diff --git a/src/LibHac/FsSrv/DefaultFsServerObjects.cs b/src/LibHac/FsSrv/DefaultFsServerObjects.cs
index f759fea4..c97c046a 100644
--- a/src/LibHac/FsSrv/DefaultFsServerObjects.cs
+++ b/src/LibHac/FsSrv/DefaultFsServerObjects.cs
@@ -25,7 +25,7 @@ public class DefaultFsServerObjects
         var sdCard = new EmulatedSdCard();
 
         var gameCardNew = new GameCardDummy();
-        var sdmmcNew = new SdmmcApi();
+        var sdmmcNew = new SdmmcApi(fsServer);
 
         var gcStorageCreator = new EmulatedGameCardStorageCreator(gameCard);
 
diff --git a/src/LibHac/Os/Event.cs b/src/LibHac/Os/Event.cs
new file mode 100644
index 00000000..078f081c
--- /dev/null
+++ b/src/LibHac/Os/Event.cs
@@ -0,0 +1,73 @@
+using System;
+
+namespace LibHac.Os;
+
+public struct EventType
+{
+}
+
+public class Event : IDisposable
+{
+    private EventType _event;
+
+    private readonly OsState _os;
+
+    public Event(OsState os, EventClearMode clearMode)
+    {
+        _os = os;
+        _os.InitializeEvent(ref _event, signaled: false, clearMode);
+    }
+
+    public void Dispose() => _os.FinalizeEvent(ref _event);
+    public void Wait() => _os.WaitEvent(ref _event);
+    public bool TryWait() => _os.TryWaitEvent(ref _event);
+    public bool TimedWait(TimeSpan timeout) => _os.TimedWaitEvent(ref _event, timeout);
+    public void Signal() => _os.SignalEvent(ref _event);
+    public void Clear() => _os.ClearEvent(ref _event);
+    public ref EventType GetBase() => ref _event;
+}
+
+public static class EventApi
+{
+    public static void InitializeEvent(this OsState os, ref EventType eventType, bool signaled,
+        EventClearMode clearMode)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static void FinalizeEvent(this OsState os, ref EventType eventType)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static void SignalEvent(this OsState os, ref EventType eventType)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static void WaitEvent(this OsState os, ref EventType eventType)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static bool TryWaitEvent(this OsState os, ref EventType eventType)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static bool TimedWaitEvent(this OsState os, ref EventType eventType, TimeSpan timeout)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static void ClearEvent(this OsState os, ref EventType eventType)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static void InitializeMultiWaitHolder(this OsState os, ref MultiWaitHolderType multiWaitHolder,
+        ref EventType eventType)
+    {
+        throw new NotImplementedException();
+    }
+}
\ No newline at end of file
diff --git a/src/LibHac/Os/EventCommon.cs b/src/LibHac/Os/EventCommon.cs
new file mode 100644
index 00000000..4b555130
--- /dev/null
+++ b/src/LibHac/Os/EventCommon.cs
@@ -0,0 +1,7 @@
+namespace LibHac.Os;
+
+public enum EventClearMode
+{
+    ManualClear = 0,
+    AutoClear = 1
+}
\ No newline at end of file
diff --git a/src/LibHac/Os/TimerEvent.cs b/src/LibHac/Os/TimerEvent.cs
new file mode 100644
index 00000000..e0eae47a
--- /dev/null
+++ b/src/LibHac/Os/TimerEvent.cs
@@ -0,0 +1,85 @@
+using System;
+
+namespace LibHac.Os;
+
+public struct TimerEventType
+{
+}
+
+public class TimerEvent : IDisposable
+{
+    private TimerEventType _event;
+
+    private readonly OsState _os;
+
+    public TimerEvent(OsState os, EventClearMode clearMode)
+    {
+        _os = os;
+        _os.InitializeTimerEvent(ref _event, clearMode);
+    }
+
+    public void Dispose() => _os.FinalizeTimerEvent(ref _event);
+    public void StartOneShot(TimeSpan firstTime) => _os.StartOneShotTimerEvent(ref _event, firstTime);
+    public void StartPeriodic(TimeSpan firstTime, TimeSpan interval) => _os.StartPeriodicTimerEvent(ref _event, firstTime, interval);
+    public void Stop() => _os.StopTimerEvent(ref _event);
+    public void Wait() => _os.WaitTimerEvent(ref _event);
+    public bool TryWait() => _os.TryWaitTimerEvent(ref _event);
+    public void Signal() => _os.SignalTimerEvent(ref _event);
+    public void Clear() => _os.ClearTimerEvent(ref _event);
+    public ref TimerEventType GetBase() => ref _event;
+}
+
+public static class TimerEventApi
+{
+    public static void InitializeTimerEvent(this OsState os, ref TimerEventType eventType, EventClearMode clearMode)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static void FinalizeTimerEvent(this OsState os, ref TimerEventType eventType)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static void StartOneShotTimerEvent(this OsState os, ref TimerEventType eventType, TimeSpan firstTime)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static void StartPeriodicTimerEvent(this OsState os, ref TimerEventType eventType, TimeSpan firstTime,
+        TimeSpan interval)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static void StopTimerEvent(this OsState os, ref TimerEventType eventType)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static void SignalTimerEvent(this OsState os, ref TimerEventType eventType)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static void ClearTimerEvent(this OsState os, ref TimerEventType eventType)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static void WaitTimerEvent(this OsState os, ref TimerEventType eventType)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static bool TryWaitTimerEvent(this OsState os, ref TimerEventType eventType)
+    {
+        throw new NotImplementedException();
+    }
+
+    public static void InitializeMultiWaitHolder(this OsState os, ref MultiWaitHolderType multiWaitHolder,
+        ref TimerEventType eventType)
+    {
+        throw new NotImplementedException();
+    }
+}
\ No newline at end of file
diff --git a/src/LibHac/Sdmmc/Common.cs b/src/LibHac/Sdmmc/Common.cs
index 4ee2b2e1..30b35194 100644
--- a/src/LibHac/Sdmmc/Common.cs
+++ b/src/LibHac/Sdmmc/Common.cs
@@ -1,4 +1,5 @@
 using System;
+using LibHac.FsSrv;
 
 namespace LibHac.Sdmmc;
 
@@ -60,6 +61,14 @@ public partial class SdmmcApi
     public const int DeviceCidSize = 0x10;
     public const int DeviceCsdSize = 0x10;
 
+    private FileSystemServer _fsServer;
+    internal HorizonClient Hos => _fsServer.Hos;
+
+    public SdmmcApi(FileSystemServer fsServer)
+    {
+        _fsServer = fsServer;
+    }
+
     public void SwitchToPcvClockResetControl()
     {
         throw new NotImplementedException();
diff --git a/src/LibHac/SdmmcSrv/PatrolReader.cs b/src/LibHac/SdmmcSrv/PatrolReader.cs
index 14a9744b..c30d4b13 100644
--- a/src/LibHac/SdmmcSrv/PatrolReader.cs
+++ b/src/LibHac/SdmmcSrv/PatrolReader.cs
@@ -1,73 +1,404 @@
 using System;
+using LibHac.Common;
+using LibHac.Crypto;
+using LibHac.Diag;
+using LibHac.Fs;
+using LibHac.FsSystem;
 using LibHac.Os;
 using LibHac.Sdmmc;
+using static LibHac.SdmmcSrv.Common;
+using MmcPartition = LibHac.Sdmmc.MmcPartition;
 
 namespace LibHac.SdmmcSrv;
 
+/// <summary>
+/// Performs regular patrol reads on the internal MMC.
+/// </summary>
+/// <remarks><para>The patrol reader will read sequential half-megabyte blocks of data from the internal MMC,
+/// starting at the beginning of the storage, progressing to the end, and then looping back to the beginning.
+/// This helps with data integrity by ensuring the entire MMC is regularly read.</para>
+/// <para>Every 6 seconds the patrol reader will read a half-megabyte block from the MMC.
+/// Every 2 hours it will save the current state of the patrol read to Boot Partition 1 on the MMC.
+/// This state contains the next sector index to be read and the number of times the MMC has been patrolled
+/// from start to finish.</para>
+/// <para>Based on nnSdk 14.3.0 (FS 14.1.0)</para></remarks>
 internal class PatrolReader
 {
+    // Note: This class won't work until events and timer events are properly implemented.
+
+    private const int MacSize = HmacSha256.HashSize;
+
+    /// <summary>
+    /// The patrol reader state that's stored in Boot Partition 1.
+    /// </summary>
+    public struct State
+    {
+        public uint CurrentSector;
+        public uint PatrolCount;
+    }
+
+    public enum ThreadState
+    {
+        Stop,
+        Active,
+        Sleep
+    }
+
+    private readonly int _macSize;
+    private readonly MmcPartition _statePartition;
+    private readonly int _patrolStateOffset;
+    private readonly int _patrolStateSize;
+    private readonly int _saveStateIntervalSeconds;
+    private readonly int _patrolReadSize;
+    private readonly int _waitTimeAfterAllocationSuccess;
+    private readonly int _waitTimeAfterAllocationFailure;
+    private readonly int _firstRunDelaySeconds;
+    private uint _deviceCapacitySectors;
+    private State _patrolState;
+    private bool _isPatrolStateLoaded;
+    private SdkMutex _mutex;
+    private bool _areEventsInitialized;
+    private ThreadState _threadState;
+    // private Thread _patrolReaderThread;
+    private Event _stateChangeRequestedEvent;
+    private Event _stateChangeCompletedEvent;
+    private ulong _allocateSuccessCount;
+    private ulong _allocateFailureCount;
+
+    // LibHac addition
+    private SdmmcApi _sdmmc;
+
+    private static ReadOnlySpan<byte> PatrolStateKey => "U{W5>1Kq#Gt`f6r86o`9|*||hTy9U2C\0"u8;
+
     public PatrolReader(SdkMutex mutex, SdmmcApi sdmmc)
     {
-        throw new NotImplementedException();
+        _macSize = MacSize;
+        _statePartition = MmcPartition.BootPartition1;
+        _patrolStateOffset = 0x184000;
+        _patrolStateSize = 0x200;
+        _saveStateIntervalSeconds = 7200;
+        _patrolReadSize = 0x80000;
+        _waitTimeAfterAllocationSuccess = 6;
+        _waitTimeAfterAllocationFailure = 1;
+        _firstRunDelaySeconds = 18;
+        _isPatrolStateLoaded = false;
+        _mutex = mutex;
+        _areEventsInitialized = false;
+        _threadState = ThreadState.Stop;
+        _allocateSuccessCount = 0;
+        _allocateFailureCount = 0;
+
+        _sdmmc = sdmmc;
     }
 
     public void Dispose()
     {
-        throw new NotImplementedException();
+        FinalizeObject();
     }
 
     public static void PatrolReaderThreadEntry(object args)
     {
-        throw new NotImplementedException();
+        if (args is PatrolReader reader)
+        {
+            reader.PatrolReaderThread();
+        }
+        else
+        {
+            Abort.DoAbort($"Expected an argument of type {nameof(PatrolReader)} in {nameof(PatrolReaderThreadEntry)}");
+        }
     }
 
-    public void FinalizeObject()
+    private void FinalizeObject()
     {
-        throw new NotImplementedException();
+        if (_areEventsInitialized)
+        {
+            if (_threadState == ThreadState.Sleep)
+            {
+                Resume();
+            }
+
+            if (_threadState == ThreadState.Active)
+            {
+                Stop();
+            }
+
+            _stateChangeRequestedEvent.Dispose();
+            _stateChangeCompletedEvent.Dispose();
+
+            _areEventsInitialized = false;
+        }
     }
 
     public Result GetPatrolCount(out uint outCount)
     {
-        throw new NotImplementedException();
+        UnsafeHelpers.SkipParamInit(out outCount);
+
+        if (!_isPatrolStateLoaded)
+            return ResultFs.HasNotGottenPatrolCount.Log();
+
+        outCount = _patrolState.PatrolCount;
+        return Result.Success;
     }
 
     public void GetAndClearAllocateCount(out ulong outSuccessCount, out ulong outFailureCount)
     {
-        throw new NotImplementedException();
+        using ScopedLock<SdkMutex> scopedLock = ScopedLock.Lock(ref _mutex);
+
+        outSuccessCount = _allocateSuccessCount;
+        outFailureCount = _allocateFailureCount;
+
+        _allocateSuccessCount = 0;
+        _allocateFailureCount = 0;
     }
 
-    public bool LoadState()
+    private bool LoadState()
     {
-        throw new NotImplementedException();
+        using var pooledBuffer = new PooledBuffer(_patrolStateSize, 1);
+        if (pooledBuffer.GetSize() < _patrolStateSize)
+            return false;
+
+        using ScopedLock<SdkMutex> scopedLock = ScopedLock.Lock(ref _mutex);
+
+        Abort.DoAbortUnlessSuccess(_sdmmc.SelectMmcPartition(Port.Mmc0, _statePartition));
+
+        try
+        {
+            Result res = _sdmmc.GetDeviceMemoryCapacity(out _deviceCapacitySectors, Port.Mmc0);
+            if (res.IsFailure())
+            {
+                return false;
+            }
+
+            Span<byte> patrolStateBuffer = pooledBuffer.GetBuffer().Slice(0, _patrolStateSize);
+
+            res = _sdmmc.Read(patrolStateBuffer, Port.Mmc0, BytesToSectors(_patrolStateOffset),
+                BytesToSectors(_patrolStateSize));
+
+            if (res.IsFailure())
+            {
+                return false;
+            }
+
+            Span<byte> mac = stackalloc byte[MacSize];
+
+            // Load an empty state if the verification fails.
+            _patrolState = default;
+
+            HmacSha256.GenerateHmacSha256(mac, patrolStateBuffer.Slice(_macSize), PatrolStateKey);
+
+            if (CryptoUtil.IsSameBytes(mac, patrolStateBuffer, _macSize))
+            {
+                ref State readState = ref SpanHelpers.AsStruct<State>(patrolStateBuffer.Slice(_macSize));
+
+                if (readState.CurrentSector + BytesToSectors(_patrolReadSize) <= _deviceCapacitySectors)
+                {
+                    _patrolState = readState;
+                }
+            }
+
+            return true;
+        }
+        finally
+        {
+            Abort.DoAbortUnlessSuccess(_sdmmc.SelectMmcPartition(Port.Mmc0, MmcPartition.UserData));
+        }
     }
 
-    public bool SaveState()
+    private void SaveState()
     {
-        throw new NotImplementedException();
+        using var pooledBuffer = new PooledBuffer(_patrolStateSize, 1);
+
+        if (pooledBuffer.GetSize() < _patrolStateSize)
+            return;
+
+        using ScopedLock<SdkMutex> scopedLock = ScopedLock.Lock(ref _mutex);
+
+        Span<byte> patrolStateBuffer = pooledBuffer.GetBuffer().Slice(0, _patrolStateSize);
+        patrolStateBuffer.Clear();
+
+        SpanHelpers.AsStruct<State>(patrolStateBuffer) = _patrolState;
+
+        HmacSha256.GenerateHmacSha256(patrolStateBuffer.Slice(0, _macSize), patrolStateBuffer.Slice(_macSize),
+            PatrolStateKey);
+
+        Abort.DoAbortUnlessSuccess(_sdmmc.SelectMmcPartition(Port.Mmc0, _statePartition));
+
+        try
+        {
+            _sdmmc.Write(Port.Mmc0, BytesToSectors(_patrolStateOffset), BytesToSectors(_patrolStateSize),
+                patrolStateBuffer);
+        }
+        finally
+        {
+            Abort.DoAbortUnlessSuccess(_sdmmc.SelectMmcPartition(Port.Mmc0, MmcPartition.UserData));
+        }
+    }
+
+    private bool DoPatrolRead()
+    {
+        using var pooledBuffer = new PooledBuffer(_patrolReadSize, 1);
+        using ScopedLock<SdkMutex> scopedLock = ScopedLock.Lock(ref _mutex);
+
+        if (pooledBuffer.GetSize() < _patrolReadSize)
+        {
+            if (_allocateFailureCount != ulong.MaxValue)
+                _allocateFailureCount++;
+
+            return false;
+        }
+
+        if (_allocateSuccessCount != ulong.MaxValue)
+            _allocateSuccessCount++;
+
+        _sdmmc.Read(pooledBuffer.GetBuffer().Slice(0, _patrolReadSize), Port.Mmc0, _patrolState.CurrentSector,
+            BytesToSectors(_patrolReadSize)).IgnoreResult();
+
+        _patrolState.CurrentSector += BytesToSectors(_patrolReadSize);
+
+        if (_patrolState.CurrentSector + BytesToSectors(_patrolReadSize) > _deviceCapacitySectors)
+        {
+            _patrolState.CurrentSector = 0;
+            _patrolState.PatrolCount++;
+        }
+
+        return true;
     }
 
     public void Start()
     {
-        throw new NotImplementedException();
+        Assert.SdkAssert(_threadState is ThreadState.Active or ThreadState.Stop);
+
+        if (_threadState == ThreadState.Stop)
+        {
+            if (!_areEventsInitialized)
+            {
+                _areEventsInitialized = true;
+                _threadState = ThreadState.Stop;
+
+                _stateChangeRequestedEvent = new Event(_sdmmc.Hos.Os, EventClearMode.AutoClear);
+                _stateChangeCompletedEvent = new Event(_sdmmc.Hos.Os, EventClearMode.AutoClear);
+            }
+
+            _threadState = ThreadState.Active;
+
+            // CreateThread(_patrolReaderThread, PatrolReaderThreadEntry, this, pPatrolReaderStack, priority);
+            // SetThreadNamePointer(_patrolReaderThread, "nn.fs.PatrolReader"u8);
+            // StartThread(_patrolReaderThread);
+        }
     }
 
     public void Stop()
     {
-        throw new NotImplementedException();
+        Assert.SdkAssert(_threadState is ThreadState.Active or ThreadState.Stop or ThreadState.Sleep);
+
+        if (_threadState != ThreadState.Stop)
+        {
+            _threadState = ThreadState.Stop;
+            _stateChangeRequestedEvent.Signal();
+
+            // WaitThread(_patrolReaderThread);
+            // DestroyThread(_patrolReaderThread);
+        }
     }
 
     public void Sleep()
     {
-        throw new NotImplementedException();
+        Assert.SdkAssert(_threadState is ThreadState.Active or ThreadState.Sleep);
+
+        if (_threadState == ThreadState.Active)
+        {
+            _threadState = ThreadState.Sleep;
+
+            _stateChangeRequestedEvent.Signal();
+            _stateChangeCompletedEvent.Wait();
+        }
     }
 
     public void Resume()
     {
-        throw new NotImplementedException();
+        Assert.SdkAssert(_threadState is ThreadState.Active or ThreadState.Sleep);
+
+        if (_threadState == ThreadState.Sleep)
+        {
+            _threadState = ThreadState.Active;
+
+            _stateChangeRequestedEvent.Signal();
+            _stateChangeCompletedEvent.Wait();
+        }
     }
 
-    public void PatrolReaderThread()
+    private void PatrolReaderThread()
     {
-        throw new NotImplementedException();
+        // Missing: SetServiceContext()
+
+        using var timer = new TimerEvent(_sdmmc.Hos.Os, EventClearMode.AutoClear);
+
+        timer.StartPeriodic(TimeSpan.FromSeconds(_firstRunDelaySeconds), TimeSpan.FromSeconds(_saveStateIntervalSeconds));
+
+        int currentWaitTime = _waitTimeAfterAllocationSuccess;
+
+        while (true)
+        {
+            // Wait until the next thread state change or until the next patrol read should be done.
+            if (_stateChangeRequestedEvent.TimedWait(TimeSpan.FromSeconds(currentWaitTime)))
+            {
+                if (_threadState == ThreadState.Stop)
+                {
+                    break;
+                }
+
+                if (_threadState == ThreadState.Sleep)
+                {
+                    // Acknowledge the request to sleep and wait for the next state change.
+                    _stateChangeCompletedEvent.Signal();
+                    _stateChangeRequestedEvent.Wait();
+
+                    if (_threadState == ThreadState.Stop)
+                    {
+                        break;
+                    }
+
+                    if (_threadState == ThreadState.Active)
+                    {
+                        _stateChangeCompletedEvent.Signal();
+                        continue;
+                    }
+
+                    Assert.SdkAssert(false);
+                }
+            }
+
+            if (!_isPatrolStateLoaded)
+            {
+                // The patrol state will be loaded a single time when the console is booted.
+                // Don't load the patrol state or do patrol reads until the specified amount
+                // of time has past since creating the Patrol Reader.
+                if (!timer.TryWait() || !LoadState())
+                {
+                    continue;
+                }
+
+                _isPatrolStateLoaded = true;
+            }
+
+            if (DoPatrolRead())
+            {
+                currentWaitTime = _waitTimeAfterAllocationSuccess;
+            }
+            else
+            {
+                currentWaitTime = _waitTimeAfterAllocationFailure;
+            }
+
+            // Save the patrol state periodically once the specified amount of time has passed since the last save.
+            if (timer.TryWait())
+            {
+                SaveState();
+            }
+        }
+
+        // Save the patrol state if necessary when shutting down.
+        if (_isPatrolStateLoaded)
+            SaveState();
     }
 }
\ No newline at end of file