KASSERT(9)						   BSD Kernel Developer's Manual						KASSERT(9)

NAME

     KASSERT, KASSERTMSG, KDASSERT, KDASSERTMSG -- kernel expression verification macros

SYNOPSIS

     void
     KASSERT(expression);

     void
     KASSERTMSG(expression, format, ...);

     void
     KDASSERT(expression);

     void
     KDASSERTMSG(expression, format, ...);

DESCRIPTION

     These machine independent assertion-checking macros cause a kernel panic(9) if the given expression evaluates to false.  Two compile-time
     options(4) define the behavior of the checks.

       1.   The KASSERT() and KASSERTMSG() tests are included only in kernels compiled with the DIAGNOSTIC configuration option.  In a kernel that
	    does not have this configuration option, the macros are defined to be no-ops.

       2.   The KDASSERT() and KDASSERTMSG() tests are included only in kernels compiled with the DEBUG configuration option.  The KDASSERT() and
	    KASSERT() macros are identical except for the controlling option (DEBUG vs DIAGNOSTIC).  Basically, KASSERT() should be used for
	    light-weight checks and KDASSERT() should be used for heavier ones.

     Callers should not rely on the side effects of expression because, depending on the kernel compile options mentioned above, expression might
     not be evaluated at all.

     The panic message will display the style of assertion (debugging vs. diagnostic), the expression that failed and the filename, and line num-
     ber the failure happened on.  The KASSERTMSG() and KDASSERTMSG() macros append to the panic(9) format string the message specified by format
     and its subsequent arguments, similar to printf(9) functions.

SEE ALSO

     config(1), options(4), CTASSERT(9), panic(9), printf(9)

AUTHORS

     These macros were written by Chris G. Demetriou <cgd@netbsd.org>.

BSD
								September 27, 2011							       BSD