for that argument. This will allow DDB to detect the broad category of
reason why the debugger has been entered, which it can use for the
purposes of deciding which DDB script to run.
Assign approximate why values to all current consumers of the
kdb_enter() interface.
DDB when the interrupt button (aka the "programmer's switch") is pressed.
This isn't unfortunately an NMI, but it's a handy way to get into DDB
quickly if needed.
