kassert(9) [netbsd man page]

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

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

NAME

     panic -- Bring down system on fatal error

SYNOPSIS

     #include <sys/types.h>
     #include <sys/systm.h>

     void
     vpanic(const char *fmt, va_list ap);

     void
     panic(const char *fmt, ...);

DESCRIPTION

     The panic() and vpanic() functions terminate the NetBSD system.  The message fmt is a printf(3) style format string which is printed to the
     console and saved in the variable panicstr for later retrieval via core dump inspection.  A newline character is added at the end automati-
     cally, and is thus not needed in the format string.

     If a kernel debugger is installed, control is passed to it after the message is printed.  If the kernel debugger is ddb(4), control may be
     passed to it, depending on the value of ddb.onpanic.  See options(4) for more details on setting ddb.onpanic.  If control is not passed
     through to ddb(4), a ddb(4)-specific function is used to print the kernel stack trace, and then control returns to panic().

     If control remains in panic(), an attempt is made to save an image of system memory on the configured dump device.

     If during the process of handling the panic, panic() is called again (from the filesystem synchronization routines, for example), the system
     is rebooted immediately without synchronizing any filesystems.

     panic() is meant to be used in situations where something unexpected has happened and it is difficult to recover the system to a stable
     state, or in situations where proceeding might make the things worse, leading to data corruption/loss.  It is not meant to be used in scenar-
     ios where the system could easily ignore and/or isolate the condition/subsystem and proceed.

     In general developers should try to reduce the number of panic() calls in the kernel to improve stability.

RETURN VALUES

     The panic() function does not return.

SEE ALSO

     sysctl(3), ddb(4), ipkdb(4), options(4), savecore(8), swapctl(8), sysctl(8)

BSD
								September 29, 2011							       BSD