softintr(9) - NetBSD Manual Pages

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SOFTINTR(9)            NetBSD Kernel Developer's Manual            SOFTINTR(9)


NAME

     softintr, softintr_establish, softintr_disestablish, softintr_schedule --
     machine-independent software interrupt framework


SYNOPSIS

     #include <machine/intr.h>

     void *
     softintr_establish(int level, void (*fun)(void *), void *arg);

     void
     softintr_disestablish(void *cookie);

     void
     softintr_schedule(void *cookie);


DESCRIPTION

     The NetBSD machine-independent software interrupt framework is designed
     to provide a generic software interrupt mechanism which can be used any
     time a low-priority callback is needed.  It allows dynamic registration
     of software interrupts for loadable drivers and protocol stacks, priori-
     tization and fair queueing of software interrupts, and allows machine-
     dependent optimizations to reduce cost and code complexity.

     In order to provide this framework, the machine-dependent
     <machine/types.h> must define the __HAVE_GENERIC_SOFT_INTERRUPTS symbol
     (without a value), furthermore, the machine-dependent <machine/intr.h>
     include file must provide prototypes for the softintr functions and must
     provide definitions of several constants which define software interrupt
     priority levels (IPLs):

     IPL_SOFTCLOCK   The software IPL for software clock interrupts (i.e.,
                     softclock()).

     IPL_SOFTNET     The software IPL for network callbacks.

     IPL_SOFTSERIAL  The software IPL for serial driver callbacks.

     Other constants of the form IPL_SOFT* are reserved for future use by this
     framework.

     The following is a brief description of each function in the framework:

     softintr_establish()     Register a software interrupt at level level,
                              which will call the function fun with one argu-
                              ment, arg.  It may allocate a machine-specific
                              data structure.  If successful,
                              softintr_establish() returns a non-NULL opaque
                              cookie which can be used as an argument to
                              softintr_schedule() or softintr_disestablish().
                              If for some reason it does not succeed, it
                              returns NULL.

     softintr_disestablish()  Deallocate a software interrupt previously allo-
                              cated by a call to softintr_establish().

     softintr_schedule()      Schedule a software interrupt previously allo-
                              cated by a call to softintr_establish() to be
                              executed as soon as that software interrupt is
                              unblocked.  This function may assume that the
                              interrupt is currently blocked, so it need not
                              check to see if the interrupt needs to be exe-
                              cuted immediately.  softintr_schedule() can
                              safely be called multiple times before the call-
                              back routine is invoked.


SEE ALSO

     spl(9)


HISTORY

     The NetBSD machine-independent software interrupt framework was designed
     in 1997 and was implemented by one port in NetBSD 1.3.  However, it did
     not gain wider implementation until NetBSD 1.5.


AUTHORS

     The NetBSD machine-independent software interrupt framework was designed
     by Charles Hannum <mycroft@NetBSD.org>.

NetBSD 4.0                       May 30, 2000                       NetBSD 4.0