DevHlp_RegisterKDD

Undocumented.

Remarks

There is a more or less undocumented Device Helper (DevHlp_RegisterKDD, function code 0x83) that allows a remote debugger to send commands to the debug kernel and receive the returns and also events. For example, this Device Helper is used by KDBNET.SYS to support debugging via UDP network connection. The "Control Programming Guide and Reference" contains a chapter "Kernel Debugger Communications Protocol" that sheds some light on the commands you can send and also the returns and events you will receive.

At one point in time I dug into this stuff to find out what registers are used in the Device Helper and what format the input and output buffers have to be. Unfortunately I lost my notes (they were incomplete anyway).

You'll need to delve into KDBNET.SYS and do some reverse engineering.