="64"/>
+  <reg name="x22" bitsize="64"/>
+  <reg name="x23" bitsize="64"/>
+  <reg name="x24" bitsize="64"/>
+  <reg name="x25" bitsize="64"/>
+  <reg name="x26" bitsize="64"/>
+  <reg name="x27" bitsize="64"/>
+  <reg name="x28" bitsize="64"/>
+  <reg name="x29" bitsize="64"/>
+  <reg name="x30" bitsize="64"/>
+  <reg name="sp" bitsize="64" type="data_ptr"/>
+
+  <reg name="pc" bitsize="64" type="code_ptr"/>
+
+  <flags id="cpsr_flags" size="4">
+    <!-- Stack Pointer.  -->
+    <field name="SP" start="0" end="0"/>
+
+    <!-- Exception Level.  -->
+    <field name="EL" start="2" end="3"/>
+    <!-- Execution state.  -->
+    <field name="nRW" start="4" end="4"/>
+
+    <!-- FIQ interrupt mask.  -->
+    <field name="F" start="6" end="6"/>
+    <!-- IRQ interrupt mask.  -->
+    <field name="I" start="7" end="7"/>
+    <!-- SError interrupt mask.  -->
+    <field name="A" start="8" end="8"/>
+    <!-- Debug exception mask.  -->
+    <field name="D" start="9" end="9"/>
+
+    <!-- ARMv8.5-A: Branch Target Identification BTYPE.  -->
+    <field name="BTYPE" start="10" end="11"/>
+
+    <!-- ARMv8.0-A: Speculative Store Bypass.  -->
+    <field name="SSBS" start="12" end="12"/>
+
+    <!-- Illegal Execution state.  -->
+    <field name="IL" start="20" end="20"/>
+    <!-- Software Step.  -->
+    <field name="SS" start="21" end="21"/>
+    <!-- ARMv8.1-A: Privileged Access Never.  -->
+    <field name="PAN" start="22" end="22"/>
+    <!-- ARMv8.2-A: User Access Override.  -->
+    <field name="UAO" start="23" end="23"/>
+    <!-- ARMv8.4-A: Data Independent Timing.  -->
+    <field name="DIT" start="24" end="24"/>
+    <!-- ARMv8.5-A: Tag Check Override.  -->
+    <field name="TCO" start="25" end="25"/>
+
+    <!-- Overflow Condition flag.  -->
+    <field name="V" start="28" end="28"/>
+    <!-- Carry Condition flag.  -->
+    <field name="C" start="29" end="29"/>
+    <!-- Zero Condition flag.  -->
+    <field name="Z" start="30" end="30"/>
+    <!-- Negative Condition flag.  -->
+    <field name="N" start="31" end="31"/>
+  </flags>
+  <reg name="cpsr" bitsize="32" type="cpsr_flags"/>
+
+</feature>

src/Ryujinx.HLE/Debugger/GdbXml/aarch64-fpu.xml

@@ -0,0 +1,159 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2009-2022 Free Software Foundation, Inc.
+     Contributed by ARM Ltd.
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!DOCTYPE feature SYSTEM "gdb-target.dtd">
+<feature name="org.gnu.gdb.aarch64.fpu">
+  <vector id="v2d" type="ieee_double" count="2"/>
+  <vector id="v2u" type="uint64" count="2"/>
+  <vector id="v2i" type="int64" count="2"/>
+  <vector id="v4f" type="ieee_single" count="4"/>
+  <vector id="v4u" type="uint32" count="4"/>
+  <vector id="v4i" type="int32" count="4"/>
+  <vector id="v8f" type="ieee_half" count="8"/>
+  <vector id="v8u" type="uint16" count="8"/>
+  <vector id="v8i" type="int16" count="8"/>
+  <vector id="v8bf16" type="bfloat16" count="8"/>
+  <vector id="v16u" type="uint8" count="16"/>
+  <vector id="v16i" type="int8" count="16"/>
+  <vector id="v1u" type="uint128" count="1"/>
+  <vector id="v1i" type="int128" count="1"/>
+  <union id="vnd">
+    <field name="f" type="v2d"/>
+    <field name="u" type="v2u"/>
+    <field name="s" type="v2i"/>
+  </union>
+  <union id="vns">
+    <field name="f" type="v4f"/>
+    <field name="u" type="v4u"/>
+    <field name="s" type="v4i"/>
+  </union>
+  <union id="vnh">
+    <field name="bf" type="v8bf16"/>
+    <field name="f" type="v8f"/>
+    <field name="u" type="v8u"/>
+    <field name="s" type="v8i"/>
+  </union>
+  <union id="vnb">
+    <field name="u" type="v16u"/>
+    <field name="s" type="v16i"/>
+  </union>
+  <union id="vnq">
+    <field name="u" type="v1u"/>
+    <field name="s" type="v1i"/>
+  </union>
+  <union id="aarch64v">
+    <field name="d" type="vnd"/>
+    <field name="s" type="vns"/>
+    <field name="h" type="vnh"/>
+    <field name="b" type="vnb"/>
+    <field name="q" type="vnq"/>
+  </union>
+  <reg name="v0" bitsize="128" type="aarch64v" regnum="34"/>
+  <reg name="v1" bitsize="128" type="aarch64v" />
+  <reg name="v2" bitsize="128" type="aarch64v" />
+  <reg name="v3" bitsize="128" type="aarch64v" />
+  <reg name="v4" bitsize="128" type="aarch64v" />
+  <reg name="v5" bitsize="128" type="aarch64v" />
+  <reg name="v6" bitsize="128" type="aarch64v" />
+  <reg name="v7" bitsize="128" type="aarch64v" />
+  <reg name="v8" bitsize="128" type="aarch64v" />
+  <reg name="v9" bitsize="128" type="aarch64v" />
+  <reg name="v10" bitsize="128" type="aarch64v"/>
+  <reg name="v11" bitsize="128" type="aarch64v"/>
+  <reg name="v12" bitsize="128" type="aarch64v"/>
+  <reg name="v13" bitsize="128" type="aarch64v"/>
+  <reg name="v14" bitsize="128" type="aarch64v"/>
+  <reg name="v15" bitsize="128" type="aarch64v"/>
+  <reg name="v16" bitsize="128" type="aarch64v"/>
+  <reg name="v17" bitsize="128" type="aarch64v"/>
+  <reg name="v18" bitsize="128" type="aarch64v"/>
+  <reg name="v19" bitsize="128" type="aarch64v"/>
+  <reg name="v20" bitsize="128" type="aarch64v"/>
+  <reg name="v21" bitsize="128" type="aarch64v"/>
+  <reg name="v22" bitsize="128" type="aarch64v"/>
+  <reg name="v23" bitsize="128" type="aarch64v"/>
+  <reg name="v24" bitsize="128" type="aarch64v"/>
+  <reg name="v25" bitsize="128" type="aarch64v"/>
+  <reg name="v26" bitsize="128" type="aarch64v"/>
+  <reg name="v27" bitsize="128" type="aarch64v"/>
+  <reg name="v28" bitsize="128" type="aarch64v"/>
+  <reg name="v29" bitsize="128" type="aarch64v"/>
+  <reg name="v30" bitsize="128" type="aarch64v"/>
+  <reg name="v31" bitsize="128" type="aarch64v"/>
+
+  <flags id="fpsr_flags" size="4">
+    <!-- Invalid Operation cumulative floating-point exception bit.  -->
+    <field name="IOC" start="0" end="0"/>
+    <!-- Divide by Zero cumulative floating-point exception bit.  -->
+    <field name="DZC" start="1" end="1"/>
+    <!-- Overflow cumulative floating-point exception bit.  -->
+    <field name="OFC" start="2" end="2"/>
+    <!-- Underflow cumulative floating-point exception bit.  -->
+    <field name="UFC" start="3" end="3"/>
+    <!-- Inexact cumulative floating-point exception bit..  -->
+    <field name="IXC" start="4" end="4"/>
+    <!-- Input Denormal cumulative floating-point exception bit.  -->
+    <field name="IDC" start="7" end="7"/>
+    <!-- Cumulative saturation bit, Advanced SIMD only.  -->
+    <field name="QC" start="27" end="27"/>
+    <!-- When AArch32 is supported at any Exception level and AArch32
+         floating-point is implemented: Overflow condition flag for AArch32
+         floating-point comparison operations.  -->
+    <field name="V" start="28" end="28"/>
+    <!-- When AArch32 is supported at any Exception level and AArch32
+         floating-point is implemented:
+         Carry condition flag for AArch32 floating-point comparison operations.
+         -->
+    <field name="C" start="29" end="29"/>
+    <!-- When AArch32 is supported at any Exception level and AArch32
+         floating-point is implemented:
+         Zero condition flag for AArch32 floating-point comparison operations.
+         -->
+    <field name="Z" start="30" end="30"/>
+    <!-- When AArch32 is supported at any Exception level and AArch32
+         floating-point is implemented:
+         Negative condition flag for AArch32 floating-point comparison
+         operations.  -->
+    <field name="N" start="31" end="31"/>
+  </flags>
+  <reg name="fpsr" bitsize="32" type="fpsr_flags"/>
+
+  <flags id="fpcr_flags" size="4">
+    <!-- Flush Inputs to Zero (part of Armv8.7).  -->
+    <field name="FIZ" start="0" end="0"/>
+    <!-- Alternate Handling (part of Armv8.7).  -->
+    <field name="AH" start="1" end="1"/>
+    <!-- Controls how the output elements other than the lowest element of the
+         vector are determined for Advanced SIMD scalar instructions (part of
+         Armv8.7).  -->
+    <field name="NEP" start="2" end="2"/>
+    <!-- Invalid Operation floating-point exception trap enable.  -->
+    <field name="IOE" start="8" end="8"/>
+    <!-- Divide by Zero floating-point exception trap enable.  -->
+    <field name="DZE" start="9" end="9"/>
+    <!-- Overflow floating-point exception trap enable.  -->
+    <field name="OFE" start="10" end="10"/>
+    <!-- Underflow floating-point exception trap enable.  -->
+    <field name="UFE" start="11" end="11"/>
+    <!-- Inexact floating-point exception trap enable.  -->
+    <field name="IXE" start="12" end="12"/>
+    <!-- Input Denormal floating-point exception trap enable.  -->
+    <field name="IDE" start="15" end="15"/>
+    <!-- Flush-to-zero mode control bit on half-precision data-processing
+         instructions.  -->
+    <field name="FZ16" start="19" end="19"/>
+    <!-- Rounding Mode control field.  -->
+    <field name="RMode" start="22" end="23"/>
+    <!-- Flush-to-zero mode control bit.  -->
+    <field name="FZ" start="24" end="24"/>
+    <!-- Default NaN mode control bit.  -->
+    <field name="DN" start="25" end="25"/>
+    <!-- Alternative half-precision control bit.  -->
+    <field name="AHP" start="26" end="26"/>
+  </flags>
+  <reg name="fpcr" bitsize="32" type="fpcr_flags"/>
+</feature>

src/Ryujinx.HLE/Debugger/GdbXml/arm-core.xml

@@ -0,0 +1,27 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2008 Free Software Foundation, Inc.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!DOCTYPE feature SYSTEM "gdb-target.dtd">
+<feature name="org.gnu.gdb.arm.core">
+  <reg name="r0" bitsize="32"/>
+  <reg name="r1" bitsize="32"/>
+  <reg name="r2" bitsize="32"/>
+  <reg name="r3" bitsize="32"/>
+  <reg name="r4" bitsize="32"/>
+  <reg name="r5" bitsize="32"/>
+  <reg name="r6" bitsize="32"/>
+  <reg name="r7" bitsize="32"/>
+  <reg name="r8" bitsize="32"/>
+  <reg name="r9" bitsize="32"/>
+  <reg name="r10" bitsize="32"/>
+  <reg name="r11" bitsize="32"/>
+  <reg name="r12" bitsize="32"/>
+  <reg name="sp" bitsize="32" type="data_ptr"/>
+  <reg name="lr" bitsize="32"/>
+  <reg name="pc" bitsize="32" type="code_ptr"/>
+  <reg name="cpsr" bitsize="32" />
+</feature>

src/Ryujinx.HLE/Debugger/GdbXml/arm-neon.xml

@@ -0,0 +1,86 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2008 Free Software Foundation, Inc.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+<!DOCTYPE feature SYSTEM "gdb-target.dtd">
+<feature name="org.gnu.gdb.arm.vfp">
+  <vector id="neon_uint8x8" type="uint8" count="8"/>
+  <vector id="neon_uint16x4" type="uint16" count="4"/>
+  <vector id="neon_uint32x2" type="uint32" count="2"/>
+  <vector id="neon_float32x2" type="ieee_single" count="2"/>
+  <union id="neon_d">
+    <field name="u8" type="neon_uint8x8"/>
+    <field name="u16" type="neon_uint16x4"/>
+    <field name="u32" type="neon_uint32x2"/>
+    <field name="u64" type="uint64"/>
+    <field name="f32" type="neon_float32x2"/>
+    <field name="f64" type="ieee_double"/>
+  </union>
+  <vector id="neon_uint8x16" type="uint8" count="16"/>
+  <vector id="neon_uint16x8" type="uint16" count="8"/>
+  <vector id="neon_uint32x4" type="uint32" count="4"/>
+  <vector id="neon_uint64x2" type="uint64" count="2"/>
+  <vector id="neon_float32x4" type="ieee_single" count="4"/>
+  <vector id="neon_float64x2" type="ieee_double" count="2"/>
+  <union id="neon_q">
+    <field name="u8" type="neon_uint8x16"/>
+    <field name="u16" type="neon_uint16x8"/>
+    <field name="u32" type="neon_uint32x4"/>
+    <field name="u64" type="neon_uint64x2"/>
+    <field name="f32" type="neon_float32x4"/>
+    <field name="f64" type="neon_float64x2"/>
+  </union>
+  <reg name="d0" bitsize="64" type="neon_d"/>
+  <reg name="d1" bitsize="64" type="neon_d"/>
+  <reg name="d2" bitsize="64" type="neon_d"/>
+  <reg name="d3" bitsize="64" type="neon_d"/>
+  <reg name="d4" bitsize="64" type="neon_d"/>
+  <reg name="d5" bitsize="64" type="neon_d"/>
+  <reg name="d6" bitsize="64" type="neon_d"/>
+  <reg name="d7" bitsize="64" type="neon_d"/>
+  <reg name="d8" bitsize="64" type="neon_d"/>
+  <reg name="d9" bitsize="64" type="neon_d"/>
+  <reg name="d10" bitsize="64" type="neon_d"/>
+  <reg name="d11" bitsize="64" type="neon_d"/>
+  <reg name="d12" bitsize="64" type="neon_d"/>
+  <reg name="d13" bitsize="64" type="neon_d"/>
+  <reg name="d14" bitsize="64" type="neon_d"/>
+  <reg name="d15" bitsize="64" type="neon_d"/>
+  <reg name="d16" bitsize="64" type="neon_d"/>
+  <reg name="d17" bitsize="64" type="neon_d"/>
+  <reg name="d18" bitsize="64" type="neon_d"/>
+  <reg name="d19" bitsize="64" type="neon_d"/>
+  <reg name="d20" bitsize="64" type="neon_d"/>
+  <reg name="d21" bitsize="64" type="neon_d"/>
+  <reg name="d22" bitsize="64" type="neon_d"/>
+  <reg name="d23" bitsize="64" type="neon_d"/>
+  <reg name="d24" bitsize="64" type="neon_d"/>
+  <reg name="d25" bitsize="64" type="neon_d"/>
+  <reg name="d26" bitsize="64" type="neon_d"/>
+  <reg name="d27" bitsize="64" type="neon_d"/>
+  <reg name="d28" bitsize="64" type="neon_d"/>
+  <reg name="d29" bitsize="64" type="neon_d"/>
+  <reg name="d30" bitsize="64" type="neon_d"/>
+  <reg name="d31" bitsize="64" type="neon_d"/>
+
+  <reg name="q0" bitsize="128" type="neon_q"/>
+  <reg name="q1" bitsize="128" type="neon_q"/>
+  <reg name="q2" bitsize="128" type="neon_q"/>
+  <reg name="q3" bitsize="128" type="neon_q"/>
+  <reg name="q4" bitsize="128" type="neon_q"/>
+  <reg name="q5" bitsize="128" type="neon_q"/>
+  <reg name="q6" bitsize="128" type="neon_q"/>
+  <reg name="q7" bitsize="128" type="neon_q"/>
+  <reg name="q8" bitsize="128" type="neon_q"/>
+  <reg name="q9" bitsize="128" type="neon_q"/>
+  <reg name="q10" bitsize="128" type="neon_q"/>
+  <reg name="q11" bitsize="128" type="neon_q"/>
+  <reg name="q12" bitsize="128" type="neon_q"/>
+  <reg name="q13" bitsize="128" type="neon_q"/>
+  <reg name="q14" bitsize="128" type="neon_q"/>
+  <reg name="q15" bitsize="128" type="neon_q"/>
+
+  <reg name="fpscr" bitsize="32" type="int" group="float"/>
+</feature>

src/Ryujinx.HLE/Debugger/GdbXml/target32.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2009-2013 Free Software Foundation, Inc.
+     Contributed by ARM Ltd.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!DOCTYPE target SYSTEM "gdb-target.dtd">
+<target>
+  <architecture>arm</architecture>
+  <xi:include href="arm-core.xml"/>
+  <xi:include href="arm-neon.xml"/>
+</target>

src/Ryujinx.HLE/Debugger/GdbXml/target64.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2009-2013 Free Software Foundation, Inc.
+     Contributed by ARM Ltd.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+
+<!DOCTYPE target SYSTEM "gdb-target.dtd">
+<target>
+  <architecture>aarch64</architecture>
+  <xi:include href="aarch64-core.xml"/>
+  <xi:include href="aarch64-fpu.xml"/>
+</target>

src/Ryujinx.HLE/Debugger/IDebuggableProcess.cs

@@ -0,0 +1,19 @@
+using Ryujinx.Cpu;
+using Ryujinx.HLE.HOS.Kernel.Threading;
+using Ryujinx.Memory;
+
+namespace Ryujinx.HLE.Debugger
+{
+    internal interface IDebuggableProcess
+    {
+        void DebugStop();
+        void DebugContinue();
+        bool DebugStep(KThread thread);
+        KThread GetThread(ulong threadUid);
+        DebugState GetDebugState();
+        ulong[] GetThreadUids();
+        public void DebugInterruptHandler(IExecutionContext ctx);
+        IVirtualMemoryManager CpuMemory { get; }
+        void InvalidateCacheRegion(ulong address, ulong size);
+    }
+}

src/Ryujinx.HLE/Debugger/Message/BreakInMessage.cs

@@ -0,0 +1,6 @@
+namespace Ryujinx.HLE.Debugger
+{
+    struct BreakInMessage : IMessage
+    {
+    }
+}

src/Ryujinx.HLE/Debugger/Message/CommandMessage.cs

@@ -0,0 +1,12 @@
+namespace Ryujinx.HLE.Debugger
+{
+    struct CommandMessage : IMessage
+    {
+        public string Command;
+
+        public CommandMessage(string cmd)
+        {
+            Command = cmd;
+        }
+    }
+}

src/Ryujinx.HLE/Debugger/Message/IMessage.cs

@@ -0,0 +1,6 @@
+namespace Ryujinx.HLE.Debugger
+{
+    interface IMessage
+    {
+    }
+}

src/Ryujinx.HLE/Debugger/Message/KillMessage.cs

@@ -0,0 +1,6 @@
+namespace Ryujinx.HLE.Debugger
+{
+    struct KillMessage : IMessage
+    {
+    }
+}

src/Ryujinx.HLE/Debugger/Message/SendNackMessage.cs

@@ -0,0 +1,6 @@
+namespace Ryujinx.HLE.Debugger
+{
+    struct SendNackMessage : IMessage
+    {
+    }
+}

src/Ryujinx.HLE/Debugger/Message/ThreadBreakMessage.cs

@@ -0,0 +1,18 @@
+using IExecutionContext = Ryujinx.Cpu.IExecutionContext;
+
+namespace Ryujinx.HLE.Debugger
+{
+    public class ThreadBreakMessage : IMessage
+    {
+        public IExecutionContext Context { get; }
+        public ulong Address { get; }
+        public int Opcode { get; }
+
+        public ThreadBreakMessage(IExecutionContext context, ulong address, int opcode)
+        {
+            Context = context;
+            Address = address;
+            Opcode = opcode;
+        }
+    }
+}

src/Ryujinx.HLE/Debugger/RegisterInformation.cs

@@ -0,0 +1,28 @@
+using System.Collections.Generic;
+using System.IO;
+
+namespace Ryujinx.HLE.Debugger
+{
+    class RegisterInformation
+    {
+        public static readonly Dictionary<string, string> Features = new()
+        {
+            { "target64.xml", GetEmbeddedResourceContent("target64.xml") },
+            { "target32.xml", GetEmbeddedResourceContent("target32.xml") },
+            { "aarch64-core.xml", GetEmbeddedResourceContent("aarch64-core.xml") },
+            { "aarch64-fpu.xml", GetEmbeddedResourceContent("aarch64-fpu.xml") },
+            { "arm-core.xml", GetEmbeddedResourceContent("arm-core.xml") },
+            { "arm-neon.xml", GetEmbeddedResourceContent("arm-neon.xml") },
+        };
+
+        private static string GetEmbeddedResourceContent(string resourceName)
+        {
+            Stream stream = System.Reflection.Assembly.GetExecutingAssembly().GetManifestResourceStream("Ryujinx.HLE.Debugger.GdbXml." + resourceName);
+            StreamReader reader = new StreamReader(stream);
+            string result = reader.ReadToEnd();
+            reader.Dispose();
+            stream.Dispose();
+            return result;
+        }
+    }
+}

src/Ryujinx.HLE/Debugger/StringStream.cs

@@ -0,0 +1,109 @@
+using System.Diagnostics;
+using System.Globalization;
+
+namespace Ryujinx.HLE.Debugger
+{
+    class StringStream
+    {
+        private readonly string Data;
+        private int Position;
+
+        public StringStream(string s)
+        {
+            Data = s;
+        }
+
+        public char ReadChar()
+        {
+            return Data[Position++];
+        }
+
+        public string ReadUntil(char needle)
+        {
+            int needlePos = Data.IndexOf(needle, Position);
+
+            if (needlePos == -1)
+            {
+                needlePos = Data.Length;
+            }
+
+            string result = Data.Substring(Position, needlePos - Position);
+            Position = needlePos + 1;
+            return result;
+        }
+
+        public string ReadLength(int len)
+        {
+            string result = Data.Substring(Position, len);
+            Position += len;
+            return result;
+        }
+
+        public string ReadRemaining()
+        {
+            string result = Data.Substring(Position);
+            Position = Data.Length;
+            return result;
+        }
+
+        public ulong ReadRemainingAsHex()
+        {
+            return ulong.Parse(ReadRemaining(), NumberStyles.HexNumber);
+        }
+
+        public ulong ReadUntilAsHex(char needle)
+        {
+            return ulong.Parse(ReadUntil(needle), NumberStyles.HexNumber);
+        }
+
+        public ulong ReadLengthAsHex(int len)
+        {
+            return ulong.Parse(ReadLength(len), NumberStyles.HexNumber);
+        }
+
+        public ulong ReadLengthAsLEHex(int len)
+        {
+            Debug.Assert(len % 2 == 0);
+
+            ulong result = 0;
+            int pos = 0;
+            while (pos < len)
+            {
+                result += ReadLengthAsHex(2) << (4 * pos);
+                pos += 2;
+            }
+            return result;
+        }
+
+        public ulong? ReadRemainingAsThreadUid()
+        {
+            string s = ReadRemaining();
+            return s == "-1" ? null : ulong.Parse(s, NumberStyles.HexNumber);
+        }
+
+        public bool ConsumePrefix(string prefix)
+        {
+            if (Data.Substring(Position).StartsWith(prefix))
+            {
+                Position += prefix.Length;
+                return true;
+            }
+            return false;
+        }
+
+        public bool ConsumeRemaining(string match)
+        {
+            if (Data.Substring(Position) == match)
+            {
+                Position += match.Length;
+                return true;
+            }
+            return false;
+        }
+
+        public bool IsEmpty()
+        {
+            return Position >= Data.Length;
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Horizon.cs

@@ -5,6 +5,7 @@ using LibHac.Fs.Shim;
 using LibHac.FsSystem;
 using LibHac.Tools.FsSystem;
 using Ryujinx.Cpu;
+using Ryujinx.HLE.Debugger;
 using Ryujinx.HLE.FileSystem;
 using Ryujinx.HLE.HOS.Kernel;
 using Ryujinx.HLE.HOS.Kernel.Memory;
@@ -500,5 +501,13 @@ namespace Ryujinx.HLE.HOS
 
             IsPaused = pause;
         }
+
+        internal IDebuggableProcess DebugGetApplicationProcess()
+        {
+            lock (KernelContext.Processes)
+            {
+                return KernelContext.Processes.Values.FirstOrDefault(x => x.IsApplication)?.DebugInterface;
+            }
+        }
     }
 }

src/Ryujinx.HLE/HOS/Kernel/Process/KProcess.cs

@@ -1,6 +1,7 @@
 using Ryujinx.Common;
 using Ryujinx.Common.Logging;
 using Ryujinx.Cpu;
+using Ryujinx.HLE.Debugger;
 using Ryujinx.HLE.Exceptions;
 using Ryujinx.HLE.HOS.Kernel.Common;
 using Ryujinx.HLE.HOS.Kernel.Memory;
@@ -11,6 +12,8 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
+using ExceptionCallback = Ryujinx.Cpu.ExceptionCallback;
+using ExceptionCallbackNoArgs = Ryujinx.Cpu.ExceptionCallbackNoArgs;
 
 namespace Ryujinx.HLE.HOS.Kernel.Process
 {
@@ -89,6 +92,8 @@ namespace Ryujinx.HLE.HOS.Kernel.Process
         public IVirtualMemoryManager CpuMemory => Context.AddressSpace;
 
         public HleProcessDebugger Debugger { get; private set; }
+        public IDebuggableProcess DebugInterface { get; private set; }
+        protected int debugState = (int)DebugState.Running;
 
         public KProcess(KernelContext context, bool allowCodeMemoryForJit = false) : base(context)
         {
@@ -110,6 +115,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Process
             _threads = [];
 
             Debugger = new HleProcessDebugger(this);
+            DebugInterface = new DebuggerInterface(this);
         }
 
         public Result InitializeKip(
@@ -679,6 +685,12 @@ namespace Ryujinx.HLE.HOS.Kernel.Process
 
                 SetState(newState);
 
+                if (KernelContext.Device.Configuration.DebuggerSuspendOnStart && IsApplication)
+                {
+                    mainThread.Suspend(ThreadSchedState.ThreadPauseFlag);
+                    debugState = (int)DebugState.Stopped;
+                }
+
                 result = mainThread.Start();
 
                 if (result != Result.Success)
@@ -727,9 +739,19 @@ namespace Ryujinx.HLE.HOS.Kernel.Process
 
         public IExecutionContext CreateExecutionContext()
         {
+            ExceptionCallback breakCallback = null;
+            ExceptionCallbackNoArgs stepCallback = null;
+
+            if (KernelContext.Device.Configuration.EnableGdbStub)
+            {
+                breakCallback = KernelContext.Device.Debugger.BreakHandler;
+                stepCallback = KernelContext.Device.Debugger.StepHandler;
+            }
+
             return Context?.CreateExecutionContext(new ExceptionCallbacks(
                 InterruptHandler,
-                null,
+                breakCallback,
+                stepCallback,
                 KernelContext.SyscallHandler.SvcCall,
                 UndefinedInstructionHandler));
         }
@@ -1174,5 +1196,157 @@ namespace Ryujinx.HLE.HOS.Kernel.Process
         {
             return Capabilities.IsSvcPermitted(svcId);
         }
+
+        private class DebuggerInterface : IDebuggableProcess
+        {
+            private Barrier StepBarrier;
+            private readonly KProcess _parent;
+            private readonly KernelContext _kernelContext;
+            private KThread steppingThread;
+
+            public DebuggerInterface(KProcess p)
+            {
+                _parent = p;
+                _kernelContext = p.KernelContext;
+                StepBarrier = new(2);
+            }
+
+            public void DebugStop()
+            {
+                if (Interlocked.CompareExchange(ref _parent.debugState, (int)DebugState.Stopping,
+                        (int)DebugState.Running) != (int)DebugState.Running)
+                {
+                    return;
+                }
+
+                _kernelContext.CriticalSection.Enter();
+                lock (_parent._threadingLock)
+                {
+                    foreach (KThread thread in _parent._threads)
+                    {
+                        thread.Suspend(ThreadSchedState.ThreadPauseFlag);
+                        thread.Context.RequestInterrupt();
+                        if (!thread.DebugHalt.WaitOne(TimeSpan.FromMilliseconds(50)))
+                        {
+                            Logger.Warning?.Print(LogClass.Kernel, $"Failed to suspend thread {thread.ThreadUid} in time.");
+                        }
+                    }
+                }
+
+                _parent.debugState = (int)DebugState.Stopped;
+                _kernelContext.CriticalSection.Leave();
+            }
+
+            public void DebugContinue()
+            {
+                if (Interlocked.CompareExchange(ref _parent.debugState, (int)DebugState.Running,
+                        (int)DebugState.Stopped) != (int)DebugState.Stopped)
+                {
+                    return;
+                }
+
+                _kernelContext.CriticalSection.Enter();
+                lock (_parent._threadingLock)
+                {
+                    foreach (KThread thread in _parent._threads)
+                    {
+                        thread.Resume(ThreadSchedState.ThreadPauseFlag);
+                    }
+                }
+                _kernelContext.CriticalSection.Leave();
+            }
+
+            public bool DebugStep(KThread target)
+            {
+                if (_parent.debugState != (int)DebugState.Stopped)
+                {
+                    return false;
+                }
+                _kernelContext.CriticalSection.Enter();
+                steppingThread = target;
+                bool waiting = target.MutexOwner != null || target.WaitingSync || target.WaitingInArbitration;
+                target.Context.RequestDebugStep();
+                if (waiting)
+                {
+                    lock (_parent._threadingLock)
+                    {
+                        foreach (KThread thread in _parent._threads)
+                        {
+                            thread.Resume(ThreadSchedState.ThreadPauseFlag);
+                        }
+                    }
+                }
+                else
+                {
+                    target.Resume(ThreadSchedState.ThreadPauseFlag);
+                }
+                _kernelContext.CriticalSection.Leave();
+
+                StepBarrier.SignalAndWait();
+
+                _kernelContext.CriticalSection.Enter();
+                steppingThread = null;
+                if (waiting)
+                {
+                    lock (_parent._threadingLock)
+                    {
+                        foreach (KThread thread in _parent._threads)
+                        {
+                            thread.Suspend(ThreadSchedState.ThreadPauseFlag);
+                        }
+                    }
+                }
+                else
+                {
+                    target.Suspend(ThreadSchedState.ThreadPauseFlag);
+                }
+                _kernelContext.CriticalSection.Leave();
+                StepBarrier.SignalAndWait();
+                return true;
+            }
+
+            public DebugState GetDebugState()
+            {
+                return (DebugState)_parent.debugState;
+            }
+
+            public ulong[] GetThreadUids()
+            {
+                lock (_parent._threadingLock)
+                {
+                    var threads = _parent._threads.Where(x => !x.TerminationRequested).ToArray();
+                    return threads.Select(x => x.ThreadUid).ToArray();
+                }
+            }
+
+            public KThread GetThread(ulong threadUid)
+            {
+                lock (_parent._threadingLock)
+                {
+                    var threads = _parent._threads.Where(x => !x.TerminationRequested).ToArray();
+                    return threads.FirstOrDefault(x => x.ThreadUid == threadUid);
+                }
+            }
+
+            public void DebugInterruptHandler(IExecutionContext ctx)
+            {
+                _kernelContext.CriticalSection.Enter();
+                bool stepping = steppingThread != null;
+                _kernelContext.CriticalSection.Leave();
+                if (stepping)
+                {
+                    StepBarrier.SignalAndWait();
+                    StepBarrier.SignalAndWait();
+                }
+                _parent.InterruptHandler(ctx);
+            }
+
+            public IVirtualMemoryManager CpuMemory { get { return _parent.CpuMemory; } }
+
+            public void InvalidateCacheRegion(ulong address, ulong size)
+            {
+                _parent.Context.InvalidateCacheRegion(address, size);
+            }
+        }
     }
 }

src/Ryujinx.HLE/HOS/Kernel/Process/ProcessExecutionContext.cs

@@ -1,5 +1,6 @@
 using ARMeilleure.State;
 using Ryujinx.Cpu;
+using System.Threading;
 
 namespace Ryujinx.HLE.HOS.Kernel.Process
 {
@@ -17,10 +18,14 @@ namespace Ryujinx.HLE.HOS.Kernel.Process
 
         public bool IsAarch32 { get => false; set { } }
 
+        public ulong ThreadUid { get; set; }
+
         public bool Running { get; private set; } = true;
 
         private readonly ulong[] _x = new ulong[32];
 
+        public ulong DebugPc { get; set; }
+
         public ulong GetX(int index) => _x[index];
         public void SetX(int index, ulong value) => _x[index] = value;
 
@@ -31,6 +36,10 @@ namespace Ryujinx.HLE.HOS.Kernel.Process
         {
         }
 
+        public void RequestDebugStep()
+        {
+        }
+
         public void StopRunning()
         {
             Running = false;

src/Ryujinx.HLE/HOS/Kernel/Threading/KScheduler.cs

@@ -301,6 +301,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
 
             currentThread.SchedulerWaitEvent.Reset();
             currentThread.ThreadContext.Unlock();
+            currentThread.DebugHalt.Set();
 
             // Wake all the threads that might be waiting until this thread context is unlocked.
             for (int core = 0; core < CpuCoresCount; core++)

src/Ryujinx.HLE/HOS/Kernel/Threading/KThread.cs

@@ -1,5 +1,6 @@
 using Ryujinx.Common.Logging;
 using Ryujinx.Cpu;
+using Ryujinx.HLE.Debugger;
 using Ryujinx.HLE.HOS.Kernel.Common;
 using Ryujinx.HLE.HOS.Kernel.Process;
 using Ryujinx.HLE.HOS.Kernel.SupervisorCall;
@@ -114,6 +115,8 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
 
         private readonly Lock _activityOperationLock = new();
 
+        internal readonly ManualResetEvent DebugHalt = new(false);
+
         public KThread(KernelContext context) : base(context)
         {
             WaitSyncObjects = new KSynchronizationObject[MaxWaitSyncObjects];
@@ -202,8 +205,10 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
             }
 
             Context.TpidrroEl0 = (long)_tlsAddress;
+            Context.DebugPc = _entrypoint;
 
             ThreadUid = KernelContext.NewThreadUid();
+            Context.ThreadUid = ThreadUid;
 
             HostThread.Name = customThreadStart != null ? $"HLE.OsThread.{ThreadUid}" : $"HLE.GuestThread.{ThreadUid}";
 
@@ -307,7 +312,9 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
         {
             KernelContext.CriticalSection.Enter();
 
-            if (Owner != null && Owner.PinnedThreads[KernelStatic.GetCurrentThread().CurrentCore] == this)
+            KThread currentThread = KernelStatic.GetCurrentThread();
+
+            if (Owner != null && currentThread != null && Owner.PinnedThreads[currentThread.CurrentCore] == this)
             {
                 Owner.UnpinThread(this);
             }
@@ -362,7 +369,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
         {
             ThreadSchedState state = PrepareForTermination();
 
-            if (state != ThreadSchedState.TerminationPending)
+            if (KernelStatic.GetCurrentThread() == this && state != ThreadSchedState.TerminationPending)
             {
                 KernelContext.Synchronization.WaitFor(new KSynchronizationObject[] { this }, -1, out _);
             }
@@ -1248,6 +1255,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
         private void ThreadStart()
         {
             _schedulerWaitEvent.WaitOne();
+            DebugHalt.Reset();
             KernelStatic.SetKernelContext(KernelContext, this);
 
             if (_customThreadStart != null)

src/Ryujinx.HLE/HleConfiguration.cs

@@ -194,6 +194,21 @@ namespace Ryujinx.HLE
         /// </summary>
         public Action RefreshInputConfig { internal get; set; }
 
+        /// <summary>
+        /// Enables gdbstub to allow for debugging of the guest .
+        /// </summary>
+        public bool EnableGdbStub { internal get; set; }
+
+        /// <summary>
+        /// A TCP port to use to expose a gdbstub for a debugger to connect to.
+        /// </summary>
+        public ushort GdbStubPort { internal get; set; }
+
+        /// <summary>
+        /// Suspend execution when starting an application
+        /// </summary>
+        public bool DebuggerSuspendOnStart { internal get; set; }
+
         /// <summary>
         ///     The desired hacky workarounds.
         /// </summary>
@@ -222,6 +237,9 @@ namespace Ryujinx.HLE
                                 bool multiplayerDisableP2p,
                                 string multiplayerLdnPassphrase,
                                 string multiplayerLdnServer,
+                                bool enableGdbStub,
+                                ushort gdbStubPort,
+                                bool debuggerSuspendOnStart,
                                 int customVSyncInterval,
                                 EnabledDirtyHack[] dirtyHacks = null)
         {
@@ -248,6 +266,9 @@ namespace Ryujinx.HLE
             MultiplayerDisableP2p = multiplayerDisableP2p;
             MultiplayerLdnPassphrase = multiplayerLdnPassphrase;
             MultiplayerLdnServer = multiplayerLdnServer;
+            EnableGdbStub = enableGdbStub;
+            GdbStubPort = gdbStubPort;
+            DebuggerSuspendOnStart = debuggerSuspendOnStart;
             Hacks = dirtyHacks ?? [];
         }
 

src/Ryujinx.HLE/Ryujinx.HLE.csproj

@@ -33,6 +33,12 @@
   </ItemGroup>
 
   <ItemGroup>
+    <None Remove="Debugger\GdbXml\aarch64-core.xml" />
+    <None Remove="Debugger\GdbXml\aarch64-fpu.xml" />
+    <None Remove="Debugger\GdbXml\arm-core.xml" />
+    <None Remove="Debugger\GdbXml\arm-neon.xml" />
+    <None Remove="Debugger\GdbXml\target64.xml" />
+    <None Remove="Debugger\GdbXml\target32.xml" />
     <None Remove="Homebrew.npdm" />
     <None Remove="HOS\Applets\SoftwareKeyboard\Resources\Logo_Ryujinx.png" />
     <None Remove="HOS\Applets\SoftwareKeyboard\Resources\Icon_BtnA.png" />
@@ -42,6 +48,12 @@
   </ItemGroup>
 
   <ItemGroup>
+    <EmbeddedResource Include="Debugger\GdbXml\aarch64-core.xml" />
+    <EmbeddedResource Include="Debugger\GdbXml\aarch64-fpu.xml" />
+    <EmbeddedResource Include="Debugger\GdbXml\arm-core.xml" />
+    <EmbeddedResource Include="Debugger\GdbXml\arm-neon.xml" />
+    <EmbeddedResource Include="Debugger\GdbXml\target64.xml" />
+    <EmbeddedResource Include="Debugger\GdbXml\target32.xml" />
     <EmbeddedResource Include="Homebrew.npdm" />
     <EmbeddedResource Include="HOS\Applets\SoftwareKeyboard\Resources\Logo_Ryujinx.png" />
     <EmbeddedResource Include="HOS\Applets\SoftwareKeyboard\Resources\Icon_BtnA.png" />

src/Ryujinx.HLE/Switch.cs

@@ -14,6 +14,7 @@ using Ryujinx.HLE.Loaders.Processes;
 using Ryujinx.HLE.UI;
 using Ryujinx.Memory;
 using System;
+using System.Threading;
 
 namespace Ryujinx.HLE
 {
@@ -41,6 +42,7 @@ namespace Ryujinx.HLE
         public Hid Hid { get; }
         public TamperMachine TamperMachine { get; }
         public IHostUIHandler UIHandler { get; }
+        public Debugger.Debugger Debugger { get; }
 
         public int CpuCoresCount = 4; // Switch has a quad-core Tegra X1 SoC
 
@@ -72,6 +74,7 @@ namespace Ryujinx.HLE
             AudioDeviceDriver = new CompatLayerHardwareDeviceDriver(Configuration.AudioDeviceDriver);
             Memory            = new MemoryBlock(Configuration.MemoryConfiguration.ToDramSize(), memoryAllocationFlags);
             Gpu               = new GpuContext(Configuration.GpuRenderer, DirtyHacks);
+            Debugger          = Configuration.EnableGdbStub ? new Debugger.Debugger(this, Configuration.GdbStubPort) : null;
             System            = new HOS.Horizon(this);
             Statistics        = new PerformanceStatistics(this);
             Hid               = new Hid(this, System.HidStorage);
@@ -173,6 +176,7 @@ namespace Ryujinx.HLE
                 AudioDeviceDriver.Dispose();
                 FileSystem.Dispose();
                 Memory.Dispose();
+                Debugger.Dispose();
 
                 TitleIDs.CurrentApplication.Value = null;
                 Shared = null;

src/Ryujinx/Headless/HeadlessRyujinx.Init.cs

@@ -338,6 +338,9 @@ namespace Ryujinx.Headless
                         false,
                         string.Empty,
                         string.Empty,
+                        options.EnableGdbStub,
+                        options.GdbStubPort,
+                        options.DebuggerSuspendOnStart,
                         options.CustomVSyncInterval
                     )
                     .Configure(

src/Ryujinx/Headless/Options.cs

@@ -423,6 +423,17 @@ namespace Ryujinx.Headless
         [Option("skip-user-profiles-manager", Required = false, Default = false, HelpText = "Enable skips the Profiles Manager popup during gameplay. Select the desired profile before starting the game")]
         public bool SkipUserProfilesManager { get; set; }
 
+        // Debug
+
+        [Option("enable-gdb-stub", Required = false, Default = false, HelpText = "Enables the GDB stub so that a developer can attach a debugger to the emulated process.")]
+        public bool EnableGdbStub { get; set; }
+
+        [Option("gdb-stub-port", Required = false, Default = 55555, HelpText = "Specifies which TCP port the GDB stub listens on.")]
+        public ushort GdbStubPort { get; set; }
+
+        [Option("suspend-on-start", Required = false, Default = false, HelpText = "Suspend execution when starting an application.")]
+        public bool DebuggerSuspendOnStart { get; set; }
+
         // Values
 
         [Value(0, MetaName = "input", HelpText = "Input to load.", Required = true)]

src/Ryujinx/Systems/AppHost.cs

@@ -218,6 +218,10 @@ namespace Ryujinx.Ava.Systems
             ConfigurationState.Instance.Multiplayer.LdnServer.Event += UpdateLdnServerState;
             ConfigurationState.Instance.Multiplayer.DisableP2p.Event += UpdateDisableP2pState;
 
+            ConfigurationState.Instance.Debug.EnableGdbStub.Event += UpdateEnableGdbStubState;
+            ConfigurationState.Instance.Debug.GdbStubPort.Event += UpdateGdbStubPortState;
+            ConfigurationState.Instance.Debug.DebuggerSuspendOnStart.Event += UpdateDebuggerSuspendOnStartState;
+
             _gpuCancellationTokenSource = new CancellationTokenSource();
             _gpuDoneEvent = new ManualResetEvent(false);
         }
@@ -564,6 +568,21 @@ namespace Ryujinx.Ava.Systems
             Device.Configuration.MultiplayerDisableP2p = e.NewValue;
         }
 
+        private void UpdateEnableGdbStubState(object sender, ReactiveEventArgs<bool> e)
+        {
+            Device.Configuration.EnableGdbStub = e.NewValue;
+        }
+
+        private void UpdateGdbStubPortState(object sender, ReactiveEventArgs<ushort> e)
+        {
+            Device.Configuration.GdbStubPort = e.NewValue;
+        }
+
+        private void UpdateDebuggerSuspendOnStartState(object sender, ReactiveEventArgs<bool> e)
+        {
+            Device.Configuration.DebuggerSuspendOnStart = e.NewValue;
+        }
+
         public void Stop()
         {
             _isActive = false;

src/Ryujinx/Systems/Configuration/ConfigurationFileFormat.cs

@@ -464,6 +464,21 @@ namespace Ryujinx.Ava.Systems.Configuration
         /// </summary>
         public bool UseHypervisor { get; set; }
 
+        /// <summary>
+        /// Enables or disables the GDB stub
+        /// </summary>
+        public bool EnableGdbStub { get; set; }
+
+        /// <summary>
+        /// Which TCP port should the GDB stub listen on
+        /// </summary>
+        public ushort GdbStubPort { get; set; }
+
+        /// <summary>
+        /// Suspend execution when starting an application
+        /// </summary>
+        public bool DebuggerSuspendOnStart { get; set; }
+
         /// <summary>
         ///     Show toggles for dirty hacks in the UI.
         /// </summary>

src/Ryujinx/Systems/Configuration/ConfigurationState.Migration.cs

@@ -156,6 +156,10 @@ namespace Ryujinx.Ava.Systems.Configuration
             Multiplayer.LdnPassphrase.Value = cff.MultiplayerLdnPassphrase;
             Multiplayer.LdnServer.Value = cff.LdnServer;
 
+            Debug.EnableGdbStub.Value = cff.EnableGdbStub;
+            Debug.GdbStubPort.Value = cff.GdbStubPort;
+            Debug.DebuggerSuspendOnStart.Value = cff.DebuggerSuspendOnStart;
+
             {
                 Hacks.ShowDirtyHacks.Value = shouldLoadFromFile ? cff.ShowDirtyHacks : Hacks.ShowDirtyHacks.Value; // Get from global config only
 

src/Ryujinx/Systems/Configuration/ConfigurationState.Model.cs

@@ -703,6 +703,37 @@ namespace Ryujinx.Ava.Systems.Configuration
             }
         }
 
+        /// <summary>
+        /// Debug configuration section
+        /// </summary>
+        public class DebugSection
+        {
+            /// <summary>
+            /// Enables or disables the GDB stub
+            /// </summary>
+            public ReactiveObject<bool> EnableGdbStub { get; private set; }
+
+            /// <summary>
+            /// Which TCP port should the GDB stub listen on
+            /// </summary>
+            public ReactiveObject<ushort> GdbStubPort { get; private set; }
+
+            /// <summary>
+            /// Suspend execution when starting an application
+            /// </summary>
+            public ReactiveObject<bool> DebuggerSuspendOnStart { get; private set; }
+
+            public DebugSection()
+            {
+                EnableGdbStub = new ReactiveObject<bool>();
+                EnableGdbStub.LogChangesToValue(nameof(EnableGdbStub));
+                GdbStubPort = new ReactiveObject<ushort>();
+                GdbStubPort.LogChangesToValue(nameof(GdbStubPort));
+                DebuggerSuspendOnStart = new ReactiveObject<bool>();
+                DebuggerSuspendOnStart.LogChangesToValue(nameof(DebuggerSuspendOnStart));
+            }
+        }
+
         public class HacksSection
         {
             /// <summary>
@@ -801,6 +832,11 @@ namespace Ryujinx.Ava.Systems.Configuration
         /// </summary>
         public MultiplayerSection Multiplayer { get; private set; }
 
+        /// <summary>
+        /// The Debug
+        /// </summary>
+        public DebugSection Debug { get; private set; }
+
         /// <summary>
         ///     The Dirty Hacks section
         /// </summary>
@@ -854,6 +890,7 @@ namespace Ryujinx.Ava.Systems.Configuration
             Graphics = new GraphicsSection();
             Hid = new HidSection();
             Multiplayer = new MultiplayerSection();
+            Debug = new DebugSection();
             Hacks = new HacksSection();
             UpdateCheckerType = new ReactiveObject<UpdaterType>();
             FocusLostActionType = new ReactiveObject<FocusLostType>();
@@ -893,6 +930,9 @@ namespace Ryujinx.Ava.Systems.Configuration
                 Multiplayer.DisableP2p,
                 Multiplayer.LdnPassphrase,
                 Multiplayer.GetLdnServer(),
+                Debug.EnableGdbStub,
+                Debug.GdbStubPort,
+                Debug.DebuggerSuspendOnStart,
                 Graphics.CustomVSyncInterval,
                 Hacks.ShowDirtyHacks ? Hacks.EnabledHacks : null);
     }

src/Ryujinx/Systems/Configuration/ConfigurationState.cs

@@ -147,6 +147,9 @@ namespace Ryujinx.Ava.Systems.Configuration
                 MultiplayerDisableP2p = Multiplayer.DisableP2p,
                 MultiplayerLdnPassphrase = Multiplayer.LdnPassphrase,
                 LdnServer = Multiplayer.LdnServer,
+                EnableGdbStub = Debug.EnableGdbStub,
+                GdbStubPort = Debug.GdbStubPort,
+                DebuggerSuspendOnStart = Debug.DebuggerSuspendOnStart,
                 ShowDirtyHacks = Hacks.ShowDirtyHacks,
                 DirtyHacks = Hacks.EnabledHacks.Select(it => it.Pack()).ToArray(),
             };
@@ -324,6 +327,9 @@ namespace Ryujinx.Ava.Systems.Configuration
                     },
                 }
             ];
+            Debug.EnableGdbStub.Value = false;
+            Debug.GdbStubPort.Value = 55555;
+            Debug.DebuggerSuspendOnStart.Value = false;
         }
 
         private static GraphicsBackend DefaultGraphicsBackend()

src/Ryujinx/UI/ViewModels/SettingsViewModel.cs

@@ -71,6 +71,10 @@ namespace Ryujinx.Ava.UI.ViewModels
         private string _ldnPassphrase;
         [ObservableProperty] private string _ldnServer;
 
+        private bool _enableGDBStub;
+        private ushort _gdbStubPort;
+        private bool _debuggerSuspendOnStart;
+
         public SettingsHacksViewModel DirtyHacks { get; }
 
         private readonly bool _isGameRunning;
@@ -387,6 +391,36 @@ namespace Ryujinx.Ava.UI.ViewModels
 
         public bool IsInvalidLdnPassphraseVisible { get; set; }
 
+        public bool EnableGdbStub
+        {
+            get => _enableGDBStub;
+            set
+            {
+                _enableGDBStub = value;
+                ConfigurationState.Instance.Debug.EnableGdbStub.Value = _enableGDBStub;
+            }
+        }
+
+        public ushort GDBStubPort
+        {
+            get => _gdbStubPort;
+            set
+            {
+                _gdbStubPort = value;
+                ConfigurationState.Instance.Debug.GdbStubPort.Value = _gdbStubPort;
+            }
+        }
+
+        public bool DebuggerSuspendOnStart
+        {
+            get => _debuggerSuspendOnStart;
+            set
+            {
+                _debuggerSuspendOnStart = value;
+                ConfigurationState.Instance.Debug.DebuggerSuspendOnStart.Value = _debuggerSuspendOnStart;
+            }
+        }
+
         public SettingsViewModel(VirtualFileSystem virtualFileSystem, ContentManager contentManager) : this()
         {
             _virtualFileSystem = virtualFileSystem;
@@ -680,10 +714,16 @@ namespace Ryujinx.Ava.UI.ViewModels
             FsGlobalAccessLogMode = config.System.FsGlobalAccessLogMode;
             OpenglDebugLevel = (int)config.Logger.GraphicsDebugLevel.Value;
 
+            // Multiplayer
             MultiplayerModeIndex = (int)config.Multiplayer.Mode.Value;
             DisableP2P = config.Multiplayer.DisableP2p;
             LdnPassphrase = config.Multiplayer.LdnPassphrase;
             LdnServer = config.Multiplayer.LdnServer;
+
+            // Debug
+            EnableGdbStub = config.Debug.EnableGdbStub.Value;
+            GDBStubPort = config.Debug.GdbStubPort.Value;
+            DebuggerSuspendOnStart = config.Debug.DebuggerSuspendOnStart.Value;
         }
 
         public void SaveSettings(bool global = false)
@@ -800,12 +840,18 @@ namespace Ryujinx.Ava.UI.ViewModels
             config.System.FsGlobalAccessLogMode.Value = FsGlobalAccessLogMode;
             config.Logger.GraphicsDebugLevel.Value = (GraphicsDebugLevel)OpenglDebugLevel;
 
+            // Multiplayer
             config.Multiplayer.LanInterfaceId.Value = _networkInterfaces[NetworkInterfaceList[NetworkInterfaceIndex]];
             config.Multiplayer.Mode.Value = (MultiplayerMode)MultiplayerModeIndex;
             config.Multiplayer.DisableP2p.Value = DisableP2P;
             config.Multiplayer.LdnPassphrase.Value = LdnPassphrase;
             config.Multiplayer.LdnServer.Value = LdnServer;
 
+            // Debug
+            config.Debug.EnableGdbStub.Value = EnableGdbStub;
+            config.Debug.GdbStubPort.Value = GDBStubPort;
+            config.Debug.DebuggerSuspendOnStart.Value = DebuggerSuspendOnStart;
+
             // Dirty Hacks
             config.Hacks.Xc2MenuSoftlockFix.Value = DirtyHacks.Xc2MenuSoftlockFix;
             config.Hacks.DisableNifmIsAnyInternetRequestAccepted.Value =

src/Ryujinx/UI/Views/Settings/SettingsDebugView.axaml

@@ -0,0 +1,64 @@
+<UserControl
+    x:Class="Ryujinx.Ava.UI.Views.Settings.SettingsDebugView"
+    xmlns="https://github.com/avaloniaui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    xmlns:ext="clr-namespace:Ryujinx.Ava.Common.Markup"
+    xmlns:helper="clr-namespace:Ryujinx.Common.Helper;assembly=Ryujinx.Common"
+    xmlns:ui="clr-namespace:FluentAvalonia.UI.Controls;assembly=FluentAvalonia"
+    xmlns:viewModels="clr-namespace:Ryujinx.Ava.UI.ViewModels"
+    mc:Ignorable="d"
+    x:DataType="viewModels:SettingsViewModel">
+    <Design.DataContext>
+        <viewModels:SettingsViewModel />
+    </Design.DataContext>
+    <ScrollViewer
+        Name="DebugPage"
+        HorizontalAlignment="Stretch"
+        VerticalAlignment="Stretch"
+        HorizontalScrollBarVisibility="Disabled"
+        VerticalScrollBarVisibility="Auto">
+        <Border Classes="settings">
+            <StackPanel
+                Margin="10"
+                HorizontalAlignment="Stretch"
+                Orientation="Vertical"
+                Spacing="10">
+                <TextBlock Classes="h1" Text="{ext:Locale SettingsTabDebugTitle}" />
+                <StackPanel
+                    Margin="10,0,0,0"
+                    HorizontalAlignment="Stretch"
+                    Orientation="Vertical">
+                    <CheckBox IsChecked="{Binding EnableGdbStub}">
+                        <TextBlock Text="{ext:Locale EnableGDBStub}"
+                                   ToolTip.Tip="{ext:Locale GDBStubToggleTooltip}" />
+                    </CheckBox>
+                </StackPanel>
+                <StackPanel
+                    Orientation="Horizontal">
+                    <TextBlock VerticalAlignment="Center"
+                               Text="{ext:Locale GDBStubPort}"
+                               Width="250" />
+                    <ui:NumberBox Value="{Binding GDBStubPort}"
+                                  Width="350"
+                                  SmallChange="1"
+                                  LargeChange="10"
+                                  SimpleNumberFormat="F0"
+                                  SpinButtonPlacementMode="Inline"
+                                  Minimum="1024"
+                                  Maximum="65535" />
+                </StackPanel>
+                <StackPanel
+                    Margin="10,0,0,0"
+                    HorizontalAlignment="Stretch"
+                    Orientation="Vertical">
+                    <CheckBox IsChecked="{Binding DebuggerSuspendOnStart}">
+                        <TextBlock Text="{ext:Locale DebuggerSuspendOnStart}"
+                                   ToolTip.Tip="{ext:Locale DebuggerSuspendOnStartTooltip}" />
+                    </CheckBox>
+                </StackPanel>
+            </StackPanel>
+        </Border>
+    </ScrollViewer>
+</UserControl>

src/Ryujinx/UI/Views/Settings/SettingsDebugView.axaml.cs

@@ -0,0 +1,13 @@
+using Avalonia.Controls;
+
+namespace Ryujinx.Ava.UI.Views.Settings
+{
+    public partial class SettingsDebugView : UserControl
+    {
+        public SettingsDebugView()
+        {
+            InitializeComponent();
+        }
+    }
+}
+

src/Ryujinx/UI/Windows/SettingsWindow.axaml

@@ -46,6 +46,7 @@
             <settings:SettingsAudioView Name="AudioPage" />
             <settings:SettingsNetworkView Name="NetworkPage" />
             <settings:SettingsLoggingView Name="LoggingPage" />
+            <settings:SettingsDebugView Name="DebugPage" />
             <settings:SettingsHacksView Name="HacksPage" />
         </Grid>
         <ui:NavigationView
@@ -100,6 +101,10 @@
                     Content="{ext:Locale SettingsTabLogging}"
                     Tag="LoggingPage"
                     IconSource="Document" />
+                <ui:NavigationViewItem
+                    Content="{ext:Locale SettingsTabDebug}"
+                    Tag="DebugPage"
+                    IconSource="Star" />
                 <ui:NavigationViewItem
                     IsVisible="{Binding ShowDirtyHacks}"
                     Content="Dirty Hacks"

src/Ryujinx/UI/Windows/SettingsWindow.axaml.cs

@@ -98,6 +98,9 @@ namespace Ryujinx.Ava.UI.Windows
                     case "LoggingPage":
                         NavPanel.Content = LoggingPage;
                         break;
+                    case "DebugPage":
+                        NavPanel.Content = DebugPage;
+                        break;
                     case nameof(HacksPage):
                         HacksPage.DataContext = ViewModel;
                         NavPanel.Content = HacksPage;