1.\" Copyright (c) 2001 John H. Baldwin <jhb@FreeBSD.org> 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD: src/share/man/man9/ktr.9,v 1.8 2005/03/08 01:37:36 hmp Exp $ 26.\" 27.Dd July 16, 2011 28.Dt KTR 9 29.Os 30.Sh NAME 31.Nm KTR_INFO_MASTER , 32.Nm KTR_INFO_MASTER_EXTERN , 33.Nm KTR_INFO , 34.Nm KTR_LOG 35.Nd kernel tracing facility 36.Sh SYNOPSIS 37.In sys/ktr.h 38.Vt "extern int ktr_entries" ; 39.Vt "extern int ktr_verbose" ; 40.Vt "extern struct ktr_entry *ktr_buf[MAXCPU]" ; 41.Fn KTR_INFO_MASTER "master" 42.Fn KTR_INFO_MASTER_EXTERN "master" 43.Fn KTR_INFO "compile" "master" "name" "maskbit" "format" "datasize" 44.Fn KTR_LOG "info" "arg ..." 45.Sh DESCRIPTION 46The 47.Nm ktr 48facility provides a circular buffer of events that can be logged in a 49.Xr kprintf 9 50style fashion. 51These events can then be dumped with 52.Xr ddb 4 , 53.Xr gdb 1 54or 55.Xr ktrdump 8 . 56.Pp 57.Fn KTR_INFO_MASTER 58declares a new master variable 59.Dv ktr Ns _ Ns Fa master Ns _ Ns Dv enable 60that is used to turn on and off event logging. 61.Fn KTR_INFO_MASTER_EXTERN 62is a convenience macro for declaring a master variable 63.Sy extern . 64.Pp 65The 66.Fn KTR_INFO 67macro registers a new event 68.Fa name 69that will be controlled by the 70.Fa master 71enable variable. 72Code for logging this event will be compiled in when 73.Fa compile 74is defined. 75The 76.Fa format 77argument is a limited (i.e.\& only integral types, no formatting) 78.Xr kprintf 9 79style format string used to build the text of the event log message while 80.Fa datasize 81specifies the size of the data to be logged, either the total size of the 82arguments required by the 83.Fa format 84string. 85For logging a fixed string with 86.Fn KTR_INFO , 87.Fa datasize 88is 0. 89The 90.Fa maskbit 91is a bit number that determines which of the corresponding 92.Va debug.ktr.*_enable 93sysctl's bits will enable logging of this event. 94.Pp 95Kernel events are logged via the 96.Fn KTR_LOG 97macro. 98The 99.Fa info 100parameter is an identifier of the format 101.Fa master Ns _ Ns Fa name . 102.Fn KTR_LOG 103accepts zero or more additional 104.Fa arg 105arguments as required by the 106.Fa format 107string passed to the associated 108.Fn KTR_INFO 109call. 110.Pp 111The 112.Va ktr_entries 113variable contains the number of entries in the 114.Va ktr_buf 115array. 116These variables are mostly useful for post-mortem crash dump tools to locate 117the base of the circular trace buffer and its length. 118.Pp 119The 120.Va ktr_verbose 121variable stores the verbose flag that controls whether events are logged to 122the console in addition to the event buffer. 123.Sh EXAMPLES 124This example demonstrates a simple usage of the KTR facility: 125.Pp 126.Bd -literal -compact 127#include <sys/ktr.h> 128 129\&... 130 131#if !defined(KTR_FOO) 132#define KTR_FOO KTR_ALL 133#endif 134KTR_INFO_MASTER(foo); 135KTR_INFO(KTR_FOO, foo, func1, 0, "func1()", 0); 136KTR_INFO(KTR_FOO, foo, func2, 1, "func2(%d)", sizeof(int)); 137 138\&... 139 140void 141func1(void) 142{ 143 KTR_LOG(foo_func1); 144 ... 145} 146 147void 148func2(int arg) 149{ 150 KTR_LOG(foo_func2, arg); 151 ... 152} 153.Ed 154.Sh SEE ALSO 155.Xr gdb 1 , 156.Xr ddb 4 , 157.Xr ktr 4 , 158.Xr ktrdump 8 , 159.Xr kprintf 9 160.Sh HISTORY 161The 162.Nm ktr 163kernel tracing facility first appeared in 164.Bsx 3.0 165and was imported into 166.Fx 5.0 167and 168.Dx 1.1 . 169It was completely rewritten by Matthew Dillon in 170.Dx 1.3 . 171