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There are two primary ways to configure runtime behavior: CoreCLR hosts can pass in key-value string pairs during runtime initialization, or users can set special variables in the environment or registry. Today, the set of configuration options that can be set via the former method is relatively small, but moving forward, we expect to add more options there. Each set of options is described below.

Host Configuration Knobs

These can be passed in by a host during initialization. Note that the values are all passed in as strings, so if the type is boolean, the value would be the string "true" or "false", and if it's a numeric value, it would be in the form "123".

Name Description Type
System.GC.Concurrent Enable concurrent GC boolean
System.GC.Server Enable server GC boolean
System.GC.RetainVM Put segments that should be deleted on a standby list for future use instead of releasing them back to the OS boolean
System.Runtime.TieredCompilation Enable tiered compilation boolean
System.Threading.ThreadPool.MinThreads Override MinThreads for the ThreadPool worker pool numeric
System.Threading.ThreadPool.MaxThreads Override MaxThreads for the ThreadPool worker pool numeric

Environment/Registry Configuration Knobs

This table was machine-generated using clr-configuration-knobs.csx script from repository commit 79aadb8 on 6/12/2018. It might be out of date. To generate latest documentation run {dotnet} csi clr-configuration-knobs.csx from this file directory.

When using these configurations from environment variables, the variables need to have the COMPlus_ prefix in their names. e.g. To set DumpJittedMethods to 1, add the environment variable COMPlus_DumpJittedMethods=1.

See also Setting configuration variables for more information.

Tables

  1. AppDomain Configuration Knobs
  2. ARM Configuration Knobs
  3. Assembly Loader Configuration Knobs
  4. Conditional breakpoints Configuration Knobs
  5. Debugger Configuration Knobs
  6. Diagnostics (internal general-purpose) Configuration Knobs
  7. Exception Handling Configuration Knobs
  8. Garbage collector Configuration Knobs
  9. GDBJIT Configuration Knobs
  10. IBC Configuration Knobs
  11. Interop Configuration Knobs
  12. Interpreter Configuration Knobs
  13. JIT Configuration Knobs
  14. JIT Hardware Intrinsics Configuration Knobs
  15. Jit Pitching Configuration Knobs
  16. Loader Configuration Knobs
  17. Loader heap Configuration Knobs
  18. Log Configuration Knobs
  19. MetaData Configuration Knobs
  20. Native Binder Configuration Knobs
  21. NGEN Configuration Knobs
  22. Performance Configuration Knobs
  23. Profiling API / ETW Configuration Knobs
  24. Spinning heuristics Configuration Knobs
  25. Stress Configuration Knobs
  26. Thread (miscellaneous) Configuration Knobs
  27. Thread Suspend Configuration Knobs
  28. Threadpool Configuration Knobs
  29. Tiered Compilation Configuration Knobs
  30. TypeLoader Configuration Knobs
  31. Uncategorized Configuration Knobs
  32. Virtual call stubs Configuration Knobs
  33. Watson Configuration Knobs
  34. Zap Configuration Knobs

AppDomain Configuration Knobs

Name Description Type Class Default Value Flags
ADBreakOnCannotUnload Used to troubleshoot failures to unload appdomain (e.g. someone sitting in unmanged code). In some cases by the time we throw the appropriate exception the thread has moved from the offending call. This setting allows in an instrumented build to stop exactly at the right moment. DWORD INTERNAL 0
AddRejitNops Control for the profiler rejit feature infrastructure DWORD UNSUPPORTED
ADDumpSB Not used DWORD INTERNAL 0
ADForceSB Forces sync block creation for all objects DWORD INTERNAL 0
ADLogMemory Superseded by test hooks DWORD INTERNAL 0
ADTakeDHSnapShot Superseded by test hooks DWORD INTERNAL 0
ADTakeSnapShot Superseded by test hooks DWORD INTERNAL 0
ADULazyMemoryRelease On by default. Turned off in cases when people try to catch memory leaks, in which case AD unload should be immediately followed by GC) DWORD EXTERNAL 1
ADURetryCount Controls timeout of AD unload. Used for workarounds when machine is too slow, there are network issues etc. DWORD EXTERNAL
EnableFullDebug Heavy-weight checking for AD boundary violations (AD leaks) DWORD INTERNAL
FinalizeOnShutdown When enabled, on shutdown, blocks all user threads and calls finalizers for all finalizable objects, including live objects DWORD EXTERNAL DEFAULT_FinalizeOnShutdown

ARM Configuration Knobs

Name Description Type Class Default Value Flags
ARMEnabled Set it to 1 to enable ARM DWORD UNSUPPORTED (DWORD)0

Assembly Loader Configuration Knobs

Name Description Type Class Default Value Flags
designerNamespaceResolution Set it to 1 to enable DesignerNamespaceResolve event for WinRT types DWORD EXTERNAL FALSE IgnoreEnv | IgnoreHKLM | IgnoreHKCU | FavorConfigFile
GetAssemblyIfLoadedIgnoreRidMap Used to force loader to ignore assemblies cached in the rid-map DWORD INTERNAL 0 REGUTIL_default

Conditional breakpoints Configuration Knobs

Name Description Type Class Default Value Flags
BreakOnBadExit DWORD UNSUPPORTED 0 REGUTIL_default
BreakOnClassBuild Very useful for debugging class layout code. STRING INTERNAL
BreakOnClassLoad Very useful for debugging class loading code. STRING INTERNAL
BreakOnComToClrNativeInfoInit Throws an assert when native information about a COM -> CLR call are about to be gathered. STRING INTERNAL
BreakOnDebugBreak Allows an assert in debug builds when a user break is hit DWORD INTERNAL 0 REGUTIL_default
BreakOnDILoad Allows an assert when the DI is loaded DWORD INTERNAL 0 REGUTIL_default
BreakOnDumpToken Breaks when using internal logging on a particular token value. DWORD INTERNAL 0xffffffff REGUTIL_default
BreakOnEELoad DWORD UNSUPPORTED 0 REGUTIL_default
BreakOnEEShutdown DWORD INTERNAL 0
BreakOnExceptionInGetThrowable DWORD INTERNAL 0 REGUTIL_default
BreakOnFinalizeTimeOut Triggers a debug break on the finalizer thread when it has exceeded the maximum wait time DWORD UNSUPPORTED 0
BreakOnFindMethod Breaks in findMethodInternal when it searches for the specified token. DWORD INTERNAL 0
BreakOnFirstPass DWORD INTERNAL 0 REGUTIL_default
BreakOnHR Debug.cpp, IfFailxxx use this macro to stop if hr matches DWORD INTERNAL 0 REGUTIL_default
BreakOnInstantiation Very useful for debugging generic class instantiation. STRING INTERNAL
BreakOnInteropStubSetup Throws an assert when marshaling stub for the given method is about to be built. STRING INTERNAL
BreakOnInteropVTableBuild Specifies a type name for which an assert should be thrown when building interop v-table. STRING INTERNAL REGUTIL_default
BreakOnMethodName Very useful for debugging method override placement code. STRING INTERNAL
BreakOnNGenRegistryAccessCount Breaks on the Nth' root store write DWORD UNSUPPORTED 0 REGUTIL_default
BreakOnNotify DWORD INTERNAL 0 REGUTIL_default
BreakOnRetailAssert Used for debugging "retail" asserts (fatal errors) DWORD INTERNAL 0 REGUTIL_default
BreakOnSecondPass DWORD INTERNAL 0 REGUTIL_default
BreakOnSO DWORD UNSUPPORTED 0 REGUTIL_default
BreakOnStructMarshalSetup Throws an assert when field marshalers for the given type with layout are about to be created. STRING INTERNAL
BreakOnUEF DWORD INTERNAL 0 REGUTIL_default
BreakOnUncaughtException DWORD INTERNAL 0 REGUTIL_default

Debugger Configuration Knobs

Name Description Type Class Default Value Flags
D::FCE Allows an assert when crawling the managed stack for an exception handler DWORD INTERNAL 0 REGUTIL_default
DbgAssertOnDebuggeeDebugBreak If non-zero causes the managed-only debugger to assert on unhandled breakpoints in the debuggee DWORD INTERNAL 0 REGUTIL_default
DbgBreakIfLocksUnavailable Allows an assert when the debugger can't take a lock DWORD INTERNAL 0 REGUTIL_default
DbgBreakOnErr Allows an assert when we get a failing hresult DWORD INTERNAL 0 REGUTIL_default
DbgBreakOnMapPatchToDJI Allows an assert when mapping a patch to an address DWORD INTERNAL 0 REGUTIL_default
DbgBreakOnRawInt3 Allows an assert for test coverage for debug break or other int3 breaks DWORD INTERNAL 0 REGUTIL_default
DbgBreakOnSendBreakpoint Allows an assert when sending a breakpoint to the right side DWORD INTERNAL 0 REGUTIL_default
DbgBreakOnSetIP Allows an assert when setting the IP DWORD INTERNAL 0 REGUTIL_default
DbgCheckInt3 Asserts if the debugger explicitly writes int3 instead of calling SetUnmanagedBreakpoint DWORD INTERNAL 0 REGUTIL_default
DbgDACAssertOnMismatch Allows an assert when the mscordacwks and mscorwks dll versions don't match DWORD INTERNAL
DbgDACEnableAssert Enables extra validity checking in DAC - assumes target isn't corrupt DWORD INTERNAL 0 REGUTIL_default
DbgDACSkipVerifyDlls Allows disabling the check to ensure mscordacwks and mscorwks dll versions match DWORD INTERNAL 0 REGUTIL_default
DbgDelayHelper Varies the wait in the helper thread startup for testing race between threads DWORD INTERNAL 0 REGUTIL_default
DbgDisableDynamicSymsCompat DWORD INTERNAL 0 REGUTIL_default
DbgDisableTargetConsistencyAsserts Allows explicitly testing with corrupt targets DWORD INTERNAL 0 REGUTIL_default
DbgDontResumeThreadsOnUnhandledException If non-zero, then don't try to unsuspend threads after continuing a 2nd-chance native exception DWORD UNSUPPORTED 0
DbgEnableMixedModeDebuggingInternalOnly DWORD INTERNAL 0 REGUTIL_default
DbgExtraThreads Allows extra unmanaged threads to run and throw debug events for stress testing DWORD INTERNAL 0 REGUTIL_default
DbgExtraThreadsCantStop Allows extra unmanaged threads in can't stop region to run and throw debug events for stress testing DWORD INTERNAL 0 REGUTIL_default
DbgExtraThreadsIB Allows extra in-band unmanaged threads to run and throw debug events for stress testing DWORD INTERNAL 0 REGUTIL_default
DbgExtraThreadsOOB Allows extra out of band unmanaged threads to run and throw debug events for stress testing DWORD INTERNAL 0 REGUTIL_default
DbgFaultInHandleIPCEvent Allows testing the unhandled event filter DWORD INTERNAL 0 REGUTIL_default
DbgInjectFEE Allows injecting a fatal execution error for testing Watson DWORD INTERNAL 0 REGUTIL_default
DbgLeakCheck Allows checking for leaked Cordb objects DWORD INTERNAL 0 REGUTIL_default
DbgNativeCodeBpBindsAcrossVersions If non-zero causes native breakpoints at offset 0 to bind in all tiered compilation versions of the given method DWORD INTERNAL 0 REGUTIL_default
DbgNo2ndChance Allows breaking on (and catching bogus) 2nd chance exceptions DWORD INTERNAL 0 REGUTIL_default
DbgNoDebugger Allows breaking if we don't want to lazily initialize the debugger DWORD INTERNAL 0 REGUTIL_default
DbgNoForceContinue Used to force a continue on longhorn DWORD UNSUPPORTED 1 REGUTIL_default
DbgNoOpenMDByFile Allows opening MD by memory for perf testing DWORD INTERNAL 0 REGUTIL_default
DbgOOBinFEEE Allows forcing oob breakpoints when a fatal error occurs DWORD INTERNAL 0
DbgPackShimPath CoreCLR path to dbgshim.dll - we are trying to figure out if we can remove this STRING EXTERNAL
DbgPingInterop Allows checking for deadlocks in interop debugging DWORD INTERNAL 0 REGUTIL_default
DbgRace Allows pausing for native debug events to get hijicked DWORD INTERNAL 0 REGUTIL_default
DbgRedirect Allows for redirecting the event pipeline DWORD UNSUPPORTED 0 REGUTIL_default
DbgRedirectApplication Specifies the auxiliary debugger application to launch. STRING EXTERNAL
DbgRedirectAttachCmd Specifies command parameters for attaching the auxiliary debugger. STRING EXTERNAL
DbgRedirectCommonCmd Specifies a command line format string for the auxiliary debugger. STRING EXTERNAL
DbgRedirectCreateCmd Specifies command parameters when creating the auxiliary debugger. STRING EXTERNAL
DbgShortcutCanary Allows a way to force canary to fail to be able to test failure paths DWORD INTERNAL 0 REGUTIL_default
DbgSkipMEOnStep Turns off MethodEnter checks DWORD INTERNAL 0 REGUTIL_default
DbgSkipStackCheck Skip the stack pointer check during stackwalking DWORD UNSUPPORTED 0 REGUTIL_default
DbgSkipVerCheck Allows different RS and LS versions (for servicing work) DWORD INTERNAL 0 REGUTIL_default
DbgTC Allows checking boundary compression for offset mappings DWORD INTERNAL 0 REGUTIL_default
DbgTransportFaultInject Allows injecting a fault for testing the debug transport DWORD INTERNAL 0 REGUTIL_default
DbgTransportLog Turns on logging for the debug transport DWORD INTERNAL
DbgTransportLogClass Mask to control what is logged in DbgTransportLog DWORD INTERNAL
DbgTransportProxyAddress Allows specifying the transport proxy address STRING UNSUPPORTED REGUTIL_default
DbgTrapOnSkip Allows breaking when we skip a breakpoint DWORD INTERNAL 0 REGUTIL_default
DbgWaitTimeout Specifies the timeout value for waits DWORD INTERNAL 1 REGUTIL_default
DbgWFDETimeout Specifies the timeout value for wait when waiting for a debug event DWORD UNSUPPORTED 25 REGUTIL_default
DebugBreakOnAssert If DACCESS_COMPILE is defined, break on asserts. DWORD INTERNAL 0 REGUTIL_default
DebugBreakOnVerificationFailure Halts the jit on verification failure DWORD INTERNAL 0 REGUTIL_default
DebuggerBreakPoint Allows counting various debug events STRING INTERNAL REGUTIL_default
Debugging_RequiredVersion The lowest ICorDebug version we should attempt to emulate, or 0 for default policy. Use 2 for CLRv2, 4 for CLRv4, etc. DWORD UNSUPPORTED 0
DebugVerify Control for tracing in peverify STRING INTERNAL REGUTIL_default
EnableDiagnostics Allows the debugger and profiler diagnostics to be disabled DWORD EXTERNAL 1 REGUTIL_default
EncApplyChanges Allows breaking when ApplyEditAndContinue is called DWORD INTERNAL 0
EnCBreakOnRemapComplete Allows breaking after N RemapCompletes DWORD INTERNAL 0 REGUTIL_default
EnCBreakOnRemapOpportunity Allows breaking after N RemapOpportunities DWORD INTERNAL 0 REGUTIL_default
EncDumpApplyChanges Allows dumping edits in delta metadata and il files DWORD INTERNAL 0
EncFixupFieldBreak Unlikely that this is used anymore. DWORD INTERNAL 0
EncJitUpdatedFunction Allows breaking when an updated function is jitted DWORD INTERNAL 0
EnCResolveField Allows breaking when computing the address of an EnC-added field DWORD INTERNAL 0
EncResumeInUpdatedFunction Allows breaking when execution resumes in a new EnC version of a function DWORD INTERNAL 0
IntentionallyCorruptDataFromTarget Intentionally fakes bad data retrieved from target to try and break dump generation. DWORD INTERNAL 0
MiniMdBufferCapacity The max size of the buffer to store mini metadata information for triage- and mini-dumps. DWORD INTERNAL 64 * 1024
RaiseExceptionOnAssert Raise a first chance (if set to 1) or second chance (if set to 2) exception on asserts. DWORD INTERNAL 0 REGUTIL_default

Diagnostics (internal general-purpose) Configuration Knobs

Name Description Type Class Default Value Flags
ConditionalContracts If ENABLE_CONTRACTS_IMPL is defined, sets whether contracts are conditional. (?) DWORD INTERNAL
ConsistencyCheck DWORD INTERNAL 0
ContinueOnAssert If set, doesn't break on asserts. DWORD INTERNAL 0 REGUTIL_default
disableStackOverflowProbing DWORD UNSUPPORTED 0 FavorConfigFile
InjectFatalError DWORD INTERNAL
InjectFault DWORD INTERNAL 0 REGUTIL_default
SuppressChecks DWORD INTERNAL
SuppressLockViolationsOnReentryFromOS 64 bit OOM tests re-enter the CLR via RtlVirtualUnwind. This indicates whether to suppress resulting locking violations. DWORD INTERNAL 0
TestHooks Used by tests to get test an insight on various CLR workings STRING INTERNAL

Exception Handling Configuration Knobs

Name Description Type Class Default Value Flags
AssertOnFailFast DWORD INTERNAL
FailFastOnCorruptedStateException Failfast if a CSE is encountered DWORD UNSUPPORTED 0 FavorConfigFile
legacyCorruptedStateExceptionsPolicy Enabled Pre-V4 CSE behavior DWORD UNSUPPORTED 0 FavorConfigFile
SuppressLostExceptionTypeAssert DWORD INTERNAL 0 REGUTIL_default

Garbage collector Configuration Knobs

Name Description Type Class Default Value Flags
BGCSpin Specifies the bgc spin time DWORD UNSUPPORTED 2
BGCSpinCount Specifies the bgc spin count DWORD UNSUPPORTED 140
FastGCCheckStack DWORD INTERNAL 0
FastGCStress Reduce the number of GCs done by enabling GCStress DWORD INTERNAL
gcAllowVeryLargeObjects Allow allocation of 2GB+ objects on GC heap DWORD EXTERNAL 1
GCBreakOnOOM Does a DebugBreak at the soonest time we detect an OOM DWORD UNSUPPORTED
GCCompactRatio Specifies the ratio compacting GCs vs sweeping DWORD UNSUPPORTED 0
gcConcurrent Enables/Disables concurrent GC DWORD UNSUPPORTED (DWORD)-1
GCConfigLogEnabled Specifies if you want to turn on config logging in GC DWORD UNSUPPORTED 0
GCConfigLogFile Specifies the name of the GC config log file STRING UNSUPPORTED
gcConservative Enables/Disables conservative GC DWORD UNSUPPORTED 0
GcCoverage Specify a method or regular expression of method names to run with GCStress STRING INTERNAL
GCCpuGroup Specifies if to enable GC to support CPU groups DWORD EXTERNAL 0
gcForceCompact When set to true, always do compacting GC DWORD UNSUPPORTED
GCgen0size Specifies the smallest gen0 size DWORD UNSUPPORTED
GCHeapCount DWORD UNSUPPORTED 0
GCLatencyLevel Specifies the GC latency level that you want to optimize for DWORD EXTERNAL 1
GCLatencyMode Specifies the GC latency mode - batch, interactive or low latency (note that the same thing can be specified via API which is the supported way) DWORD INTERNAL
GCLogEnabled Specifies if you want to turn on logging in GC DWORD UNSUPPORTED 0
GCLogFile Specifies the name of the GC log file STRING UNSUPPORTED
GCLogFileSize Specifies the GC log file size DWORD UNSUPPORTED 0
GCLOHCompact Specifies the LOH compaction mode DWORD UNSUPPORTED
GCMixLog Specifies the name of the log file for GC mix statistics STRING UNSUPPORTED
GCName STRING EXTERNAL
GCNoAffinitize DWORD UNSUPPORTED 0
GCNumaAware Specifies if to enable GC NUMA aware DWORD UNSUPPORTED 1
GCPollType DWORD EXTERNAL
GCRetainVM When set we put the segments that should be deleted on a standby list (instead of releasing them back to the OS) which will be considered to satisfy new segment requests (note that the same thing can be specified via API which is the supported way) DWORD UNSUPPORTED 0
GCSegmentSize Specifies the managed heap segment size DWORD UNSUPPORTED
gcServer Enables server GC DWORD UNSUPPORTED 0
GCStress Trigger GCs at regular intervals DWORD EXTERNAL 0 REGUTIL_default
GCStressMaxFGCsPerBGC Specifies how many FGCs will occur during one BGC in GCStressMix mode DWORD INTERNAL ~0U
GCStressMix Specifies whether the GC mix mode is enabled or not DWORD INTERNAL 0
GcStressOnDirectCalls Whether to trigger a GC on direct calls DWORD INTERNAL 0 REGUTIL_default
GCStressStart Start GCStress after N stress GCs have been attempted DWORD EXTERNAL 0
GCStressStartAtJit Start GCStress after N items are jitted DWORD INTERNAL 0
GCStressStep Specifies how often StressHeap will actually do a GC in GCStressMix mode DWORD INTERNAL 1
gcTrimCommitOnLowMemory When set we trim the committed space more aggressively for the ephemeral seg. This is used for running many instances of server processes where they want to keep as little memory committed as possible DWORD EXTERNAL
HeapVerify When set verifies the integrity of the managed heap on entry and exit of each GC DWORD UNSUPPORTED
SetupGcCoverage This doesn't appear to be a config flag STRING EXTERNAL REGUTIL_default
SkipGcCoverage Specify a list of assembly names to skip with GC Coverage STRING INTERNAL
StatsUpdatePeriod Specifies the interval, in seconds, at which to update the statistics DWORD UNSUPPORTED 60
SuspendTimeLog Specifies the name of the log file for suspension statistics STRING UNSUPPORTED

GDBJIT Configuration Knobs

Name Description Type Class Default Value Flags
GDBJitElfDump Dump ELF for specified method STRING INTERNAL
GDBJitEmitDebugFrame Enable .debug_frame generation DWORD INTERNAL TRUE

IBC Configuration Knobs

Name Description Type Class Default Value Flags
ConvertIbcData Converts between v1 and v2 IBC data DWORD UNSUPPORTED 1 REGUTIL_default
DisableHotCold Master hot/cold splitting switch in Jit64 DWORD UNSUPPORTED
DisableIBC Disables the use of IBC data DWORD UNSUPPORTED 0 REGUTIL_default
UseIBCFile DWORD EXTERNAL 0 REGUTIL_default

Interop Configuration Knobs

Name Description Type Class Default Value Flags
AllowDComReflection Allows out of process DCOM clients to marshal blocked reflection types. DWORD EXTERNAL 0
EnableEventPipe Enable/disable event pipe. Non-zero values enable tracing. DWORD INTERNAL 0
EnableRCWCleanupOnSTAShutdown Performs RCW cleanup when STA shutdown is detected using IInitializeSpy in classic processes. DWORD INTERNAL 0
EventPipeConfig Configuration for EventPipe. STRING INTERNAL
EventPipeOutputFile The full path including file name for the trace file that will be written when COMPlus_EnableEventPipe&=1 STRING INTERNAL
EventPipeRundown Enable/disable eventpipe rundown. DWORD INTERNAL 1
ExposeExceptionsInCOM DWORD INTERNAL
InteropLogArguments Log all pinned arguments passed to an interop call DWORD EXTERNAL 0
InteropValidatePinnedObjects After returning from a managed-to-unmanaged interop call, validate GC heap around objects pinned by IL stubs. DWORD UNSUPPORTED 0
legacyComHierarchyVisibility DWORD EXTERNAL
legacyComVTableLayout DWORD EXTERNAL
LocalWinMDPath Additional path to probe for WinMD files in if a WinRT type is not resolved using the standard paths. STRING INTERNAL
LogCCWRefCountChange Outputs debug information and calls LogCCWRefCountChange_BREAKPOINT when AddRef or Release is called on a CCW. STRING UNSUPPORTED
newComVTableLayout DWORD EXTERNAL
PInvokeInline STRING EXTERNAL REGUTIL_default
PreferComInsteadOfManagedRemoting When communicating with a cross app domain CCW, use COM instead of managed remoting. DWORD EXTERNAL 0

Interpreter Configuration Knobs

Name Description Type Class Default Value Flags
DumpInterpreterStubs Prints all interpreter stubs that are created to the console DWORD INTERNAL 0
Interpret Selectively uses the interpreter to execute the specified methods STRING INTERNAL REGUTIL_default
InterpreterDoLoopMethods If set, don't check for loops, start by interpreting all methods DWORD INTERNAL 0
InterpreterFallback Fallback to the interpreter when the JIT compiler fails DWORD INTERNAL 0
InterpreterJITThreshold The number of times a method should be interpreted before being JITted DWORD INTERNAL 10
InterpreterLogFile If non-null, append interpreter logging to this file, else use stdout STRING INTERNAL REGUTIL_default
InterpreterLooseRules If non-zero, allow ECMA spec violations required by managed C++. DWORD INTERNAL 1 REGUTIL_default
InterpreterMethHashMax If non-zero, only interpret methods selected by 'Interpret' whose hash is at most this value DWORD INTERNAL UINT32_MAX
InterpreterMethHashMin Only interpret methods selected by 'Interpret' whose hash is at least this value. or after nth DWORD INTERNAL 0
InterpreterPrintPostMortem Prints summary information about the execution to the console DWORD INTERNAL 0
InterpreterStubMax If non-zero, only interpret methods selected by 'Interpret' whose stub number is at most this value. DWORD INTERNAL UINT32_MAX
InterpreterStubMin Only interpret methods selected by 'Interpret' whose stub num is at least this value. DWORD INTERNAL 0
InterpreterUseCaching If non-zero, use the caching mechanism. DWORD INTERNAL 1 REGUTIL_default
InterpretExclude Excludes the specified methods from the set selected by 'Interpret' STRING INTERNAL REGUTIL_default
TraceInterpreterEntries Logs entries to interpreted methods to the console DWORD INTERNAL 0
TraceInterpreterIL Logs individual instructions of interpreted methods to the console DWORD INTERNAL 0
TraceInterpreterJITTransition Logs when the interpreter determines a method should be JITted DWORD INTERNAL 0
TraceInterpreterOstack Logs operand stack after each IL instruction of interpreted methods to the console DWORD INTERNAL 0
TraceInterpreterVerbose Logs interpreter progress with detailed messages to the console DWORD INTERNAL 0

JIT Configuration Knobs

Name Description Type Class Default Value Flags
`` STRING JitMeasureNowayAssertFile
AltJit Enables AltJit and selectively limits it to the specified methods. STRING EXTERNAL REGUTIL_default
AltJitAssertOnNYI Controls the AltJit behavior of NYI stuff DWORD INTERNAL 0
AltJitExcludeAssemblies Do not use AltJit on this semicolon-delimited list of assemblies. STRING EXTERNAL REGUTIL_default
AltJitLimit Max number of functions to use altjit for (decimal) DWORD 0
AltJitName Alternative Jit to use, will fall back to primary jit. STRING EXTERNAL REGUTIL_default
AltJitNgen Enables AltJit for NGEN and selectively limits it to the specified methods. STRING INTERNAL REGUTIL_default
AltJitSkipOnAssert If AltJit hits an assert, fall back to the fallback JIT. Useful in conjunction with COMPlus_ContinueOnAssert=1 DWORD 0
BreakOnDumpToken Breaks when using internal logging on a particular token value. DWORD 0xffffffff
DebugBreakOnVerificationFailure Halts the jit on verification failure DWORD 0
DumpJittedMethods Prints all jitted methods to the console DWORD 0
EnableAVX Enable AVX instruction set for wide operations as default DWORD EXTERNAL EXTERNAL_JitEnableAVX_Default REGUTIL_default
FeatureSIMD Enable SIMD intrinsics recognition in System.Numerics.dll and/or System.Numerics.Vectors.dll DWORD EXTERNAL EXTERNAL_FeatureSIMD_Default REGUTIL_default
InjectFault DWORD Should 0
InterpreterFallback Fallback to the interpreter when the JIT compiler fails DWORD 0
JitAggressiveInlining Aggressive inlining of all methods DWORD 0
JitAlignLoops Aligns loop targets to 8 byte boundaries DWORD UNSUPPORTED
JitAssertOnMaxRAPasses DWORD 0
JitBreak Stops in the importer when compiling a specified method SSV
JitBreakEmit DWORD INTERNAL (DWORD)-1 REGUTIL_default
JitBreakEmitOutputInstr DWORD -1
JitBreakMorphTree DWORD 0xffffffff
JitBreakOnBadCode DWORD 0
JITBreakOnMinOpts Halt if jit switches to MinOpts DWORD JitBreakOnMinOpts 0
JitBreakOnUnsafeCode DWORD 0
JitCanUseSSE2 DWORD -1
JitCloneLoops If 0, don't clone. Otherwise clone loops for optimizations. DWORD 1
JitComponentUnitTests Run JIT component unit tests DWORD RunComponentUnitTests 0
JitDebugBreak SSV
JitDebuggable DWORD INTERNAL
JitDebugLogLoopCloning In debug builds log places where loop cloning optimizations are performed on the fast path. DWORD 0
JitDefaultFill In debug builds, initialize the memory allocated by the nra with this byte. DWORD 0xdd
JitDiffableDasm Make the disassembly diff-able DWORD DiffableDasm 0
JitDirectAlloc DWORD 0
JitDisasm Dumps disassembly for specified method SSV
JitDoAssertionProp Perform assertion propagation optimization DWORD 1
JitDoCopyProp Perform copy propagation on variables that appear redundant DWORD 1
JitDoEarlyProp Perform Early Value Propagation DWORD 1
JitDoLoopHoisting Perform loop hoisting on loop invariant values DWORD 1
JitDoRangeAnalysis Perform range check analysis DWORD 1
JitDoSsa Perform Static Single Assignment (SSA) numbering on the variables DWORD 1
JitDoubleAlign DWORD 1
JitDoValueNumber Perform value numbering on method expressions DWORD 1
JitDump Dumps trees for specified method SSV
JitDumpASCII Uses only ASCII characters in tree dumps DWORD 1
JitDumpBeforeAfterMorph If 1, display each tree before/after morphing DWORD TreesBeforeAfterMorph 0
JitDumpFg Dumps Xml/Dot Flowgraph for specified method STRING
JitDumpFgDir Directory for Xml/Dot flowgraph dump(s) STRING
JitDumpFgDot Set to non-zero to emit Dot instead of Xml Flowgraph dump DWORD 0
JitDumpFgFile Filename for Xml/Dot flowgraph dump(s) STRING
JitDumpFgPhase Phase-based Xml/Dot flowgraph support. Set to the short name of a phase to see the flowgraph after that phase. Leave unset to dump after COLD-BLK (determine first cold block) or set to * for all phases STRING
JitDumpIR Dumps trees (in linear IR form) for specified method SSV
JitDumpIRFormat Comma separated format control for JitDumpIR, values = {types | locals | ssa | valnums | kinds | flags | nodes | nolists | nostmts | noleafs | trees | dataflow} STRING
JitDumpIRPhase Phase control for JitDumpIR, values = {* | phasename} STRING
JitDumpTerseLsra Produce terse dump output for LSRA DWORD 1
JitDumpToDebugger Output JitDump output to the debugger DWORD 0
JitDumpVerboseSsa Produce especially verbose dump output for SSA DWORD 0
JitDumpVerboseTrees Enable more verbose tree dumps DWORD 0
JitEECallTimingInfo DWORD 0
JitEHDump Dump the EH table for the method, as reported to the VM SSV
JitELTHookEnabled On ARM, setting this will emit Enter/Leave/TailCall callbacks DWORD INTERNAL 0
JitEmitPrintRefRegs DWORD 0
JitEnableDevirtualization Enable devirtualization in importer DWORD 1
JitEnableFinallyCloning DWORD 1
JitEnableLateDevirtualization Enable devirtualization after inlining DWORD 1
JitEnableNoWayAssert DWORD INTERNAL INTERNAL_JitEnableNoWayAssert_Default REGUTIL_default
JitEnablePCRelAddr Whether absolute addr be encoded as PC-rel offset by RyuJIT where possible DWORD EnablePCRelAddr 1
JitEnableRemoveEmptyTry DWORD 1
JitExclude SSV
JitExpensiveDebugCheckLevel Level indicates how much checking beyond the default to do in debug builds (currently 1-2) DWORD 0
JitForceFallback Set to non-zero to test NOWAY assert by forcing a retry DWORD 0
JitForceProcedureSplitting SSV
JitForceVer DWORD 0
JitFramed Forces EBP frames DWORD UNSUPPORTED
JitFullyInt Forces Fully interruptible code DWORD 0
JitFuncInfoLogFile If set, gather JIT function info and write to this file. STRING INTERNAL
JitFunctionTrace If non-zero, print JIT start/end logging DWORD 0
JitGCChecks DWORD 0
JitGCDump SSV
JitGCInfoLogging If true, prints GCInfo-related output to standard output. DWORD 0
JitGCStress GC stress mode for jit DWORD INTERNAL 0 REGUTIL_default
JitHalt Emits break instruction into jitted code SSV
JitHashBreak Same as JitBreak, but for a method hash DWORD -1
JitHashDump Same as JitDump, but for a method hash DWORD -1
JitHashDumpIR Same as JitDumpIR, but for a method hash DWORD -1
JitHashHalt Same as JitHalt, but for a method hash DWORD -1
JitHeartbeat DWORD INTERNAL 0
JitHelperLogging DWORD INTERNAL 0
JitImportBreak SSV
JitInclude SSV
JitInlineAdditionalMultiplier DWORD 0
JITInlineDepth DWORD JitInlineDepth DEFAULT_MAX_INLINE_DEPTH
JitInlineDumpData DWORD 0
JitInlineDumpXml 1 = full xml (+ failures in DEBUG) 2 = only methods with inlines (+ failures in DEBUG) 3 = only methods with inlines, no failures DWORD 0
JitInlineLimit DWORD -1
JitInlinePolicyDiscretionary DWORD 0
JitInlinePolicyFull DWORD 0
JitInlinePolicyModel DWORD 0
JitInlinePolicyRandom nonzero enables; value is the external random seed DWORD 0
JitInlinePolicyReplay DWORD 0
JitInlinePolicySize DWORD 0
JitInlinePrintStats DWORD 0
JitInlineReplayFile STRING
JitInlineSIMDMultiplier DWORD 3
JITInlineSize DWORD JitInlineSize DEFAULT_MAX_INLINE_SIZE
JitLargeBranches Force using the largest conditional branch format DWORD INTERNAL 0 REGUTIL_default
JitLateDisasm SSV
JITLateDisasmTo STRING JitLateDisasmTo
JitLockWrite Force all volatile writes to be 'locked' DWORD INTERNAL 0
JitLongAddress Force using the large pseudo instruction form for long address DWORD 0
JitLoopHoistStats Display JIT loop hoisting statistics DWORD DisplayLoopHoistStats 0
JitLsraStats Display JIT Linear Scan Register Allocator statistics DWORD DisplayLsraStats 0
JITMaxTempAssert DWORD JitMaxTempAssert 1
JitMaxUncheckedOffset DWORD 8
JitMeasureIR If set, measure the IR size after some phases and report it in the time log. DWORD 0
JitMeasureNowayAssert Set to 1 to measure noway_assert usage. Only valid if MEASURE_NOWAY is defined. DWORD 0
JitMemStats Display JIT memory usage statistics DWORD INTERNAL 0 REGUTIL_default
JITMinOpts Forces MinOpts DWORD UNSUPPORTED
JITMinOptsBbCount Internal jit control of MinOpts DWORD JitMinOptsBbCount DEFAULT_MIN_OPTS_BB_COUNT
JITMinOptsCodeSize Internal jit control of MinOpts DWORD JitMinOptsCodeSize DEFAULT_MIN_OPTS_CODE_SIZE
JITMinOptsInstrCount Internal jit control of MinOpts DWORD JitMinOptsInstrCount DEFAULT_MIN_OPTS_INSTR_COUNT
JITMinOptsLvNumcount Internal jit control of MinOpts DWORD JitMinOptsLvNumCount DEFAULT_MIN_OPTS_LV_NUM_COUNT
JITMinOptsLvRefcount Internal jit control of MinOpts DWORD JitMinOptsLvRefCount DEFAULT_MIN_OPTS_LV_REF_COUNT
JITMinOptsName Forces MinOpts for a named function SSV JitMinOptsName
JitMinOptsTrackGCrefs Track GC roots DWORD JitMinOptsTrackGCrefs_Default
JitName Primary Jit to use STRING EXTERNAL
JitNoCMOV DWORD 0
JitNoCSE DWORD 0
JitNoCSE2 DWORD 0
JitNoForceFallback Set to non-zero to prevent NOWAY assert testing. Overrides COMPlus_JitForceFallback and JIT stress flags. DWORD 0
JitNoHoist DWORD 0
JitNoInline Disables inlining of all methods DWORD 0
JitNoInlineRange STRING
JitNoMemoryBarriers If 1, don't generate memory barriers DWORD 0
JitNoProcedureSplitting Disallow procedure splitting for specified methods SSV
JitNoProcedureSplittingEH Disallow procedure splitting for specified methods if they contain exception handling SSV
JitNoRegLoc DWORD 0
JitNoRngChks If 1, don't generate range checks DWORD JitNoRangeChks 0
JitNoStructPromotion Disables struct promotion in Jit32 DWORD 0
JitNoUnroll DWORD 0
JitOptimizeType DWORD EXTERNAL
JitOptRepeat Runs optimizer multiple times on the method SSV
JitOptRepeatCount Number of times to repeat opts when repeating DWORD 2
JitOrder DWORD 0
JITPInvokeCheckEnabled DWORD JitPInvokeCheckEnabled 0
JITPInvokeEnabled DWORD JitPInvokeEnabled 1
JitPrintDevirtualizedMethods DWORD 0
JitPrintInlinedMethods DWORD EXTERNAL 0 REGUTIL_default
JitRange STRING
JitRegisterFP Control FP enregistration DWORD EXTERNAL 3 REGUTIL_default
JitReportFastTailCallDecisions DWORD 0
JITRequired DWORD JitRequired -1
JITRoundFloat DWORD JitRoundFloat DEFAULT_ROUND_LEVEL
JitSkipArrayBoundCheck DWORD 0
JitSlowDebugChecksEnabled Turn on slow debug checks DWORD 1
JitSplitFunctionSize On ARM, use this as the maximum function/funclet size for creating function fragments (and creating multiple RUNTIME_FUNCTION entries) DWORD 0
JitSsaStress Perturb order of processing of blocks in SSA; 0 = no stress; 1 = use method hash; * = supplied value as random hash DWORD 0
JitStackAllocToLocalSize DWORD DEFAULT_MAX_LOCALLOC_TO_LOCAL_SIZE
JitStackChecks DWORD 0
JitStackProbes DWORD StackProbesOverride 0
JitStress Internal Jit stress mode: 0 = no stress, 2 = all stress, other = vary stress based on a hash of the method and this value DWORD 0
JitStressBBProf Internal Jit stress mode DWORD 0
JitStressBiasedCSE Internal Jit stress mode: decimal bias value between (0,100) to perform CSE on a candidate. 100% = All CSEs. 0% = 0 CSE. (> 100) means no stress. DWORD 0x101
JitStressFP Internal Jit stress mode DWORD 0
JitStressModeNames Internal Jit stress mode: stress using the given set of stress mode names, e.g. STRESS_REGS, STRESS_TAILCALL STRING
JitStressModeNamesNot Internal Jit stress mode: do NOT stress using the given set of stress mode names, e.g. STRESS_REGS, STRESS_TAILCALL STRING
JitStressModeNamesOnly Internal Jit stress: if nonzero, only enable stress modes listed in JitStressModeNames DWORD 0
JitStressOnly Internal Jit stress mode: stress only the specified method(s) SSV
JitStressRange Internal Jit stress mode STRING
JitStressRegs DWORD 0
JitStrictCheckForNonVirtualCallToVirtualMethod DWORD 1
JitTelemetry If non-zero, gather JIT telemetry data DWORD EXTERNAL 1
JitTimeLogCsv If set, gather JIT throughput data and write to a CSV file. This mode must be used in internal retail builds. STRING INTERNAL
JitTimeLogFile If set, gather JIT throughput data and write to this file. STRING INTERNAL
JitUnwindDump Dump the unwind codes for the method SSV
JitVerificationDisable DWORD INTERNAL
JitVNMapSelBudget Max # of MapSelect's considered for a particular top-level invocation. DWORD INTERNAL 100
JitVNMapSelLimit If non-zero, assert if # of VNF_MapSelect applications considered reaches this DWORD 0
MultiCoreJitProfile If set, use the file to store/control multi-core JIT. STRING INTERNAL
MultiCoreJitProfileWriteDelay Set the delay after which the multi-core JIT profile will be written to disk. DWORD INTERNAL 12
NetFx40_PInvokeStackResilience Makes P/Invoke resilient against mismatched signature and calling convention (significant perf penalty). DWORD EXTERNAL (DWORD)-1
NgenHashDump same as JitHashDump, but for ngen DWORD -1
NgenHashDumpIR same as JitHashDumpIR, but for ngen DWORD -1
NgenOrder DWORD 0
RunAltJitCode If non-zero, and the compilation succeeds for an AltJit, then use the code. If zero, then we always throw away the generated code and fall back to the default compiler. DWORD 1
SIMD16ByteOnly Limit maximum SIMD vector length to 16 bytes (used by x64_arm64_altjit) DWORD INTERNAL 0
StackSamplingAfter When to start sampling (for some sort of app steady state), i.e., initial delay for sampling start in milliseconds. DWORD UNSUPPORTED 0
StackSamplingEnabled Is stack sampling based tracking of evolving hot methods enabled. DWORD UNSUPPORTED 0
StackSamplingEvery How frequent should thread stacks be sampled in milliseconds. DWORD UNSUPPORTED 100
StackSamplingNumMethods Number of evolving methods to track as hot and JIT them in the background at a given point of execution. DWORD UNSUPPORTED 32
StressCOMCall DWORD 0
TailCallLoopOpt Convert recursive tail calls to loops DWORD EXTERNAL 1
TailCallMax STRING INTERNAL REGUTIL_default
TailCallOpt STRING EXTERNAL REGUTIL_default
TailcallStress DWORD 0

JIT Hardware Intrinsics Configuration Knobs

Name Description Type Class Default Value Flags
EnableAES Enable AES DWORD 1
EnableAVX DWORD 1
EnableAVX2 Enable AVX2 DWORD 1
EnableBMI1 Enable BMI1 DWORD 1
EnableBMI2 Enable BMI2 DWORD 1
EnableFMA Enable FMA DWORD 1
EnableIncompleteISAClass Enable testing not-yet-implemented intrinsic classes DWORD 0
EnableLZCNT Enable AES DWORD 1
EnablePCLMULQDQ Enable PCLMULQDQ DWORD 1
EnablePOPCNT Enable POPCNT DWORD 1
EnableSSE Enable SSE DWORD 1
EnableSSE2 Enable SSE2 DWORD 1
EnableSSE3 Enable SSE3 DWORD 1
EnableSSE3_4 Enable SSE3, SSSE3, SSE 4.1 and 4.2 instruction set as default DWORD 1
EnableSSE41 Enable SSE41 DWORD 1
EnableSSE42 Enable SSE42 EnableAVX is already defined for DEBUG and non-DEBUG mode both DWORD 1
EnableSSSE3 Enable SSSE3 DWORD 1

Jit Pitching Configuration Knobs

Name Description Type Class Default Value Flags
JitPitchEnabled Set it to 1 to enable Jit Pitching DWORD INTERNAL (DWORD)0
JitPitchMaxVal Do Jit Pitching the value of the inner counter less then this value (for debuggin purpose only) DWORD INTERNAL (DWORD)0xffffffff
JitPitchMemThreshold Do Jit Pitching when code heap usage is larger than this (in bytes) DWORD INTERNAL (DWORD)0
JitPitchMethodSizeThreshold Do Jit Pitching for methods whose native code size larger than this (in bytes) DWORD INTERNAL (DWORD)0
JitPitchMinVal Do Jit Pitching if the value of the inner counter greater than this value (for debugging purpose only) DWORD INTERNAL (DWORD)0
JitPitchPrintStat Print statistics about Jit Pitching DWORD INTERNAL (DWORD)0
JitPitchTimeInterval Time interval between Jit Pitchings in ms DWORD INTERNAL (DWORD)0

Loader Configuration Knobs

Name Description Type Class Default Value Flags
APIThreadStress Used to test Loader for race conditions DWORD INTERNAL
CoreClrBinderLog Debug flag that enabled detailed log for new binder (similar to stress logging). STRING INTERNAL
DisableFXClosureWalk Disable full closure walks even in the presence of FX binding redirects DWORD INTERNAL 0
DisableIJWVersionCheck Don't perform the new version check that prevents unsupported IJW in-proc SxS. DWORD EXTERNAL 0
EnableFastBindClosure If set to >0 the binder uses CFastAssemblyBindingClosure instances DWORD UNSUPPORTED 0
ForceLog Fusion flag to enforce assembly binding log. Heavily used and documented in MSDN and BLOGS. DWORD EXTERNAL
LoaderOptimization Controls code sharing behavior DWORD EXTERNAL
TagAssemblyNames Enable CAssemblyName::_tag field for more convenient debugging. DWORD INTERNAL 0
WinMDPath Path for Windows WinMD files STRING INTERNAL

Loader heap Configuration Knobs

Name Description Type Class Default Value Flags
BreakOnOutOfMemoryWithinRange Break before out of memory within range exception is thrown DWORD INTERNAL 0
CodeHeapReserveForJumpStubs Percentage of code heap to reserve for jump stubs DWORD INTERNAL 1
LoaderHeapCallTracing Loader heap troubleshooting DWORD INTERNAL 0 REGUTIL_default
NGenReserveForJumpStubs Percentage of ngen image size to reserve for jump stubs DWORD INTERNAL 0

Log Configuration Knobs

Name Description Type Class Default Value Flags
LogEnable Turns on the traditional CLR log. DWORD INTERNAL
LogFacility Specifies a facility mask for CLR log. (See 'loglf.h'; VM interprets string value as hex number.) Also used by stresslog. DWORD INTERNAL
LogFacility2 Specifies a facility mask for CLR log. (See 'loglf.h'; VM interprets string value as hex number.) Also used by stresslog. DWORD INTERNAL
logFatalError Specifies whether EventReporter logs fatal errors in the Windows event log. DWORD EXTERNAL 1
LogFile Specifies a file name for the CLR log. STRING INTERNAL REGUTIL_default
LogFileAppend Specifies whether to append to or replace the CLR log file. DWORD INTERNAL
LogFlushFile Specifies whether to flush the CLR log file on each write. DWORD INTERNAL
LogLevel 4=10 msgs, 9=1000000, 10=everything DWORD EXTERNAL
LogPath ?Fusion debug log path. STRING INTERNAL
LogToConsole Writes the CLR log to console. DWORD INTERNAL
LogToDebugger Writes the CLR log to debugger (OutputDebugStringA). DWORD INTERNAL
LogToFile Writes the CLR log to a file. DWORD INTERNAL
LogWithPid Appends pid to filename for the CLR log. DWORD INTERNAL

MetaData Configuration Knobs

Name Description Type Class Default Value Flags
AssertOnBadImageFormat ASSERT when invalid MD read DWORD INTERNAL
MD_ApplyDeltaBreak ASSERT when applying EnC DWORD INTERNAL 0 REGUTIL_default
MD_DeltaCheck Some checks of GUID when applying EnC (?) DWORD INTERNAL 1 REGUTIL_default
MD_EncDelta Forces EnC Delta format in MD (?) DWORD INTERNAL 0 REGUTIL_default
MD_ForceNoColDesSharing Don't know - the only usage I could find is #if 0 (?) DWORD INTERNAL 0 REGUTIL_default
MD_KeepKnownCA Something with known CAs (?) DWORD INTERNAL 0 REGUTIL_default
MD_MiniMDBreak ASSERT when creating CMiniMdRw class DWORD INTERNAL 0 REGUTIL_default
MD_PreSaveBreak ASSERT when calling CMiniMdRw::PreSave DWORD INTERNAL 0 REGUTIL_default
MD_PreserveDebuggerMetadataMemory Save all versions of metadata memory in the debugger when debuggee metadata is updated DWORD EXTERNAL 0 REGUTIL_default
MD_RegMetaBreak ASSERT when creating RegMeta class DWORD INTERNAL 0 REGUTIL_default
MD_RegMetaDump Dump MD in 4 functions (?) DWORD INTERNAL 0 REGUTIL_default
MD_WinMD_AssertOnIllegalUsage ASSERT if a WinMD import adapter detects a tool incompatibility DWORD INTERNAL 0 REGUTIL_default
MD_WinMD_Disable Never activate the WinMD import adapter DWORD INTERNAL 0 REGUTIL_default

Native Binder Configuration Knobs

Name Description Type Class Default Value Flags
NgenBind_ZapForbid Assert if an assembly succeeds in binding to a native image DWORD INTERNAL 0
NgenBind_ZapForbidExcludeList STRING INTERNAL
NgenBind_ZapForbidList STRING INTERNAL
SymDiffDump Used to create the map file while binding the assembly. Used by SemanticDiffer DWORD INTERNAL 0 REGUTIL_default

NGEN Configuration Knobs

Name Description Type Class Default Value Flags
CrossGenAssumeInputSigned CrossGen should assume that its input assemblies will be signed before deployment DWORD INTERNAL 1
EnableHardbinding Enables the use of hardbinding DWORD INTERNAL 0 REGUTIL_default
HardPrejitEnabled DWORD EXTERNAL
NGen_JitName STRING EXTERNAL REGUTIL_default
NgenAllowMscorlibSoftbind Disable forced hard-binding to mscorlib DWORD INTERNAL 0
NgenDisasm Same as JitDisasm, but for ngen SSV
NgenDump Same as JitDump, but for ngen SSV
NgenDumpFg Ngen Xml Flowgraph support STRING
NgenDumpFgDir Ngen Xml Flowgraph support STRING
NgenDumpFgFile Ngen Xml Flowgraph support STRING
NgenDumpIR Same as JitDumpIR, but for ngen SSV
NgenDumpIRFormat Same as JitDumpIRFormat, but for ngen STRING
NgenDumpIRPhase Same as JitDumpIRPhase, but for ngen STRING
NgenEHDump Dump the EH table for the method, as reported to the VM SSV
NGenEnableCreatePdb If set to >0 ngen.exe displays help on, recognizes createpdb in the command line DWORD UNSUPPORTED 0
NgenForceFailureCount If set to >0 and we have IBC data we will force a failure after we reference an IBC data item times DWORD INTERNAL 0 REGUTIL_default
NgenForceFailureKind If set to 1, We will throw a TypeLoad exception; If set to 2, We will cause an A/V DWORD INTERNAL 1 REGUTIL_default
NgenForceFailureMask Bitmask used to control which locations will check and raise the failure (defaults to bits: -1) DWORD INTERNAL -1 REGUTIL_default
NGenFramed Same as JitFramed, but for ngen DWORD UNSUPPORTED -1 REGUTIL_default
NgenGCDump SSV
NGenOnlyOneMethod DWORD INTERNAL 0 REGUTIL_default
NgenOrder DWORD INTERNAL 0 REGUTIL_default
NGenSimulateDiskFull If set to 1, ngen will throw a Disk full exception in ZapWriter.cpp:Save() DWORD INTERNAL 0
NgenUnwindDump Dump the unwind codes for the method SSV
NoASLRForNgen Turn off IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE bit in generated ngen images. Makes nidump output repeatable from run to run. DWORD INTERNAL 0
PartialNGen Generate partial NGen images DWORD INTERNAL -1
partialNGenStress DWORD INTERNAL 0 REGUTIL_default
ZapDoNothing DWORD INTERNAL 0 REGUTIL_default

Performance Configuration Knobs

Name Description Type Class Default Value Flags
performanceScenario Activates a set of workload-specific default values for performance settings STRING EXTERNAL

Profiling API / ETW Configuration Knobs

Name Description Type Class Default Value Flags
AttachThreadAlwaysOn Forces profapi attach thread to be created on startup, instead of on-demand. DWORD EXTERNAL
COR_ENABLE_PROFILING Flag to indicate whether profiling should be enabled for the currently running process. DWORD EXTERNAL 0 DontPrependCOMPlus_ | IgnoreConfigFiles
COR_PROFILER Specifies GUID of profiler to load into currently running process STRING EXTERNAL DontPrependCOMPlus_
COR_PROFILER_PATH Specifies the path to the DLL of profiler to load into currently running process STRING EXTERNAL DontPrependCOMPlus_
COR_PROFILER_PATH_32 Specifies the path to the DLL of profiler to load into currently running 32 bits process STRING EXTERNAL DontPrependCOMPlus_
COR_PROFILER_PATH_64 Specifies the path to the DLL of profiler to load into currently running 64 bits process STRING EXTERNAL DontPrependCOMPlus_
CORECLR_ENABLE_PROFILING CoreCLR only: Flag to indicate whether profiling should be enabled for the currently running process. DWORD EXTERNAL 0 DontPrependCOMPlus_ | IgnoreConfigFiles
CORECLR_PROFILER CoreCLR only: Specifies GUID of profiler to load into currently running process STRING EXTERNAL DontPrependCOMPlus_
CORECLR_PROFILER_PATH CoreCLR only: Specifies the path to the DLL of profiler to load into currently running process STRING EXTERNAL DontPrependCOMPlus_
CORECLR_PROFILER_PATH_32 CoreCLR only: Specifies the path to the DLL of profiler to load into currently running 32 process STRING EXTERNAL DontPrependCOMPlus_
CORECLR_PROFILER_PATH_64 CoreCLR only: Specifies the path to the DLL of profiler to load into currently running 64 process STRING EXTERNAL DontPrependCOMPlus_
ETW_ObjectAllocationEventsPerTypePerSec Desired number of GCSampledObjectAllocation ETW events to be logged per type per second. If 0, then the default built in to the implementation for the enabled event (e.g., High, Low), will be used. STRING UNSUPPORTED REGUTIL_default
ETWEnabled This flag is used on OSes < Vista to enable/disable ETW. It is disabled by default DWORD EXTERNAL 0 REGUTIL_default
MsBetweenAttachCheck DWORD EXTERNAL 500
PerfMapEnabled This flag is used on Linux to enable writing /tmp/perf-$pid.map. It is disabled by default DWORD EXTERNAL 0 REGUTIL_default
PerfMapIgnoreSignal When perf map is enabled, this option will configure the specified signal to be accepted and ignored as a marker in the perf logs. It is disabled by default DWORD EXTERNAL 0 REGUTIL_default
ProfAPI_AttachProfilerMinTimeoutInMs Timeout in ms for the minimum time out value of AttachProfiler DWORD EXTERNAL 10*1000
ProfAPI_DetachMaxSleepMs The maximum time, in milliseconds, the CLR will wait before checking whether a profiler that is in the process of detaching is ready to be unloaded. DWORD EXTERNAL 0
ProfAPI_DetachMinSleepMs The minimum time, in milliseconds, the CLR will wait before checking whether a profiler that is in the process of detaching is ready to be unloaded. DWORD EXTERNAL 0
ProfAPI_EnableRejitDiagnostics Enable extra dumping to stdout of rejit structures DWORD INTERNAL 0
ProfAPI_ProfilerCompatibilitySetting Specifies the profiler loading policy (the default is not to load a V2 profiler in V4) STRING EXTERNAL REGUTIL_default | TrimWhiteSpaceFromStringValue
ProfAPI_TestOnlyEnableICorProfilerInfo Test-only flag to allow attaching profiler tests to call ICorProfilerInfo interface, which would otherwise be disallowed for attaching profilers DWORD INTERNAL 0
ProfAPI_ValidateNGENInstrumentation This flag enables additional validations when using the IMetaDataEmit APIs for NGEN'ed images to ensure only supported edits are made. DWORD UNSUPPORTED 0
ProfAPIFault Test-only bitmask to inject various types of faults in the profapi code DWORD INTERNAL 0
ProfAPIMaxWaitForTriggerMs Timeout in ms for profilee to wait for each blocking operation performed by trigger app. DWORD EXTERNAL 5*60*1000
StartupDelayMS STRING EXTERNAL
TestOnlyAllowedEventMask Test-only bitmask to allow profiler tests to override CLR enforcement of COR_PRF_ALLOWABLE_AFTER_ATTACH and COR_PRF_MONITOR_IMMUTABLE DWORD INTERNAL 0
TestOnlyEnableObjectAllocatedHook Test-only flag that forces CLR to initialize on startup as if ObjectAllocated callback were requested, to enable post-attach ObjectAllocated functionality. DWORD INTERNAL 0
TestOnlyEnableSlowELTHooks Test-only flag that forces CLR to initialize on startup as if slow-ELT were requested, to enable post-attach ELT functionality. DWORD INTERNAL 0

Spinning heuristics Configuration Knobs

Name Description Type Class Default Value Flags
Monitor_SpinCount Hex value specifying the maximum number of spin iterations Monitor may perform upon contention on acquiring the lock before waiting. DWORD INTERNAL 0x1e EEConfig_default
SpinBackoffFactor Hex value specifying the growth of each successive spin duration DWORD EXTERNAL 0x3 EEConfig_default
SpinInitialDuration Hex value specifying the first spin duration DWORD EXTERNAL 0x32 EEConfig_default
SpinLimitConstant Hex value specifying the constant to add when calculating the maximum spin duration DWORD EXTERNAL 0x0 EEConfig_default
SpinLimitProcCap Hex value specifying the largest value of NumProcs to use when calculating the maximum spin duration DWORD EXTERNAL 0xFFFFFFFF EEConfig_default
SpinLimitProcFactor Hex value specifying the multiplier on NumProcs to use when calculating the maximum spin duration DWORD EXTERNAL 0x4E20 EEConfig_default
SpinRetryCount Hex value specifying the number of times the entire spin process is repeated (when applicable) DWORD EXTERNAL 0xA EEConfig_default

Stress Configuration Knobs

Name Description Type Class Default Value Flags
ForceEnc Forces Edit and Continue to be on for all eligible modules. DWORD UNSUPPORTED
StressCOMCall DWORD INTERNAL 0 REGUTIL_default
StressLog Turns on the stress log. DWORD UNSUPPORTED
StressLogSize Stress log size in bytes per thread. DWORD UNSUPPORTED
StressOn Enables the STRESS_ASSERT macro that stops runtime quickly (to prevent the clr state from changing significantly before breaking) DWORD INTERNAL
stressSynchronized Unknown if or where this is used; unless a test is specifically depending on this, it can be removed. DWORD INTERNAL 0 REGUTIL_default
StressThreadCount DWORD EXTERNAL

Thread (miscellaneous) Configuration Knobs

Name Description Type Class Default Value Flags
Thread_DeadThreadCountThresholdForGCTrigger In the heuristics to clean up dead threads, this threshold must be reached before triggering a GC will be considered. Set to 0 to disable triggering a GC based on dead threads. DWORD INTERNAL 75
Thread_DeadThreadGCTriggerPeriodMilliseconds In the heuristics to clean up dead threads, this much time must have elapsed since the previous max-generation GC before triggering another GC will be considered DWORD INTERNAL 1000 * 60 * 30

Thread Suspend Configuration Knobs

Name Description Type Class Default Value Flags
DiagnosticSuspend DWORD INTERNAL 0
SuspendDeadlockTimeout DWORD INTERNAL 40000
SuspendThreadDeadlockTimeoutMs DWORD INTERNAL 2000
ThreadSuspendInjection Specifies whether to inject activations for thread suspension on Unix DWORD INTERNAL 1

Threadpool Configuration Knobs

Name Description Type Class Default Value Flags
HillClimbing_Bias The 'cost' of a thread. 0 means drive for increased throughput regardless of thread count; higher values bias more against higher thread counts. DWORD INTERNAL 15
HillClimbing_Disable Disables hill climbing for thread adjustments in the thread pool DWORD INTERNAL 0
HillClimbing_ErrorSmoothingFactor DWORD INTERNAL 1
HillClimbing_GainExponent The exponent to apply to the gain, times 100. 100 means to use linear gain, higher values will enhance large moves and damp small ones. DWORD INTERNAL 200
HillClimbing_MaxChangePerSample DWORD INTERNAL 20
HillClimbing_MaxChangePerSecond DWORD INTERNAL 4
HillClimbing_MaxSampleErrorPercent DWORD INTERNAL 15
HillClimbing_MaxWaveMagnitude DWORD INTERNAL 20
HillClimbing_SampleIntervalHigh DWORD INTERNAL 200
HillClimbing_SampleIntervalLow DWORD INTERNAL 10
HillClimbing_TargetSignalToNoiseRatio DWORD INTERNAL 300
HillClimbing_WaveHistorySize DWORD INTERNAL 8
HillClimbing_WaveMagnitudeMultiplier DWORD INTERNAL 100
HillClimbing_WavePeriod DWORD INTERNAL 4
Thread_UseAllCpuGroups Specifies if to automatically distribute thread across CPU Groups DWORD EXTERNAL 0
ThreadPool_DebugBreakOnWorkerStarvation Breaks into the debugger if the ThreadPool detects work queue starvation DWORD INTERNAL 0
ThreadPool_DisableStarvationDetection Disables the ThreadPool feature that forces new threads to be added when workitems run for too long DWORD INTERNAL 0
ThreadPool_EnableWorkerTracking Enables extra expensive tracking of how many workers threads are working simultaneously DWORD INTERNAL 0
ThreadPool_ForceMaxWorkerThreads Overrides the MaxThreads setting for the ThreadPool worker pool DWORD INTERNAL 0
ThreadPool_ForceMinWorkerThreads Overrides the MinThreads setting for the ThreadPool worker pool DWORD INTERNAL 0
ThreadPool_UnfairSemaphoreSpinLimit Maximum number of spins per processor a thread pool worker thread performs before waiting for work DWORD INTERNAL 0x32
ThreadpoolTickCountAdjustment DWORD INTERNAL 0

Tiered Compilation Configuration Knobs

Name Description Type Class Default Value Flags
TieredCompilation Enables tiered compilation DWORD EXTERNAL 1
TieredCompilation_Test_CallCounting Enabled by default (only activates when TieredCompilation is also enabled). If disabled immediately backpatches prestub, and likely prevents any tier1 promotion DWORD UNSUPPORTED 1
TieredCompilation_Test_OptimizeTier0 Use optimized codegen (normally used by tier1) in tier0 DWORD UNSUPPORTED 0
TieredCompilation_Tier1CallCountingDelayMs Delay in milliseconds since process startup or the last tier 0 JIT before call counting begins for tier 1 promotion. DWORD UNSUPPORTED 100
TieredCompilation_Tier1CallCountThreshold Number of times a method must be called after which it is promoted to tier 1. DWORD UNSUPPORTED 30

TypeLoader Configuration Knobs

Name Description Type Class Default Value Flags
TypeLoader_InjectInterfaceDuplicates Injects duplicates in interface map for all types. DWORD INTERNAL 0

Uncategorized Configuration Knobs

Name Description Type Class Default Value Flags
ActivatePatchSkip Allows an assert when ActivatePatchSkip is called DWORD INTERNAL 0 REGUTIL_default
AlwaysUseMetadataInterfaceMapLayout Used for debugging generic interface map layout. DWORD INTERNAL
AssertOnUnneededThis While the ConfigDWORD is unnecessary, the contained ASSERT should be kept. This may result in some work tracking down violating MethodDescCallSites. DWORD INTERNAL 0
AssertStacktrace DWORD INTERNAL 1 REGUTIL_default
clearNativeImageStress DWORD INTERNAL 0 REGUTIL_default
CPUFamily DWORD INTERNAL
CPUFeatures DWORD INTERNAL
DisableConfigCache Used to disable the "probabilistic" config cache, which walks through the appropriate config registry keys on init and probabilistically keeps track of which exist. DWORD EXTERNAL 0 REGUTIL_default
DisableStackwalkCache DWORD EXTERNAL
DoubleArrayToLargeObjectHeap Controls double[] placement DWORD UNSUPPORTED
DumpConfiguration Dumps runtime properties of xml configuration files to the log. DWORD INTERNAL 0
DumpOnClassLoad Dumps information about loaded class to log. STRING INTERNAL
ExpandAllOnLoad DWORD INTERNAL
ForcedRuntime Verify version of CLR loaded STRING INTERNAL
ForceRelocs DWORD INTERNAL 0 REGUTIL_default
GenerateLongJumpDispatchStubRatio Useful for testing VSD on AMD64 DWORD INTERNAL
HashStack DWORD INTERNAL 0 REGUTIL_default
HostManagerConfig DWORD INTERNAL (DWORD)-1
HostTestADUnload Allows setting Rude unload as default DWORD INTERNAL 0
HostTestThreadAbort DWORD INTERNAL 0
IgnoreDllMainReturn Don't check the return value of DllMain if this is set DWORD UNSUPPORTED 0 ConfigFile_ApplicationFirst
InvokeHalt Throws an assert when the given method is invoked through reflection. STRING INTERNAL
legacyNullReferenceExceptionPolicy DWORD UNSUPPORTED
legacyUnhandledExceptionPolicy DWORD UNSUPPORTED
MaxStackDepth DWORD INTERNAL
MaxStubUnwindInfoSegmentSize DWORD INTERNAL
MaxThreadRecord DWORD INTERNAL
MessageDebugOut DWORD INTERNAL 0
MscorsnLogging Enables strong name logging DWORD INTERNAL 0 REGUTIL_default
NativeImageRequire DWORD EXTERNAL 0 REGUTIL_default
NestedEhOom DWORD INTERNAL 0 REGUTIL_default
NO_SO_NOT_MAINLINE DWORD EXTERNAL 0 REGUTIL_default
NoGuiOnAssert DWORD INTERNAL INTERNAL_NoGuiOnAssert_Default REGUTIL_default
NoProcedureSplitting DWORD EXTERNAL 0 REGUTIL_default
NoStringInterning Disallows string interning. I see no value in it anymore. DWORD INTERNAL 1 REGUTIL_default
NotifyBadAppCfg Whether to show a message box for bad application config file. DWORD EXTERNAL
PauseOnLoad Stops in SystemDomain::init. I think it can be removed. DWORD INTERNAL
PerfAllocsSizeThreshold Log facility LF_GCALLOC logs object allocations. This flag controls which ones also log stacktraces. Predates ClrProfiler. DWORD INTERNAL 0x3FFFFFFF
PerfNumAllocsThreshold Log facility LF_GCALLOC logs object allocations. This flag controls which ones also log stacktraces. Predates ClrProfiler. DWORD INTERNAL 0x3FFFFFFF
PerfTypesToLog Log facility LF_GCALLOC logs object allocations. This flag controls which ones also log stacktraces. Predates ClrProfiler. STRING INTERNAL
Prepopulate1 DWORD EXTERNAL 1
PrestubGC STRING INTERNAL
PrestubHalt STRING INTERNAL
RestrictedGCStressExe STRING EXTERNAL
ReturnSourceTypeForTesting Allows returning the (internal only) source type of an IL to Native mapping for debugging purposes DWORD INTERNAL 0 REGUTIL_default
RSStressLog Allows turning on logging for RS startup DWORD UNSUPPORTED 0 REGUTIL_default
SaveThreadInfo DWORD INTERNAL
SaveThreadInfoMask DWORD INTERNAL
SBDumpOnNewIndex Used for Syncblock debugging. It's been a while since any of those have been used. DWORD INTERNAL 0
SBDumpOnResize Used for Syncblock debugging. It's been a while since any of those have been used. DWORD INTERNAL 0
SBDumpStyle Used for Syncblock debugging. It's been a while since any of those have been used. DWORD INTERNAL 0
ShimDatabaseVersion Force using shim database version in registry STRING UNSUPPORTED
SleepOnExit Used for lrak detection. I'd say deprecated by umdh. DWORD UNSUPPORTED 0
StubLinkerUnwindInfoVerificationOn DWORD INTERNAL
SuccessExit DWORD UNSUPPORTED 0 REGUTIL_default
SupressAllowUntrustedCallerChecks Disable APTCA DWORD INTERNAL 0
SymbolReadingPolicy Specifies when PDBs may be read DWORD EXTERNAL
TestDataConsistency Allows ensuring the left side is not holding locks (and may thus be in an inconsistent state) when inspection occurs DWORD UNSUPPORTED FALSE
ThreadGuardPages DWORD EXTERNAL 0 REGUTIL_default
Timeline DWORD EXTERNAL 0 REGUTIL_default
TotalStressLogSize Total stress log size in bytes. DWORD UNSUPPORTED
TraceIUnknown DWORD EXTERNAL
TraceWrap DWORD EXTERNAL
TURNOFFDEBUGINFO DWORD EXTERNAL
UseMethodDataCache Used during feature development; may now be removed. DWORD EXTERNAL FALSE
UseParentMethodData Used during feature development; may now be removed. DWORD EXTERNAL TRUE
VerifierOff DWORD INTERNAL
VerifyAllOnLoad DWORD EXTERNAL

Virtual call stubs Configuration Knobs

Name Description Type Class Default Value Flags
VirtualCallStubCollideMonoPct Used only when STUB_LOGGING is defined, which by default is not. DWORD INTERNAL 0 REGUTIL_default
VirtualCallStubCollideWritePct Used only when STUB_LOGGING is defined, which by default is not. DWORD INTERNAL 100 REGUTIL_default
VirtualCallStubDumpLogCounter Used only when STUB_LOGGING is defined, which by default is not. DWORD INTERNAL 0 REGUTIL_default
VirtualCallStubDumpLogIncr Used only when STUB_LOGGING is defined, which by default is not. DWORD INTERNAL 0 REGUTIL_default
VirtualCallStubLogging Worth keeping, but should be moved into "#ifdef STUB_LOGGING" blocks. This goes for most (or all) of the stub logging infrastructure. DWORD EXTERNAL 0 REGUTIL_default
VirtualCallStubMissCount Used only when STUB_LOGGING is defined, which by default is not. DWORD INTERNAL 100 REGUTIL_default
VirtualCallStubResetCacheCounter Used only when STUB_LOGGING is defined, which by default is not. DWORD INTERNAL 0 REGUTIL_default
VirtualCallStubResetCacheIncr Used only when STUB_LOGGING is defined, which by default is not. DWORD INTERNAL 0 REGUTIL_default

Watson Configuration Knobs

Name Description Type Class Default Value Flags
DisableWatsonForManagedExceptions Disable Watson and debugger launching for managed exceptions DWORD INTERNAL 0

Zap Configuration Knobs

Name Description Type Class Default Value Flags
DebugAssertOnMissedCOWPage DWORD INTERNAL 1
EnableEventLog Enable/disable use of EnableEventLogging mechanism DWORD EXTERNAL 0
EventNameFilter STRING INTERNAL
EventSourceFilter STRING INTERNAL
ReadyToRun Enable/disable use of ReadyToRun native code DWORD EXTERNAL 1
ReadyToRunExcludeList List of assemblies that cannot use Ready to Run images STRING EXTERNAL
ReadyToRunLogFile Name of file to log success/failure of using Ready to Run images STRING EXTERNAL
ZapBBInstr STRING INTERNAL REGUTIL_default
ZapBBInstrDir STRING EXTERNAL
ZapDisable DWORD EXTERNAL 0
ZapExclude STRING INTERNAL REGUTIL_default
ZapLazyCOWPagesEnabled DWORD INTERNAL 1
ZapOnly STRING INTERNAL REGUTIL_default
ZapRequire DWORD EXTERNAL
ZapRequireExcludeList STRING EXTERNAL
ZapRequireList STRING EXTERNAL
ZapSet STRING EXTERNAL REGUTIL_default

PAL Configuration Knobs

All the names below need to be prefixed by COMPlus_.

Name Description Type Default Value
DefaultStackSize Overrides the default stack size for secondary threads STRING 0
DbgEnableMiniDump If set to 1, enables this core dump generation. The default is NOT to generate a dump DWORD 0
DbgMiniDumpName If set, use as the template to create the dump path and file name. The pid can be placed in the name with %d. STRING _/tmp/coredump.%d_
DbgMiniDumpType If set to 1 generates MiniDumpNormal, 2 MiniDumpWithPrivateReadWriteMemory, 3 MiniDumpFilterTriage, 4 MiniDumpWithFullMemory DWORD 1
CreateDumpDiagnostics If set to 1, enables the createdump utilities diagnostic messages (TRACE macro) DWORD 0