IRQL

#define PASSIVE_LEVEL 0             // Passive release level

#define LOW_LEVEL 0                 // Lowest interrupt level

#define APC_LEVEL 1                 // APC interrupt level

#define DISPATCH_LEVEL 2            // Dispatcher level

#define CMCI_LEVEL 5                // CMCI handler level

#define PROFILE_LEVEL 27            // timer used for profiling.

#define CLOCK1_LEVEL 28             // Interval clock 1 level - Not used on x86

#define CLOCK2_LEVEL 28             // Interval clock 2 level

#define IPI_LEVEL 29                // Interprocessor interrupt level

#define POWER_LEVEL 30              // Power failure level

#define HIGH_LEVEL 31               // Highest interrupt level

Dispatch Routine IRQL and Thread Context

The following table summarizes the IRQL and thread context requirements for file system filter driver dispatch routines.

Dispatch routine	Caller's IRQL:	Caller's thread context:
Cleanup	PASSIVE_LEVEL	Nonarbitrary
Close	APC_LEVEL	Arbitrary
Create	PASSIVE_LEVEL	Nonarbitrary
DeviceControl (except paging I/O)	PASSIVE_LEVEL	Nonarbitrary
DeviceControl (paging I/O path)	APC_LEVEL	Arbitrary
DirectoryControl	APC_LEVEL	Arbitrary
FlushBuffers	PASSIVE_LEVEL	Nonarbitrary
FsControl (except paging I/O)	PASSIVE_LEVEL	Nonarbitrary
FsControl (paging I/O path)	APC_LEVEL	Arbitrary
LockControl	PASSIVE_LEVEL	Nonarbitrary
PnP	PASSIVE_LEVEL	Arbitrary
QueryEa	PASSIVE_LEVEL	Nonarbitrary
QueryInformation	PASSIVE_LEVEL	Nonarbitrary
QueryQuota	PASSIVE_LEVEL	Nonarbitrary
QuerySecurity	PASSIVE_LEVEL	Nonarbitrary
QueryVolumeInfo	PASSIVE_LEVEL	Nonarbitrary
Read (except paging I/O)	PASSIVE_LEVEL	Nonarbitrary
Read (paging I/O path)	APC_LEVEL	Arbitrary
SetEa	PASSIVE_LEVEL	Nonarbitrary
SetInformation	PASSIVE_LEVEL	Nonarbitrary
SetQuota	PASSIVE_LEVEL	Nonarbitrary
SetSecurity	PASSIVE_LEVEL	Nonarbitrary
SetVolumeInfo	PASSIVE_LEVEL	Nonarbitrary
Shutdown	PASSIVE_LEVEL	Arbitrary
Write (except paging I/O)	PASSIVE_LEVEL	Nonarbitrary
Write (paging I/O path)	APC_LEVEL	Arbitrary