Use a single device aligned buffer.

Aaru.Devices/Linux/Command.cs

@@ -64,6 +64,8 @@ partial class Device
                                      _                           => ScsiIoctlDirection.Unknown
                                  };
 
+        EnsureCapacityAligned((nuint)buffer.Length);
+
         var ioHdr = new SgIoHdrT();
 
         ioHdr.interface_id    = 'S';
@@ -71,13 +73,14 @@ partial class Device
         ioHdr.mx_sb_len       = (byte)SenseBuffer.Length;
         ioHdr.dxfer_direction = dir;
         ioHdr.dxfer_len       = (uint)buffer.Length;
-        ioHdr.dxferp          = Marshal.AllocHGlobal(buffer.Length);
+        ioHdr.dxferp          = (IntPtr)_nativeBuffer;
         ioHdr.cmdp            = (IntPtr)CdbPtr;
         ioHdr.sbp             = (IntPtr)SensePtr;
         ioHdr.timeout         = timeout * 1000;
         ioHdr.flags           = (uint)SgFlags.DirectIo;
 
-        Marshal.Copy(buffer, 0, ioHdr.dxferp, buffer.Length);
+        // OUT or bidirectional → pre‑fill from managed buffer
+        if(direction != ScsiDirection.In) buffer.AsSpan().CopyTo(new Span<byte>((void*)_nativeBuffer, buffer.Length));
 
         var cmdStopWatch = new Stopwatch();
         cmdStopWatch.Start();
@@ -86,14 +89,13 @@ partial class Device
 
         if(error < 0) error = Marshal.GetLastWin32Error();
 
-        Marshal.Copy(ioHdr.dxferp, buffer, 0, buffer.Length);
+        // IN or bidirectional → copy back into managed buffer
+        if(direction != ScsiDirection.Out) new Span<byte>((void*)_nativeBuffer, buffer.Length).CopyTo(buffer);
 
         sense |= (ioHdr.info & SgInfo.OkMask) != SgInfo.Ok;
 
         duration = ioHdr.duration > 0 ? ioHdr.duration : cmdStopWatch.Elapsed.TotalMilliseconds;
 
-        Marshal.FreeHGlobal(ioHdr.dxferp);
-
         return error;
     }
 

Aaru.Devices/Linux/Device.cs

@@ -33,6 +33,7 @@
 using System;
 using System.Globalization;
 using System.IO;
+using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
 using Aaru.CommonTypes.Enums;
 using Aaru.CommonTypes.Interop;
@@ -47,14 +48,42 @@ namespace Aaru.Devices.Linux;
 
 /// <inheritdoc />
 [SupportedOSPlatform("linux")]
-partial class Device : Devices.Device
+partial class Device : Devices.Device, IDisposable
 {
+    private const nuint ALIGNMENT = 64;
+    private       nuint _capacity;
     /// <summary>Gets the file handle representing this device</summary>
     /// <value>The file handle</value>
     int _fileDescriptor;
 
+// Persistent, aligned native buffer
+    private nuint _nativeBuffer;
+
     Device() {}
 
+#region IDisposable Members
+
+    public new unsafe void Dispose()
+    {
+        if(_nativeBuffer == 0) return;
+        NativeMemory.AlignedFree((void*)_nativeBuffer);
+        _nativeBuffer = 0;
+        _capacity     = 0;
+    }
+
+#endregion
+
+
+    private unsafe void EnsureCapacityAligned(nuint size)
+    {
+        if(size <= _capacity) return;
+
+        if(_nativeBuffer != 0) NativeMemory.AlignedFree((void*)_nativeBuffer);
+
+        _nativeBuffer = (nuint)NativeMemory.AlignedAlloc(size, ALIGNMENT);
+        _capacity     = size;
+    }
+
     internal new static Device Create(string devicePath, out ErrorNumber errno)
     {
         errno = ErrorNumber.NoError;

Aaru.Devices/Windows/Command.cs

@@ -44,8 +44,8 @@ namespace Aaru.Devices.Windows;
 partial class Device
 {
     /// <inheritdoc />
-    public override int SendScsiCommand(Span<byte> cdb,      ref byte[] buffer, uint timeout, ScsiDirection direction,
+    public override unsafe int SendScsiCommand(Span<byte> cdb, ref byte[] buffer, uint timeout, ScsiDirection direction,
-                                        out double duration, out bool   sense)
+                                               out double duration, out bool sense)
     {
         // We need a timeout
         if(timeout == 0) timeout = Timeout > 0 ? Timeout : 15;
@@ -62,6 +62,8 @@ partial class Device
                                      _                 => ScsiIoctlDirection.Unspecified
                                  };
 
+        EnsureCapacityAligned((nuint)buffer.Length);
+
         var sptdSb = new ScsiPassThroughDirectAndSenseBuffer
         {
             SenseBuf = new byte[32],
@@ -73,7 +75,7 @@ partial class Device
                 DataIn             = dir,
                 DataTransferLength = (uint)buffer.Length,
                 TimeOutValue       = timeout,
-                DataBuffer         = Marshal.AllocHGlobal(buffer.Length)
+                DataBuffer         = (IntPtr)_nativeBuffer
             }
         };
 
@@ -81,11 +83,12 @@ partial class Device
         sptdSb.sptd.SenseInfoOffset = (uint)Marshal.SizeOf(sptdSb.sptd);
         cdb.CopyTo(sptdSb.sptd.Cdb);
 
+// OUT or BiDir → pre‑copy
+        if(direction != ScsiDirection.In) buffer.AsSpan().CopyTo(new Span<byte>((void*)_nativeBuffer, buffer.Length));
+
         uint k     = 0;
         int  error = 0;
 
-        Marshal.Copy(buffer, 0, sptdSb.sptd.DataBuffer, buffer.Length);
-
         var cmdStopwatch = new Stopwatch();
         cmdStopwatch.Start();
 
@@ -102,7 +105,7 @@ partial class Device
 
         if(hasError) error = Marshal.GetLastWin32Error();
 
-        Marshal.Copy(sptdSb.sptd.DataBuffer, buffer, 0, buffer.Length);
+        if(direction != ScsiDirection.Out) new Span<byte>((void*)_nativeBuffer, buffer.Length).CopyTo(buffer);
 
         sense |= sptdSb.sptd.ScsiStatus != 0;
 
@@ -110,8 +113,6 @@ partial class Device
 
         duration = cmdStopwatch.Elapsed.TotalMilliseconds;
 
-        Marshal.FreeHGlobal(sptdSb.sptd.DataBuffer);
-
         return error;
     }
 

Aaru.Devices/Windows/Device.cs

@@ -43,14 +43,40 @@ namespace Aaru.Devices.Windows;
 
 /// <inheritdoc />
 [SupportedOSPlatform("windows")]
-partial class Device : Devices.Device
+partial class Device : Devices.Device, IDisposable
 {
+    private const nuint ALIGNMENT = 64;
+    private       nuint _capacity;
     /// <summary>Gets the file handle representing this device</summary>
     /// <value>The file handle</value>
     SafeFileHandle _fileHandle;
+    private nuint _nativeBuffer;
 
     Device() {}
 
+#region IDisposable Members
+
+    public new unsafe void Dispose()
+    {
+        if(_nativeBuffer == 0) return;
+        NativeMemory.AlignedFree((void*)_nativeBuffer);
+        _nativeBuffer = 0;
+        _capacity     = 0;
+    }
+
+#endregion
+
+    private unsafe void EnsureCapacityAligned(nuint size)
+    {
+        if(size <= _capacity) return;
+
+        if(_nativeBuffer != 0) NativeMemory.AlignedFree((void*)_nativeBuffer);
+
+        _nativeBuffer = (nuint)NativeMemory.AlignedAlloc(size, ALIGNMENT);
+
+        _capacity = size;
+    }
+
     internal new static Device Create(string devicePath, out ErrorNumber errno)
     {
         errno = ErrorNumber.NoError;
@@ -102,10 +128,10 @@ partial class Device : Devices.Device
         };
 
         IntPtr descriptorPtr = Marshal.AllocHGlobal(1000);
-        var    descriptorB   = new byte[1000];
+        byte[] descriptorB   = new byte[1000];
 
         uint returned = 0;
-        var  error    = 0;
+        int  error    = 0;
 
         bool hasError = !Extern.DeviceIoControlStorageQuery(dev._fileHandle,
                                                             WindowsIoctl.IoctlStorageQueryProperty,
@@ -203,7 +229,7 @@ partial class Device : Devices.Device
 
         if(IsSdhci(dev._fileHandle))
         {
-            var sdBuffer = new byte[16];
+            byte[] sdBuffer = new byte[16];
 
             dev.LastError = dev.SendMmcCommand(MmcCommands.SendCsd,
                                                false,