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KASSERT(9)                 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 number
     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>.

NetBSD 7.1.2                  September 27, 2011                  NetBSD 7.1.2