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
Thepanic()
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 automatically, 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 things worse, leading to data
corruption and/or loss. It is not meant to be used in scenarios 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 never returns.
SEE ALSO
sysctl(3), ddb(4), options(4), savecore(8), swapctl(8), sysctl(8)