ddi_intr_get_hilevel_pri(9F)				   Kernel Functions for Drivers 			      ddi_intr_get_hilevel_pri(9F)

NAME

       ddi_intr_get_hilevel_pri - get minimum priority level for a high-level interrupt

SYNOPSIS

       #include <sys/types.h>
       #include <sys/conf.h>
       #include <sys/ddi.h>
       #include <sys/sunddi.h>

       int ddi_intr_get_hilevel_pri(void);

INTERFACE LEVEL

       Solaris DDI specific (Solaris DDI).

DESCRIPTION

       Upon a successful return, the ddi_intr_get_hilevel_pri() function returns the minimum priority level for a high-level interrupt. The return
       priority value can be used to compare to other priority values, such as those returned from ddi_intr_get_pri(9F), to determine if  a  given
       interrupt priority is a high-level interrupt.

       High-level  interrupts  must be handled without using system services that manipulate thread or process states, because such interrupts are
       not blocked by the scheduler.

       In addition, high-level interrupt handlers must take care to do a minimum of work because they cannot be preempted.

       A typical high-level interrupt handler puts data into a circular buffer and schedule a soft  interrupt  by  calling  ddi_intr_trigger_soft-
       int(). The circular buffer can be protected by using a mutex that is properly initialized for the interrupt handler.

       The ddi_intr_get_hilevel_pri() function can be used before calling ddi_intr_add_handler() to help determine which type of interrupt handler
       can be used. Most device drivers are designed with the knowledge that supported devices always  generate  low  level  interrupts.  On  some
       machines,  however,  interrupts	are  high-level  above the scheduler level and on other machines they are not. Devices such as those those
       using SBus interrupts or VME bus level 6 or 7 interrupts must use the ddi_intr_get_hilevel_pri() function to test  the  type  of  interrupt
       handler that can be used.

RETURN VALUES

       The ddi_intr_get_hilevel_pri() function returns the priority value for a high-level interrupt.

CONTEXT

       The ddi_intr_get_hilevel_pri() function can be called from either user or kernel non-interrupt context.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Committed 		   |
       +-----------------------------+-----------------------------+

SEE ALSO

       attributes(5),	ddi_intr_add_handler(9F),  ddi_intr_alloc(9F),	ddi_intr_enable(9F),  ddi_intr_get_pri(9F),  ddi_intr_trigger_softint(9F),
       mutex(9F)

       Writing Device Drivers

SunOS 5.11							    07 Apr 2005 				      ddi_intr_get_hilevel_pri(9F)