KPRINTF(9) BSD Kernel Developer's Manual KPRINTF(9)NAME
kprintf, ksprintf, ksnprintf, kvprintf, kvsprintf, kvsnprintf,
krateprintf, tprintf, uprintf, log — formatted output conversion
SYNOPSIS
#include <sys/types.h>
#include <sys/systm.h>
int
kprintf(const char *format, ...);
int
ksprintf(char *str, const char *format, ...);
int
ksnprintf(char *str, size_t size, const char *format, ...);
int
kvprintf(const char *format, __va_list ap);
int
kvsprintf(char *str, const char *format, __va_list ap);
int
kvsnprintf(char *str, size_t size, const char *format, __va_list ap);
void
krateprintf(struct krate *rate, const char *format, ...);
int
tprintf(struct proc *p, int pri, const char *format, ...);
int
uprintf(const char *format, ...);
#include <sys/syslog.h>
int
log(int pri, const char *format, ...);
DESCRIPTION
The kprintf family of functions are similar to the printf(3) family of
functions. The different functions each use a different output stream.
The uprintf() function outputs to the current process' controlling tty,
while kprintf(), ksprintf(), ksnprintf(), kvprintf(), kvsprintf() and
kvsnprintf() write to the console as well as to the logging facility.
The tprintf() function outputs to the tty associated with the process p
and the logging facility if pri is not -1. The log() function sends the
message to the kernel logging facility, using the log level as indicated
by pri.
Each of these related functions use the format, str, size and va parame‐
ters in the same manner as printf(3). However, the kprintf functions add
two other conversion specifiers to format:
The %b identifier expects two arguments: an int and a char *. These are
used as a register value and a print mask for decoding bitmasks. The
print mask is made up of two parts: the base and the arguments. The base
value is the output base expressed as an integer value; for example, \10
gives octal and \20 gives hexadecimal. The arguments are made up of a
sequence of bit identifiers. Each bit identifier begins with an integer
value which is the number of the bit (starting from 1) this identifier
describes. The rest of the identifier is a string of characters contain‐
ing the name of the bit. The string is terminated by either the bit num‐
ber at the start of the next bit identifier or NUL for the last bit iden‐
tifier.
The %D identifier is meant to assist in hexdumps. It requires two argu‐
ments: a u_char * pointer and a char * string. The memory pointed to be
the pointer is output in hexadecimal one byte at a time. The string is
used as a delimiter between individual bytes. If present, a width direc‐
tive will specify the number of bytes to display. By default, 16 bytes
of data are output.
The log() function uses syslog(3) level values LOG_DEBUG through
LOG_EMERG for its pri parameter (mistakenly called ‘priority’ here).
Alternatively, if a pri of -1 is given, the message will be appended to
the last log message started by a previous call to log(). As these mes‐
sages are generated by the kernel itself, the facility will always be
LOG_KERN.
The krateprintf() function is a rate controlled version of kprintf().
The freq member of the struct krate pointed to by rate must be initial‐
ized with the desired reporting frequency. A freq of 0 will result in no
output. Initializing count to a negative value allows an initial burst.
RETURN VALUES
The kprintf(), ksprintf(), ksnprintf(), kvprintf(), kvsprintf(),
kvsnprintf(), tprintf(), uprintf(), and log() functions return the number
of characters displayed.
EXAMPLES
This example demonstrates the use of the %b and %D conversion specifiers.
The function
void
kprintf_test(void)
{
kprintf("reg=%b\n", 3, "\10\2BITTWO\1BITONE\n");
kprintf("out: %4D\n", "AAAA", ":");
}
will produce the following output:
reg=3<BITTWO,BITONE>
out: 41:41:41:41
The call
log(LOG_DEBUG, "%s%d: been there.\n", sc->sc_name, sc->sc_unit);
will add the appropriate debug message at priority “kern.debug” to the
system log.
SEE ALSOprintf(3), syslog(3)BSD July 17, 2008 BSD
