_POOL_TYPE enumeration

Description

The POOL_TYPE enumeration type specifies the type of system memory to allocate.

Syntax

typedef enum _POOL_TYPE {
    NonPagedPool,
    NonPagedPoolExecute = NonPagedPool,
    PagedPool,
    NonPagedPoolMustSucceed = NonPagedPool + 2,
    DontUseThisType,
    NonPagedPoolCacheAligned = NonPagedPool + 4,
    PagedPoolCacheAligned,
    NonPagedPoolCacheAlignedMustS = NonPagedPool + 6,
    MaxPoolType,
    NonPagedPoolBase = 0,
    NonPagedPoolBaseMustSucceed = NonPagedPoolBase + 2,
    NonPagedPoolBaseCacheAligned = NonPagedPoolBase + 4,
    NonPagedPoolBaseCacheAlignedMustS = NonPagedPoolBase + 6,
    NonPagedPoolSession = 32,
    PagedPoolSession = NonPagedPoolSession + 1,
    NonPagedPoolMustSucceedSession = PagedPoolSession + 1,
    DontUseThisTypeSession = NonPagedPoolMustSucceedSession + 1,
    NonPagedPoolCacheAlignedSession = DontUseThisTypeSession + 1,
    PagedPoolCacheAlignedSession = NonPagedPoolCacheAlignedSession + 1,
    NonPagedPoolCacheAlignedMustSSession = PagedPoolCacheAlignedSession + 1,
    NonPagedPoolNx = 512,
    NonPagedPoolNxCacheAligned = NonPagedPoolNx + 4,
    NonPagedPoolSessionNx = NonPagedPoolNx + 32,

} POOL_TYPE;

Constants

NonPagedPool

Nonpaged pool, which is nonpageable system memory. Nonpaged pool can be accessed from any IRQL, but it is a scarce resource and drivers should allocate it only when necessary.

System memory allocated with the NonPagedPool pool type is executable. For more information, see the description of the NonPagedPoolExecute pool type.

Starting with Windows 8, drivers should allocate most or all of their nonpaged memory from the no-execute (NX) nonpaged pool instead of the executable nonpaged pool. For more information, see the description of the NonPagedPoolNx pool type.

NonPagedPoolExecute

Starting with Windows 8, NonPagedPoolExecute is an alternate name for the NonPagedPool value. This value indicates that the allocated memory is to be nonpaged and executable—that is, instruction execution is enabled in this memory. To port a driver from an earlier version of Windows, you should typically replace all or most instances of the NonPagedPool name in the driver source code with NonPagedPoolNx. Avoid replacing instances of the NonPagedPool name with NonPagedPoolExecute except in cases in which executable memory is explicitly required. For more information, see No-Execute (NX) Nonpaged Pool.

PagedPool

Paged pool, which is pageable system memory. Paged pool can only be allocated and accessed at IRQL < DISPATCH_LEVEL.

NonPagedPoolMustSucceed

This value is for internal use only, and is allowed only during system startup. Drivers must not specify this value at times other than system startup, because a "must succeed" request crashes the system if the requested memory size is unavailable.

DontUseThisType

Reserved for system use.

NonPagedPoolCacheAligned

Nonpaged pool, aligned on processor cache boundaries. This value is for internal use only.

PagedPoolCacheAligned

Paged pool, aligned on processor cache boundaries. This value is for internal use only.

NonPagedPoolCacheAlignedMustS

This value is for internal use only, and is allowed only during system startup. It is the cache-aligned equivalent of NonPagedPoolMustSucceed.

MaxPoolType

Reserved for system use.

NonPagedPoolBase

Reserved for system use.

NonPagedPoolBaseMustSucceed

Reserved for system use.

NonPagedPoolBaseCacheAligned

Reserved for system use.

NonPagedPoolBaseCacheAlignedMustS

Reserved for system use.

NonPagedPoolSession

Deprecated. Do not use.

PagedPoolSession

Deprecated. Do not use.

NonPagedPoolMustSucceedSession

Deprecated. Do not use.

DontUseThisTypeSession

Deprecated. Do not use.

NonPagedPoolCacheAlignedSession

Deprecated. Do not use.

PagedPoolCacheAlignedSession

Deprecated. Do not use.

NonPagedPoolCacheAlignedMustSSession

Deprecated. Do not use.

NonPagedPoolNx

No-execute (NX) nonpaged pool. This pool type is available starting with Windows 8. In contrast to the nonpaged pool designated by NonPagedPool, which allocates executable memory, the NX nonpaged pool allocates memory in which instruction execution is disabled. For more information, see No-Execute (NX) Nonpaged Pool.

Nonpaged pool can be accessed from any IRQL, but it is a scarce resource and drivers should allocate it only when necessary.

NonPagedPoolNxCacheAligned

NX nonpaged pool, aligned on processor cache boundaries. This value is reserved for exclusive use by the operating system.

NonPagedPoolSessionNx

Reserved for exclusive use by the operating system.

See also

ExAllocatePoolWithQuotaTag

ExAllocatePoolWithTag

ExAllocatePoolWithTagPriority

ExInitializeLookasideListEx

ExInitializeNPagedLookasideList

ExInitializePagedLookasideList

LookasideListAllocateEx

SeAssignSecurity

SeAssignSecurityEx