Hardware Query Interfaces

uint_t cpc_npic(cpc_t *cpc);
uint_t cpc_caps(cpc_t *cpc);
void cpc_walk_events_all(cpc_t *cpc, void *arg,
          void (*action)(void *arg, const char *event));
void cpc_walk_events_pic(cpc_t *cpc, uint_t picno, void *arg, 
          void(*action)(void *arg, uint_t picno, const char *event));
void cpc_walk-attrs(cpc_t *cpc, void *arg,
          void (*action)(void *arg, const char *attr));

The cpc_npic() function returns the number of physical counters on the underlying processor.

The cpc_caps() function returns a uint_t parameter whose value is the result of the bitwise inclusive-OR operation performed on the capabilities that the underlying processor supports. There are two capabilities. The CPC_CAP_OVERFLOW_INTERRUPT capability enables the processor to generate an interrupt when a counter overflows. The CPC_CAP_OVERFLOW_PRECISE capability enables the processor to determine which counter generates an overflow interrupt.

The kernel maintains a list of the events that the underlying processor supports. Different physical counters on a single chip do not have to use the same list of events. The cpc_walk_events_all() function calls the the action() routine for each processor-supported event without regard to physical counter. The cpc_walk_events_pic() function calls the action() routine for each processor-supported event on a specific physical counter. Both of these functions pass the arg parameter uninterpreted from the caller to each invocation of the action() function.

The platform maintains a list of attributes that the underlying processor supports. These attributes enable access to advanced processor-specific features of the performance counters. The cpc_walk_attrs() function calls the action routine on each attribute name.