The DDK’s master kernel-mode include file, ntddk.h, defines a pair of functions that are useful in debugging kernel-mode drivers. The DbgBreakPoint function inserts a breakpoint, and the DbgPrint function prints a formatted string to WinDbg . For debugging Win32 user-mode drivers, the Win32 API provides two similar functions, DebugBreak and OutputDebugString, which print to WinDbg.