DbgPrintEx - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers
#ifndef _NTDBG_H

NTSYSAPI
ULONG
STDAPIVCALLTYPE
DbgPrintEx(
    _In_ ULONG ComponentId,
    _In_ ULONG Level,
    _In_z_ _Printf_format_string_ PCSTR Format,
    ...
    );

#endif

View code on GitHub

This function is documented in Windows Driver Kit.