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MEMORY_BASIC_INFORMATION structure (winnt.h)

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Contains information about a range of pages in the virtual address space of a process. The VirtualQuery and VirtualQueryEx functions use this structure.

Syntax

typedef struct _MEMORY_BASIC_INFORMATION {
  PVOID  BaseAddress;
  PVOID  AllocationBase;
  DWORD  AllocationProtect;
  WORD   PartitionId;
  SIZE_T RegionSize;
  DWORD  State;
  DWORD  Protect;
  DWORD  Type;
} MEMORY_BASIC_INFORMATION, *PMEMORY_BASIC_INFORMATION;

Members

BaseAddress

A pointer to the base address of the region of pages.

AllocationBase

A pointer to the base address of a range of pages allocated by the VirtualAlloc function. The page pointed to by the BaseAddress member is contained within this allocation range.

AllocationProtect

The memory protection option when the region was initially allocated. This member can be one of the memory protection constants or 0 if the caller does not have access.

PartitionId

RegionSize

The size of the region beginning at the base address in which all pages have identical attributes, in bytes.

State

The state of the pages in the region. This member can be one of the following values.

State Meaning
MEM_COMMIT
0x1000
 Indicates committed pages for which physical storage has been allocated, either in memory or in the paging file on disk.
MEM_FREE
0x10000
 Indicates free pages not accessible to the calling process and available to be allocated. For free pages, the information in the AllocationBase, AllocationProtect, Protect, and Type members is undefined.
MEM_RESERVE
0x2000
 Indicates reserved pages where a range of the process's virtual address space is reserved without any physical storage being allocated. For reserved pages, the information in the Protect member is undefined.

Protect

The access protection of the pages in the region. This member is one of the values listed for the AllocationProtect member.

Type

The type of pages in the region. The following types are defined.

Type Meaning
MEM_IMAGE
0x1000000
 Indicates that the memory pages within the region are mapped into the view of an image section.
MEM_MAPPED
0x40000
 Indicates that the memory pages within the region are mapped into the view of a section.
MEM_PRIVATE
0x20000
 Indicates that the memory pages within the region are private (that is, not shared by other processes).

Remarks

To enable a debugger to debug a target that is running on a different architecture (32-bit versus 64-bit), use one of the explicit forms of this structure.

typedef struct _MEMORY_BASIC_INFORMATION32 {
    DWORD BaseAddress;
    DWORD AllocationBase;
    DWORD AllocationProtect;
    DWORD RegionSize;
    DWORD State;
    DWORD Protect;
    DWORD Type;
} MEMORY_BASIC_INFORMATION32, *PMEMORY_BASIC_INFORMATION32;

typedef struct DECLSPEC_ALIGN(16) _MEMORY_BASIC_INFORMATION64 {
    ULONGLONG BaseAddress;
    ULONGLONG AllocationBase;
    DWORD     AllocationProtect;
    DWORD     __alignment1;
    ULONGLONG RegionSize;
    DWORD     State;
    DWORD     Protect;
    DWORD     Type;
    DWORD     __alignment2;
} MEMORY_BASIC_INFORMATION64, *PMEMORY_BASIC_INFORMATION64;

Requirements

Requirement Value
Minimum supported client Windows XP [desktop apps only]
Minimum supported server Windows Server 2003 [desktop apps only]
Header winnt.h (include Windows.h)

See also

VirtualAlloc

VirtualQuery

VirtualQueryEx