B.3.4.1 splstr and splx (Not Supported)
In the UNIX kernel, STREAMS drivers and modules use the spl* functions (splstr and splx) to implement critical sections, so that put and service procedures are not preempted by interrupt routines and procedures triggered by timeout. In the Windows NT kernel, it is not sufficient for a STREAMS stack to protect its critical sections by raising its interrupt level. Hence, STREAMS does not provide the spl* functions. STREAMS stacks must be rewritten to use spin locks.