KernInterruptLevel

Dereferences to the linear address pointing to the interrupt level.

Is the equivalent of what DevHelp GetDOSVar returns for index DHGETDOSV_INTERRUPTLEV.

The _KernInterruptLevel global variable is pointing to a 1-byte value that contains the current interrupt level if the code is currently executing in interrupt context. It contains 0xFF if the code is currently executing in task context.