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

NAME

     device_printf, printf, snprintf, vprintf, vsnprintf, uprintf, ttyprintf, tprintf, aprint -- kernel formatted output conversion

SYNOPSIS

     #include <sys/systm.h>

     void
     device_printf(device_t, const char *format, ...);

     void
     printf(const char *format, ...);

     void
     printf_nolog(const char *format, ...);

     int
     snprintf(char *buf, size_t size, const char *format, ...);

     void
     vprintf(const char *format, va_list ap);

     int
     vsnprintf(char *buf, size_t size, const char *format, va_list ap);

     void
     uprintf(const char *format, ...);

     void
     ttyprintf(struct tty *tty, const char *format, ...);

     #include <sys/tprintf.h>

     tpr_t
     tprintf_open(struct proc *p);

     void
     tprintf(tpr_t tpr, const char *format, ...);

     void
     tprintf_close(tpr_t tpr);

     void
     aprint_normal(const char *format, ...);

     void
     aprint_naive(const char *format, ...);

     void
     aprint_verbose(const char *format, ...);

     void
     aprint_debug(const char *format, ...);

     void
     aprint_error(const char *format, ...);

     void
     aprint_normal_dev(device_t, const char *format, ...);

     void
     aprint_naive_dev(device_t, const char *format, ...);

     void
     aprint_verbose_dev(device_t, const char *format, ...);

     void
     aprint_debug_dev(device_t, const char *format, ...);

     void
     aprint_error_dev(device_t, const char *format, ...);

     void
     aprint_normal_ifnet(struct ifnet *, const char *format, ...);

     void
     aprint_naive_ifnet(struct ifnet *, const char *format, ...);

     void
     aprint_verbose_ifnet(struct ifnet *, const char *format, ...);

     void
     aprint_debug_ifnet(struct ifnet *, const char *format, ...);

     void
     aprint_error_ifnet(struct ifnet *, const char *format, ...);

     int
     aprint_get_error_count(void);

DESCRIPTION

     The printf() family of functions allows the kernel to send formatted messages to various output devices.  The functions printf() and
     vprintf() send formatted strings to the system console.  The device_printf() function is identical to printf(), except that it prefixes the
     log message with the corresponding device name.  The printf_nolog() function is identical to printf(), except it does not send the data to
     the system log.  The functions snprintf() and vsnprintf() write output to a string buffer.  These four functions work similarly to their user
     space counterparts, and are not described in detail here.

     The functions uprintf() and ttyprintf() send formatted strings to the current process's controlling tty and a specific tty, respectively.

     The tprintf() function sends formatted strings to a process's controlling tty, via a handle of type tpr_t.  This allows multiple write opera-
     tions to the tty with a guarantee that the tty will be valid across calls.  A handle is acquired by calling tprintf_open() with the target
     process as an argument.  This handle must be closed with a matching call to tprintf_close().

     The functions aprint_normal(), aprint_naive(), aprint_verbose(), aprint_debug(), and aprint_error() are intended to be used to print
     autoconf(9) messages.  Their verbosity depends on flags set in the boothowto variable, through options passed during bootstrap; see
     boothowto(9) and Interactive mode in boot(8):

     AB_SILENT	 silent mode, enabled by boot -z.

     AB_QUIET	 quiet mode, enabled by boot -q.

     AB_VERBOSE  verbose mode, enabled by boot -v.

     AB_DEBUG	 debug mode, enabled by boot -x.

     The aprint_*() functions have the following behaviour, based on the above mentioned flags:

     aprint_normal()	 Sends to the console unless AB_QUIET is set.  Always sends to the log.

     aprint_naive()	 Sends to the console only if AB_QUIET is set.	Never sends to the log.

     aprint_verbose()	 Sends to the console only if AB_VERBOSE is set.  Always sends to the log.

     aprint_debug()	 Sends to the console and the log only if AB_DEBUG is set.

     aprint_error()	 Like aprint_normal(), but also keeps track of the number of times called.  This allows a subsystem to report the number
			 of errors that occurred during a quiet or silent initialization phase.

     For the aprint_*() functions there are two additional families of functions with the suffixes _dev and _ifnet which work like their counter-
     parts without the suffixes, except that they take a device_t and struct ifnet *, respectively, as first argument, and prefix the log message
     with the corresponding device or interface name.

     The aprint_get_error_count() function reports the number of errors and resets the counter to 0.

     If AB_SILENT is set, none of the autoconfiguration message printing routines send output to the console.  The AB_VERBOSE and AB_DEBUG flags
     override AB_SILENT.

RETURN VALUES

     The snprintf() and vsnprintf() functions return the number of characters placed in the buffer buf.  This is different to the user-space func-
     tions of the same name.

     The tprintf_open() function returns NULL if no terminal handle could be acquired.

SEE ALSO

     printf(1), printf(3), snprintb(3), boot(8), autoconf(9), boothowto(9)

CODE REFERENCES

     sys/kern/subr_prf.c

HISTORY

     The sprintf() and vsprintf() unsized string formatting functions are supported for compatibility only, and are not documented here.  New code
     should use the size-limited snprintf() and vsnprintf() functions instead.

     In NetBSD 1.5 and earlier, printf() supported more format strings than the user space printf().  These nonstandard format strings are no
     longer supported.	For the functionality provided by the former %b format string, see snprintb(3).

     The aprint_normal(), aprint_naive(), aprint_verbose(), and aprint_debug() functions first appeared in BSD/OS.

BUGS

     The uprintf() and ttyprintf() functions should be used sparingly, if at all.  Where multiple lines of output are required to reach a
     process's controlling terminal, tprintf() is preferred.

BSD
								 January 21, 2011							       BSD