#ifndef _NTEXAPI_H
#if (PHNT_MODE != PHNT_MODE_KERNEL)

/**
 * The NtQueryBootOptions routine retrieves the current boot options.
 *
 * \param BootOptions A pointer to a buffer that receives the boot options.
 * \param BootOptionsLength A pointer to a variable that specifies the size of the buffer. On return, it contains the size of the data returned.
 * \return NTSTATUS Successful or errant status.
 */
NTSYSCALLAPI
NTSTATUS
NTAPI
NtQueryBootOptions(
    _Out_writes_bytes_opt_(*BootOptionsLength) PBOOT_OPTIONS BootOptions,
    _Inout_ PULONG BootOptionsLength
    );

#endif
#endif
View code on GitHub

#ifndef _NTZWAPI_H

NTSYSCALLAPI
NTSTATUS
NTAPI
ZwQueryBootOptions(
    _Out_writes_bytes_opt_(*BootOptionsLength) PBOOT_OPTIONS BootOptions,
    _Inout_ PULONG BootOptionsLength
    );

#endif
View code on GitHub