#ifndef _NTEXAPI_H
#if (PHNT_MODE != PHNT_MODE_KERNEL)

NTSYSCALLAPI
NTSTATUS
NTAPI
NtSetSystemInformation(
    _In_ SYSTEM_INFORMATION_CLASS SystemInformationClass,
    _In_reads_bytes_opt_(SystemInformationLength) PVOID SystemInformation,
    _In_ ULONG SystemInformationLength
    );

#endif
#endif
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#ifndef _NTZWAPI_H

NTSYSCALLAPI
NTSTATUS
NTAPI
ZwSetSystemInformation(
    _In_ SYSTEM_INFORMATION_CLASS SystemInformationClass,
    _In_reads_bytes_opt_(SystemInformationLength) PVOID SystemInformation,
    _In_ ULONG SystemInformationLength
    );

#endif
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This function is documented in Windows SDK.

NtSetSystemInformation is used to set some inaccessible KernelMode variables. See also NtQuerySystemInformation.

SystemInformationClass

Information class described in SYSTEM_INFORMATION_CLASS.

SystemInformation

Pointer to data buffer to set.

SystemInformationLength

Length of information in SystemInformation buffer, in bytes.

Documented by

Sven B. Schreiber
Tomasz Nowak