Kernel Functions for Drivers         ddiintrgethilevelpri(9F)



NAME
     ddiintrgethilevelpri - get minimum priority level for  a
     high-level interrupt

SYNOPSIS
     #include 
     #include 
     #include 
     #include 

     int ddiintrgethilevelpri(void);


INTERFACE LEVEL
     Solaris DI specific (Solaris DI).

DESCRIPTION
     Upon a  successful  return,  the  ddiintrgethilevelpri()
     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
     ddiintrgetpri(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 cir-
     cular  buffer  and  schedule  a  soft  interrupt  by calling
     ddiintrtriggersoftint(). The circular buffer can be  pro-
     tected by using a mutex that is properly initialized for the
     interrupt handler.


     The ddiintrgethilevelpri() function can be  used  before
     calling  ddiintraddhandler() 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 ddiintrgethilevelpri() function to test the
     type of interrupt handler that can be used.




SunOS 5.11          Last change: 07 Apr 2005                    1






Kernel Functions for Drivers         ddiintrgethilevelpri(9F)



RETURN VALUES
     The ddiintrgethilevelpri() function returns the priority
     value for a high-level interrupt.

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

ATRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:



     
           ATRIBUTE TYPE               ATRIBUTE VALUE       
    
     Interface Stability          Committed                   
    


SEE ALSO
     attributes(5), ddiintraddhandler(9F), ddiintralloc(9F),
     ddiintrenable(9F),                   ddiintrgetpri(9F),
     ddiintrtriggersoftint(9F), mutex(9F)


     Writing Device Drivers



























SunOS 5.11          Last change: 07 Apr 2005                    2