Those writing device drivers, or are interested in seeing outputs from a kernel driver’s calls to the KdPrint macro or the DbgPrint function may find that the messages don’t appear on Windows Vista or newer versions of Windows. Even when using a tool such as DebugView (from SysInternals), running with administrative privileges, with kernel capture turned on, nothing seem to appear from expected drivers:
To set the correct level, a key named Debug Print Filter must be added (it does not exist by default) under HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager
In that key, values can be added corresponding to a level that we want to see messages for (error, warning, trace, info). It turns out that the “default” old behavior provided by KdPrint/DbgPrint is to use the “Info” level, which has a value of 3, and this signifies the bit that needs to be set to one, so the actual number is 2 to the third power which is 8. Furthermore, the correct “component” name needs to be specified, and for KdPrint/DbgPrint it’s named “DEFAULT” (note, it must have capital letters).
This leads to the following setting in the registry:
Once that’s set, a restart is required for the setting to take effect. Then opening DebugView and enabling kernel output capture will show KdPrint/DbgPrint calls.