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

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

#include <sys/types.h>
#include <sys/conf.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
int ddi_intr_get_hilevel_pri(void);

illumos DDI specific (illumos DDI).

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_softint(). 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.

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

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

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

ATTRIBUTE TYPE ATTRIBUTE VALUE
Interface Stability Committed

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

April 7, 2005 OmniOS