fix(core): lazy dlsym stub materialization, COW snapshots and deferred bootstrap logging (#94)

* fix(core): implement 4-tier lazy dlsym stub materialization and argument normalization

Enforce transactional and thread-safe resolution for standalone ELF bootstrapper pipelines. - Implement a 4-tier additive fallback cascade (T0: runtime symbols, T1: import entries scan, T2: Aerolib mapping, T3: runtime slack-pool lazy stub allocation at 0x7000_0000_0000). - Fix UnmanagedCallersOnly CLR runtime crashes on second bootstrap by adding NormalizeKernelDynlibDlsymArguments to detect and swap mirrored (symbol, handle) register inputs via rigorous pointer bounds verification. - Protect failure paths via CompleteKernelDynlibDlsymFailure, cleanly zero-filling target outputAddress buffers and returns Rax = -1 with zero managed logging execution in hot native paths.

* fix(core): harden lazy-stub diagnostics with COW snapshots and deferred bootstrap logging

Follow-up to lazy stub pool copy-on-write publishing in TryGetOrCreateLazyImportStub. - Snapshot _importEntries in ProbeReturnRip before near-call and PLT import lookup loops to prevent torn iteration during concurrent array replacement. - Defer SHARPEMU_LOG_BOOTSTRAP output: hot path records raw register slots in a ring buffer under lock; TryReadAsciiZ and Console.Error run only after import handler completion via DrainDeferredBootstrapTraces. - Normalize bootstrap dynlib register order at DispatchImport gateway entry before any logging or trace reads, so swapped RDI/RSI on Import#2 cannot fault the native gateway when bootstrap tracing is enabled. - Resolve lazy stub pool bounds from the full SelfLoader-mapped import region via VirtualQuery instead of a hardcoded 4 KiB cap. - Use ConcurrentDictionary for runtime symbol registration during concurrent dlsym. - Emit distinct [LOADER][WARN] reasons when import stub region resolution fails versus lazy stub pool exhaustion.

src/SharpEmu.Core/Cpu/Native/DirectExecutionBackend.Diagnostics.cs

@@ -38,6 +38,71 @@ public sealed partial class DirectExecutionBackend
 		}
 	}
 
+	private void RecordDeferredBootstrapTrace(
+		long dispatchIndex,
+		ulong op,
+		ulong symbolPointer,
+		ulong outputPointer,
+		ulong returnRip)
+	{
+		lock (_deferredBootstrapTraceGate)
+		{
+			_deferredBootstrapTrace[_deferredBootstrapTraceWriteIndex] = new DeferredBootstrapTraceEntry(
+				dispatchIndex,
+				op,
+				symbolPointer,
+				outputPointer,
+				returnRip);
+			_deferredBootstrapTraceWriteIndex =
+				(_deferredBootstrapTraceWriteIndex + 1) % _deferredBootstrapTrace.Length;
+			if (_deferredBootstrapTraceCount < _deferredBootstrapTrace.Length)
+			{
+				_deferredBootstrapTraceCount++;
+			}
+		}
+	}
+
+	private void DrainDeferredBootstrapTraces()
+	{
+		if (!_logBootstrap)
+		{
+			return;
+		}
+
+		DeferredBootstrapTraceEntry[] pending;
+		lock (_deferredBootstrapTraceGate)
+		{
+			if (_deferredBootstrapTraceCount == 0)
+			{
+				return;
+			}
+
+			pending = new DeferredBootstrapTraceEntry[_deferredBootstrapTraceCount];
+			var readIndex = (_deferredBootstrapTraceWriteIndex - _deferredBootstrapTraceCount +
+				_deferredBootstrapTrace.Length) % _deferredBootstrapTrace.Length;
+			for (var i = 0; i < _deferredBootstrapTraceCount; i++)
+			{
+				pending[i] = _deferredBootstrapTrace[(readIndex + i) % _deferredBootstrapTrace.Length];
+			}
+
+			_deferredBootstrapTraceCount = 0;
+		}
+
+		foreach (var entry in pending)
+		{
+			var symbolText = "<unreadable>";
+			if (TryReadAsciiZ(entry.SymbolPointer, 256, out var sym))
+			{
+				symbolText = sym;
+			}
+
+			Console.Error.WriteLine(
+				$"[LOADER][TRACE] bootstrap_call#{entry.DispatchIndex}: op=0x{entry.Op:X16} " +
+				$"sym_ptr=0x{entry.SymbolPointer:X16} sym='{symbolText}' " +
+				$"out_ptr=0x{entry.OutputPointer:X16} ret=0x{entry.ReturnRip:X16}");
+		}
+	}
+
 	private void DumpRecentImportTrace()
 	{
 		if (_recentImportTraceCount == 0)
@@ -170,14 +235,15 @@ public sealed partial class DirectExecutionBackend
 			ulong callRip = returnRip + (ulong)i;
 			ulong target = unchecked((ulong)((long)(callRip + 5) + rel32));
 			Log.Debug($"Import#{dispatchIndex} near-call @{callRip:X16}: target=0x{target:X16}");
-			for (int importIndex = 0; importIndex < _importEntries.Length; importIndex++)
+			var importEntries = _importEntries;
+			for (int importIndex = 0; importIndex < importEntries.Length; importIndex++)
 			{
-				if (_importEntries[importIndex].Address != target)
+				if (importEntries[importIndex].Address != target)
 				{
 					continue;
 				}
 
-				string nid = _importEntries[importIndex].Nid;
+				string nid = importEntries[importIndex].Nid;
 				if (_moduleManager.TryGetExport(nid, out var export))
 				{
 					Log.Debug(
@@ -204,14 +270,14 @@ public sealed partial class DirectExecutionBackend
 					{
 						Log.Debug(
 							$"Import#{dispatchIndex} near-call PLT slot: [0x{slot:X16}] = 0x{slotTarget:X16}");
-						for (int importIndex = 0; importIndex < _importEntries.Length; importIndex++)
+						for (int importIndex = 0; importIndex < importEntries.Length; importIndex++)
 						{
-							if (_importEntries[importIndex].Address != slotTarget)
+							if (importEntries[importIndex].Address != slotTarget)
 							{
 								continue;
 							}
 
-							string nid = _importEntries[importIndex].Nid;
+							string nid = importEntries[importIndex].Nid;
 							if (_moduleManager.TryGetExport(nid, out var export))
 							{
 								Log.Debug(

src/SharpEmu.Core/Cpu/Native/DirectExecutionBackend.Imports.cs

@@ -8,6 +8,7 @@ using System.Linq;
 using System.Runtime.InteropServices;
 using System.Threading;
 using SharpEmu.Core.Cpu;
+using SharpEmu.Core.Loader;
 using SharpEmu.HLE;
 
 namespace SharpEmu.Core.Cpu.Native;
@@ -110,12 +111,13 @@ public sealed partial class DirectExecutionBackend
 			LastError = "Import dispatch called without active CPU context";
 			return 18446744071562199298uL;
 		}
-		if ((uint)importIndex >= (uint)_importEntries.Length)
+		var importEntries = _importEntries;
+		if ((uint)importIndex >= (uint)importEntries.Length)
 		{
 			LastError = $"Import dispatch index out of range: {importIndex}";
 			return 18446744071562199042uL;
 		}
-		ImportStubEntry importStubEntry = _importEntries[importIndex];
+		ImportStubEntry importStubEntry = importEntries[importIndex];
 		int num2 = Volatile.Read(in _rawSentinelRecoveries);
 		if (num2 != _lastReportedRawSentinelRecoveries)
 		{
@@ -159,6 +161,14 @@ public sealed partial class DirectExecutionBackend
 				*(ulong*)(xmmSlot + 8));
 		}
 		cpuContext[CpuRegister.Rsp] = (ulong)argPackPtr + 96uL;
+		if (string.Equals(importStubEntry.Nid, RuntimeStubNids.BootstrapBridge, StringComparison.Ordinal))
+		{
+			NormalizeKernelDynlibDlsymArguments(cpuContext, out _, out _);
+			*(ulong*)argPackPtr = cpuContext[CpuRegister.Rdi];
+			*(ulong*)(argPackPtr + 8) = cpuContext[CpuRegister.Rsi];
+			*(ulong*)(argPackPtr + 16) = cpuContext[CpuRegister.Rdx];
+		}
+
 		ulong value = cpuContext[CpuRegister.Rdi];
 		ulong value2 = cpuContext[CpuRegister.Rsi];
 		ulong num3 = cpuContext[CpuRegister.Rdx];
@@ -209,16 +219,6 @@ public sealed partial class DirectExecutionBackend
 			TraceGuestContext(
 				$"import dispatch={num} nid={importStubEntry.Nid} ret=0x{num7:X16} managed={Environment.CurrentManagedThreadId} guest=0x{GuestThreadExecution.CurrentGuestThreadHandle:X16} fiber=0x{GuestThreadExecution.CurrentFiberAddress:X16} active={HasActiveExecutionThread}");
 		}
-		if (_logBootstrap && string.Equals(importStubEntry.Nid, RuntimeStubNids.BootstrapBridge, StringComparison.Ordinal))
-		{
-			string symbolText = "<unreadable>";
-			if (TryReadAsciiZ(value2, 256, out var sym))
-			{
-				symbolText = sym;
-			}
-			Console.Error.WriteLine(
-				$"[LOADER][TRACE] bootstrap_call#{num}: op=0x{value:X16} sym_ptr=0x{value2:X16} sym='{symbolText}' out_ptr=0x{num3:X16} ret=0x{num7:X16}");
-		}
 		if (!isGuestWorker &&
 			!ActiveForcedGuestExit &&
 			ShouldForceGuestExitOnImportLoop(importStubEntry.Nid, num7, num, value, value2) &&
@@ -383,6 +383,11 @@ public sealed partial class DirectExecutionBackend
 			{
 				if (string.Equals(importStubEntry.Nid, RuntimeStubNids.BootstrapBridge, StringComparison.Ordinal))
 				{
+					if (_logBootstrap)
+					{
+						RecordDeferredBootstrapTrace(num, value, value2, num3, num7);
+					}
+
 					orbisGen2Result = DispatchBootstrapBridge();
 				}
 				else if (string.Equals(importStubEntry.Nid, RuntimeStubNids.KernelDynlibDlsym, StringComparison.Ordinal) ||
@@ -545,6 +550,7 @@ public sealed partial class DirectExecutionBackend
 			cpuContext.GetXmmRegister(0, out var returnXmm0Low, out var returnXmm0High);
 			*(ulong*)(argPackPtr - 0x80) = returnXmm0Low;
 			*(ulong*)(argPackPtr - 0x80 + 8) = returnXmm0High;
+			DrainDeferredBootstrapTraces();
 			return cpuContext[CpuRegister.Rax];
 		}
 		catch (Exception ex)
@@ -553,6 +559,7 @@ public sealed partial class DirectExecutionBackend
 			Console.Error.WriteLine($"[LOADER][ERROR] {LastError}");
 			Console.Error.WriteLine($"[LOADER][ERROR] {ex.StackTrace}");
 			cpuContext[CpuRegister.Rax] = 18446744071562199298uL;
+			DrainDeferredBootstrapTraces();
 			return 18446744071562199298uL;
 		}
 	}
@@ -1311,30 +1318,485 @@ public sealed partial class DirectExecutionBackend
 		{
 			return OrbisGen2Result.ORBIS_GEN2_ERROR_INVALID_ARGUMENT;
 		}
-		ulong symbolNameAddress = cpuContext[CpuRegister.Rsi];
-		ulong outputAddress = cpuContext[CpuRegister.Rdx];
-		if (!TryReadAsciiZ(symbolNameAddress, 512, out var symbolName))
+
+		NormalizeKernelDynlibDlsymArguments(cpuContext, out var symbolNameAddress, out var outputAddress);
+		try
 		{
-			cpuContext[CpuRegister.Rax] = 18446744073709551615uL;
-			return OrbisGen2Result.ORBIS_GEN2_OK;
+			if (!TryReadAsciiZ(symbolNameAddress, 512, out var symbolName) ||
+				!TryResolveDlsymGuestAddress(symbolName, out var resolvedAddress) ||
+				outputAddress == 0 ||
+				!TryWriteUInt64Compat(outputAddress, resolvedAddress))
+			{
+				return CompleteKernelDynlibDlsymFailure(cpuContext, outputAddress);
+			}
 		}
-		if (!TryResolveRuntimeSymbolAddress(symbolName, out var resolvedAddress) &&
-			!TryResolveRuntimeSymbolAlias(symbolName, out resolvedAddress))
+		catch
 		{
-			Console.Error.WriteLine(
-				$"[LOADER][WARN] sceKernelDlsym failed: handle=0x{cpuContext[CpuRegister.Rdi]:X} symbol='{symbolName}'");
-			cpuContext[CpuRegister.Rax] = 18446744073709551615uL;
-			return OrbisGen2Result.ORBIS_GEN2_OK;
-		}
-		if (outputAddress == 0L || !TryWriteUInt64Compat(outputAddress, resolvedAddress))
-		{
-			cpuContext[CpuRegister.Rax] = 18446744073709551615uL;
-			return OrbisGen2Result.ORBIS_GEN2_OK;
+			return CompleteKernelDynlibDlsymFailure(cpuContext, outputAddress);
 		}
+
 		cpuContext[CpuRegister.Rax] = 0uL;
 		return OrbisGen2Result.ORBIS_GEN2_OK;
 	}
 
+	private static void NormalizeKernelDynlibDlsymArguments(
+		CpuContext cpuContext,
+		out ulong symbolNameAddress,
+		out ulong outputAddress)
+	{
+		var handle = cpuContext[CpuRegister.Rdi];
+		symbolNameAddress = cpuContext[CpuRegister.Rsi];
+		outputAddress = cpuContext[CpuRegister.Rdx];
+
+		// Standalone bootstrap loaders sometimes call through the bridge with
+		// (symbol_ptr, handle, out) while sceKernelDlsym is (handle, symbol_ptr, out).
+		// Heuristic only: valid when RSI looks like a small handle and RDI is a guest pointer.
+		if (symbolNameAddress < 0x10000 &&
+			IsPlausibleDynlibSymbolPointer(handle))
+		{
+			symbolNameAddress = handle;
+			handle = cpuContext[CpuRegister.Rsi];
+			cpuContext[CpuRegister.Rdi] = handle;
+			cpuContext[CpuRegister.Rsi] = symbolNameAddress;
+		}
+	}
+
+	private static bool IsPlausibleDynlibSymbolPointer(ulong address)
+	{
+		return address >= 0x10000 && address < 0x0000_8000_0000_0000UL;
+	}
+
+	private OrbisGen2Result CompleteKernelDynlibDlsymFailure(CpuContext cpuContext, ulong outputAddress)
+	{
+		if (outputAddress != 0)
+		{
+			_ = TryWriteUInt64Compat(outputAddress, 0);
+		}
+
+		cpuContext[CpuRegister.Rax] = ulong.MaxValue;
+		return OrbisGen2Result.ORBIS_GEN2_OK;
+	}
+
+	private void ResetLazyDlsymStubState()
+	{
+		lock (_lazyDlsymStubGate)
+		{
+			_lazyDlsymStubCache.Clear();
+			_lazyImportStubPoolMapped = false;
+			_lazyImportStubPoolBase = 0;
+			_lazyImportStubNextSlot = 0;
+			_lazyImportStubPoolLimit = 0;
+		}
+	}
+
+	private bool TryResolveDlsymGuestAddress(string symbolName, out ulong guestAddress)
+	{
+		guestAddress = 0;
+		if (string.IsNullOrWhiteSpace(symbolName))
+		{
+			return false;
+		}
+
+		// Tier 0: ELF runtime symbols and aliases.
+		if (TryResolveRuntimeSymbolAddress(symbolName, out guestAddress) ||
+			TryResolveRuntimeSymbolAlias(symbolName, out guestAddress))
+		{
+			return true;
+		}
+
+		// Tier 1: existing import stub entries (duplicate prevention).
+		if (TryFindImportStubGuestAddress(symbolName, out guestAddress))
+		{
+			return true;
+		}
+
+		var hasAerolibSymbol = Aerolib.Instance.TryGetByExportName(symbolName, out var hleSymbol);
+		if (hasAerolibSymbol)
+		{
+			if (HleDataSymbols.TryGetAddress(hleSymbol.Nid, out _))
+			{
+				return false;
+			}
+
+			if (TryResolveRuntimeSymbolAddress(hleSymbol.Nid, out guestAddress) ||
+				TryResolveRuntimeSymbolAddress(hleSymbol.ExportName, out guestAddress) ||
+				TryFindImportStubGuestAddress(hleSymbol.Nid, out guestAddress) ||
+				TryFindImportStubGuestAddress(hleSymbol.ExportName, out guestAddress))
+			{
+				return true;
+			}
+		}
+		else if (Aerolib.Instance.TryGetByNid(symbolName, out hleSymbol))
+		{
+			if (HleDataSymbols.TryGetAddress(hleSymbol.Nid, out _))
+			{
+				return false;
+			}
+
+			if (TryFindImportStubGuestAddress(hleSymbol.Nid, out guestAddress) ||
+				TryFindImportStubGuestAddress(hleSymbol.ExportName, out guestAddress))
+			{
+				return true;
+			}
+
+			hasAerolibSymbol = true;
+		}
+
+		// Tier 3: lazy materialization for callable HLE symbols missing from ELF imports.
+		if (!TryResolveLazyDispatchTarget(symbolName, hasAerolibSymbol, in hleSymbol, out var dispatchNid, out var export))
+		{
+			return false;
+		}
+
+		return TryGetOrCreateLazyImportStub(
+			dispatchNid,
+			symbolName,
+			hasAerolibSymbol ? hleSymbol : null,
+			export,
+			out guestAddress);
+	}
+
+	private bool TryFindImportStubGuestAddress(string identifier, out ulong guestAddress)
+	{
+		guestAddress = 0;
+		if (string.IsNullOrWhiteSpace(identifier))
+		{
+			return false;
+		}
+
+		var importEntries = _importEntries;
+		for (var i = 0; i < importEntries.Length; i++)
+		{
+			var entry = importEntries[i];
+			if (!ImportStubEntryMatchesIdentifier(entry, identifier))
+			{
+				continue;
+			}
+
+			if (entry.Address >= 0x10000)
+			{
+				guestAddress = entry.Address;
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	private static bool ImportStubEntryMatchesIdentifier(in ImportStubEntry entry, string identifier)
+	{
+		if (string.Equals(entry.Nid, identifier, StringComparison.Ordinal))
+		{
+			return true;
+		}
+
+		if (entry.Export is not { } export)
+		{
+			return false;
+		}
+
+		return string.Equals(export.Name, identifier, StringComparison.Ordinal) ||
+			string.Equals(export.Nid, identifier, StringComparison.Ordinal);
+	}
+
+	private static bool IsKernelDynlibDlsymIdentifier(string identifier)
+	{
+		return string.Equals(identifier, "sceKernelDlsym", StringComparison.Ordinal) ||
+			string.Equals(identifier, KernelDynlibDlsymAerolibNid, StringComparison.Ordinal) ||
+			string.Equals(identifier, RuntimeStubNids.KernelDynlibDlsym, StringComparison.Ordinal);
+	}
+
+	private bool TryResolveLazyDispatchTarget(
+		string symbolName,
+		bool hasAerolibSymbol,
+		in SysAbiSymbol hleSymbol,
+		out string dispatchNid,
+		out ExportedFunction? export)
+	{
+		export = null;
+		dispatchNid = string.Empty;
+
+		if (IsKernelDynlibDlsymIdentifier(symbolName))
+		{
+			dispatchNid = KernelDynlibDlsymAerolibNid;
+			_ = _moduleManager.TryGetExport(dispatchNid, out export);
+			return true;
+		}
+
+		if (!hasAerolibSymbol)
+		{
+			return false;
+		}
+
+		if (HleDataSymbols.TryGetAddress(hleSymbol.Nid, out _))
+		{
+			return false;
+		}
+
+		if (_moduleManager.TryGetExport(hleSymbol.Nid, out export))
+		{
+			dispatchNid = hleSymbol.Nid;
+			return true;
+		}
+
+		return false;
+	}
+
+	private bool TryGetOrCreateLazyImportStub(
+		string dispatchNid,
+		string symbolName,
+		SysAbiSymbol? hleSymbol,
+		ExportedFunction? export,
+		out ulong guestAddress)
+	{
+		guestAddress = 0;
+		if (string.IsNullOrWhiteSpace(dispatchNid))
+		{
+			return false;
+		}
+
+		lock (_lazyDlsymStubGate)
+		{
+			if (TryGetCachedLazyDlsymAddress(dispatchNid, symbolName, out guestAddress))
+			{
+				return true;
+			}
+
+			if (!EnsureLazyImportStubPoolMapped())
+			{
+				LogLazyImportStubMaterializationFailure(
+					"import stub region unresolved",
+					dispatchNid,
+					symbolName);
+				return false;
+			}
+
+			if (!TryAllocateLazyImportStubSlot(out guestAddress))
+			{
+				LogLazyImportStubMaterializationFailure(
+					"lazy import stub pool exhausted",
+					dispatchNid,
+					symbolName);
+				return false;
+			}
+
+			var previousEntries = _importEntries;
+			var importIndex = previousEntries.Length;
+			var newEntries = new ImportStubEntry[importIndex + 1];
+			if (importIndex > 0)
+			{
+				Array.Copy(previousEntries, newEntries, importIndex);
+			}
+
+			newEntries[importIndex] = new ImportStubEntry(guestAddress, dispatchNid, export);
+
+			var hostTrampoline = CreateImportHandlerTrampoline(importIndex);
+			if (hostTrampoline == 0 ||
+				!PatchImportStub((nint)(long)guestAddress, hostTrampoline))
+			{
+				guestAddress = 0;
+				LogLazyImportStubMaterializationFailure(
+					"failed to patch lazy import stub trampoline",
+					dispatchNid,
+					symbolName);
+				return false;
+			}
+
+			_importEntries = newEntries;
+
+			RegisterDlsymRuntimeSymbolKeys(symbolName, dispatchNid, hleSymbol, guestAddress);
+			return true;
+		}
+	}
+
+	private bool TryGetCachedLazyDlsymAddress(string dispatchNid, string symbolName, out ulong guestAddress)
+	{
+		if (_lazyDlsymStubCache.TryGetValue(dispatchNid, out guestAddress) ||
+			_lazyDlsymStubCache.TryGetValue(symbolName, out guestAddress))
+		{
+			return guestAddress >= 0x10000;
+		}
+
+		return false;
+	}
+
+	private void RegisterDlsymRuntimeSymbolKeys(
+		string symbolName,
+		string dispatchNid,
+		SysAbiSymbol? hleSymbol,
+		ulong guestAddress)
+	{
+		RegisterDlsymRuntimeSymbolKey(symbolName, guestAddress);
+		RegisterDlsymRuntimeSymbolKey(dispatchNid, guestAddress);
+
+		if (IsKernelDynlibDlsymIdentifier(symbolName) || IsKernelDynlibDlsymIdentifier(dispatchNid))
+		{
+			RegisterDlsymRuntimeSymbolKey(RuntimeStubNids.KernelDynlibDlsym, guestAddress);
+			RegisterDlsymRuntimeSymbolKey(KernelDynlibDlsymAerolibNid, guestAddress);
+			RegisterDlsymRuntimeSymbolKey("sceKernelDlsym", guestAddress);
+		}
+
+		if (hleSymbol.HasValue)
+		{
+			RegisterDlsymRuntimeSymbolKey(hleSymbol.Value.Nid, guestAddress);
+			RegisterDlsymRuntimeSymbolKey(hleSymbol.Value.ExportName, guestAddress);
+		}
+	}
+
+	private void RegisterDlsymRuntimeSymbolKey(string key, ulong guestAddress)
+	{
+		if (string.IsNullOrWhiteSpace(key) || !IsRuntimeSymbolAddressUsable(guestAddress))
+		{
+			return;
+		}
+
+		_runtimeSymbolsByName[key] = guestAddress;
+		_lazyDlsymStubCache[key] = guestAddress;
+	}
+
+	private void LogLazyImportStubMaterializationFailure(string reason, string dispatchNid, string symbolName)
+	{
+		Console.Error.WriteLine(
+			$"[LOADER][WARN] Lazy import stub materialization failed ({reason}): " +
+			$"nid={dispatchNid} symbol='{symbolName}'");
+	}
+
+	private unsafe bool TryResolveImportStubRegionBounds(
+		ImportStubEntry[] importEntries,
+		out ulong regionBase,
+		out ulong regionLimit)
+	{
+		regionBase = 0;
+		regionLimit = 0;
+
+		for (var candidateIndex = 0; candidateIndex < 64; candidateIndex++)
+		{
+			var candidateBase = ImportStubRegionCanonicalBase -
+				(ulong)candidateIndex * ImportStubRegionAddressStride;
+			if (VirtualQuery((void*)candidateBase, out var memoryInfo, (nuint)sizeof(MEMORY_BASIC_INFORMATION64)) == 0 ||
+				memoryInfo.RegionSize == 0 ||
+				memoryInfo.State != 4096)
+			{
+				continue;
+			}
+
+			var candidateLimit = candidateBase + memoryInfo.RegionSize;
+			var hasStub = false;
+			for (var i = 0; i < importEntries.Length; i++)
+			{
+				var entryAddress = importEntries[i].Address;
+				if (entryAddress < candidateBase || entryAddress >= candidateLimit)
+				{
+					continue;
+				}
+
+				if ((entryAddress - candidateBase) % LazyImportStubSlotSize != 0)
+				{
+					continue;
+				}
+
+				hasStub = true;
+				break;
+			}
+
+			if (!hasStub)
+			{
+				continue;
+			}
+
+			regionBase = candidateBase;
+			regionLimit = candidateLimit;
+			return true;
+		}
+
+		ulong maxStubEnd = 0;
+		for (var i = 0; i < importEntries.Length; i++)
+		{
+			var entryAddress = importEntries[i].Address;
+			if (entryAddress < ImportStubRegionCanonicalBase)
+			{
+				continue;
+			}
+
+			if ((entryAddress - ImportStubRegionCanonicalBase) % LazyImportStubSlotSize != 0)
+			{
+				continue;
+			}
+
+			var entryEnd = entryAddress + LazyImportStubSlotSize;
+			if (entryEnd > maxStubEnd)
+			{
+				maxStubEnd = entryEnd;
+				regionBase = ImportStubRegionCanonicalBase;
+			}
+		}
+
+		if (regionBase == 0 || maxStubEnd <= regionBase)
+		{
+			return false;
+		}
+
+		var spanBytes = maxStubEnd - regionBase;
+		regionLimit = regionBase + AlignUp(spanBytes, ImportStubRegionPageSize);
+		return regionLimit > regionBase;
+	}
+
+	private bool EnsureLazyImportStubPoolMapped()
+	{
+		if (_lazyImportStubPoolMapped && _lazyImportStubPoolBase != 0)
+		{
+			return true;
+		}
+
+		var importEntries = _importEntries;
+		if (!TryResolveImportStubRegionBounds(importEntries, out var importStubRegionBase, out var importStubRegionLimit))
+		{
+			return false;
+		}
+
+		ulong nextSlot = importStubRegionBase;
+		for (var i = 0; i < importEntries.Length; i++)
+		{
+			var entryAddress = importEntries[i].Address;
+			if (entryAddress < importStubRegionBase || entryAddress >= importStubRegionLimit)
+			{
+				continue;
+			}
+
+			var entryEnd = entryAddress + LazyImportStubSlotSize;
+			if (entryEnd > nextSlot)
+			{
+				nextSlot = entryEnd;
+			}
+		}
+
+		if (nextSlot >= importStubRegionLimit)
+		{
+			return false;
+		}
+
+		_lazyImportStubPoolBase = importStubRegionBase;
+		_lazyImportStubNextSlot = nextSlot;
+		_lazyImportStubPoolLimit = importStubRegionLimit;
+		_lazyImportStubPoolMapped = true;
+		return true;
+	}
+
+	private bool TryAllocateLazyImportStubSlot(out ulong guestAddress)
+	{
+		guestAddress = 0;
+		if (!_lazyImportStubPoolMapped ||
+			_lazyImportStubNextSlot < _lazyImportStubPoolBase ||
+			_lazyImportStubNextSlot + LazyImportStubSlotSize > _lazyImportStubPoolLimit)
+		{
+			return false;
+		}
+
+		guestAddress = _lazyImportStubNextSlot;
+		_lazyImportStubNextSlot += LazyImportStubSlotSize;
+		return true;
+	}
+
 	private bool TryResolveRuntimeSymbolAlias(string symbolName, out ulong address)
 	{
 		address = 0;
@@ -1399,29 +1861,20 @@ public sealed partial class DirectExecutionBackend
 			return OrbisGen2Result.ORBIS_GEN2_ERROR_INVALID_ARGUMENT;
 		}
 
-		ulong bridgeHandle = cpuContext[CpuRegister.Rdi];
-		ulong symbolNameAddress = cpuContext[CpuRegister.Rsi];
 		ulong outputAddress = cpuContext[CpuRegister.Rdx];
-		_ = TryReadAsciiZ(symbolNameAddress, 512, out var symbolName);
-
-		OrbisGen2Result result = DispatchKernelDynlibDlsym();
-		if (result != OrbisGen2Result.ORBIS_GEN2_OK)
+		try
 		{
-			return result;
+			OrbisGen2Result result = DispatchKernelDynlibDlsym();
+			if (result != OrbisGen2Result.ORBIS_GEN2_OK)
+			{
+				return result;
+			}
 		}
-		if (_logBootstrap)
+		catch
 		{
-			Console.Error.WriteLine(
-				$"[LOADER][TRACE] bootstrap_dispatch: handle=0x{bridgeHandle:X16} symbol='{symbolName}' out=0x{outputAddress:X16} rax=0x{cpuContext[CpuRegister.Rax]:X16}");
+			return CompleteKernelDynlibDlsymFailure(cpuContext, outputAddress);
 		}
 
-		if (cpuContext[CpuRegister.Rax] == 0uL)
-		{
-			return OrbisGen2Result.ORBIS_GEN2_OK;
-		}
-
-		Console.Error.WriteLine(
-			$"[LOADER][WARN] bootstrap_bridge unresolved: handle=0x{bridgeHandle:X} symbol='{symbolName}' out=0x{outputAddress:X16}");
 		return OrbisGen2Result.ORBIS_GEN2_OK;
 	}
 
@@ -1462,6 +1915,7 @@ public sealed partial class DirectExecutionBackend
 		{
 			return false;
 		}
+
 		List<byte> list = new List<byte>(Math.Min(maxLength, 256));
 		Span<byte> destination = stackalloc byte[1];
 		for (int i = 0; i < maxLength; i++)

src/SharpEmu.Core/Cpu/Native/DirectExecutionBackend.cs

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
@@ -48,6 +49,13 @@ public sealed unsafe partial class DirectExecutionBackend : INativeCpuBackend, I
 		ulong Arg1,
 		ulong Arg2);
 
+	private readonly record struct DeferredBootstrapTraceEntry(
+		long DispatchIndex,
+		ulong Op,
+		ulong SymbolPointer,
+		ulong OutputPointer,
+		ulong ReturnRip);
+
 #pragma warning disable CS0649
 	private struct EXCEPTION_POINTERS
 	{
@@ -232,7 +240,31 @@ public sealed unsafe partial class DirectExecutionBackend : INativeCpuBackend, I
 
 	private KeyValuePair<string, ulong>[] _runtimeSymbolsByAddress = Array.Empty<KeyValuePair<string, ulong>>();
 
-	private readonly Dictionary<string, ulong> _runtimeSymbolsByName = new Dictionary<string, ulong>(StringComparer.Ordinal);
+	private readonly ConcurrentDictionary<string, ulong> _runtimeSymbolsByName =
+		new(StringComparer.Ordinal);
+
+	// Keep in sync with SelfLoader import-stub mapping constants.
+	private const ulong ImportStubRegionCanonicalBase = 0x0000_7000_0000_0000UL;
+
+	private const ulong ImportStubRegionAddressStride = 0x0000_0000_0100_0000UL;
+
+	private const ulong LazyImportStubSlotSize = 0x10;
+
+	private const ulong ImportStubRegionPageSize = 0x1000UL;
+
+	private const string KernelDynlibDlsymAerolibNid = "LwG8g3niqwA";
+
+	private readonly object _lazyDlsymStubGate = new();
+
+	private readonly Dictionary<string, ulong> _lazyDlsymStubCache = new(StringComparer.Ordinal);
+
+	private ulong _lazyImportStubPoolBase;
+
+	private ulong _lazyImportStubNextSlot;
+
+	private ulong _lazyImportStubPoolLimit;
+
+	private bool _lazyImportStubPoolMapped;
 
 	private readonly RecentImportTraceEntry[] _recentImportTrace = new RecentImportTraceEntry[64];
 
@@ -240,6 +272,14 @@ public sealed unsafe partial class DirectExecutionBackend : INativeCpuBackend, I
 
 	private int _recentImportTraceWriteIndex;
 
+	private readonly DeferredBootstrapTraceEntry[] _deferredBootstrapTrace = new DeferredBootstrapTraceEntry[32];
+
+	private int _deferredBootstrapTraceCount;
+
+	private int _deferredBootstrapTraceWriteIndex;
+
+	private readonly object _deferredBootstrapTraceGate = new();
+
 	private readonly string[] _distinctImportNidHistory = new string[128];
 
 	private int _distinctImportNidHistoryCount;
@@ -855,8 +895,14 @@ public sealed unsafe partial class DirectExecutionBackend : INativeCpuBackend, I
 		result = OrbisGen2Result.ORBIS_GEN2_OK;
 		LastError = null;
 		InitializeRuntimeSymbolIndex(runtimeSymbols);
+		ResetLazyDlsymStubState();
 		_recentImportTraceCount = 0;
 		_recentImportTraceWriteIndex = 0;
+		lock (_deferredBootstrapTraceGate)
+		{
+			_deferredBootstrapTraceCount = 0;
+			_deferredBootstrapTraceWriteIndex = 0;
+		}
 		_distinctImportNidHistoryCount = 0;
 		_distinctImportNidHistoryWriteIndex = 0;
 		_lastDistinctImportNid = string.Empty;
@@ -930,6 +976,7 @@ public sealed unsafe partial class DirectExecutionBackend : INativeCpuBackend, I
 		}
 		finally
 		{
+			DrainDeferredBootstrapTraces();
 			GuestThreadExecution.Scheduler = previousGuestThreadScheduler;
 			Console.Error.WriteLine("[LOADER][INFO] === Execute END (LastError: " + (LastError ?? "null") + ") ===");
 		}
@@ -4456,13 +4503,14 @@ public sealed unsafe partial class DirectExecutionBackend : INativeCpuBackend, I
 			ulong rsp = cpuContext[CpuRegister.Rsp];
 			Console.Error.WriteLine($"[LOADER][ERROR] Stall snapshot: rip=0x{cpuContext.Rip:X16} rsp=0x{rsp:X16} rbp=0x{cpuContext[CpuRegister.Rbp]:X16} rax=0x{cpuContext[CpuRegister.Rax]:X16} rbx=0x{cpuContext[CpuRegister.Rbx]:X16} rcx=0x{cpuContext[CpuRegister.Rcx]:X16} rdx=0x{cpuContext[CpuRegister.Rdx]:X16} rsi=0x{cpuContext[CpuRegister.Rsi]:X16} rdi=0x{cpuContext[CpuRegister.Rdi]:X16}");
 			ulong num = cpuContext.Rip & 0xFFFFFFFFFFFFFFF0uL;
-			for (int i = 0; i < _importEntries.Length; i++)
+			var importEntries = _importEntries;
+			for (int i = 0; i < importEntries.Length; i++)
 			{
-				if (_importEntries[i].Address != num)
+				if (importEntries[i].Address != num)
 				{
 					continue;
 				}
-				string text = _importEntries[i].Nid;
+				string text = importEntries[i].Nid;
 				if (_moduleManager.TryGetExport(text, out ExportedFunction export))
 				{
 					Console.Error.WriteLine($"[LOADER][ERROR] Stall import-stub: rip=0x{num:X16} nid={text} -> {export.LibraryName}:{export.Name}");
@@ -4653,6 +4701,7 @@ public sealed unsafe partial class DirectExecutionBackend : INativeCpuBackend, I
 		ClearImportHandlerTrampolines();
 		_importEntries = Array.Empty<ImportStubEntry>();
 		_runtimeSymbolsByName.Clear();
+		ResetLazyDlsymStubState();
 		_importNidHashCache.Clear();
 		StopStallWatchdog();
 		if (_exceptionHandler != 0)