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⟩.

September 27, 2011 | NetBSD 8.2