1 .\" Copyright (c) 2001 John H. Baldwin <jhb@FreeBSD.org>
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25 .\" $FreeBSD: src/share/man/man9/ktr.9,v 1.8 2005/03/08 01:37:36 hmp Exp $
26 .\" $DragonFly: src/share/man/man9/ktr.9,v 1.11 2008/01/08 17:45:43 swildner Exp $
35 .Nd kernel tracing facility
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 "compile" "master" "name" "maskbit" "format" "datasize"
43 .Fn KTR_LOG "info" "arg ..."
47 facility provides a circular buffer of events that can be logged in a
50 These events can then be dumped with
57 declares a new master variable
58 .Dv ktr Ns _ Ns Fa master Ns _ Ns Dv enable
59 that is used to turn on and off event logging.
63 macro registers a new event
65 that will be controlled by the
68 Code for logging this event will be compiled in when
75 style format string used to build the text of the event log message while
77 specifies the size of the data to be logged, either the total size of the
78 arguments required by the
80 string or the size of the data pointer
82 For logging a fixed string with
88 is currently unused and can be set to 0.
90 Kernel events are logged via the
95 parameter is an identifier of the format
96 .Fa master Ns _ Ns Fa name .
98 accepts zero or more additional
100 arguments as required by the
102 string passed to the associated
108 variable contains the number of entries in the
111 These variables are mostly useful for post-mortem crash dump tools to locate
112 the base of the circular trace buffer and its length.
116 variable stores the verbose flag that controls whether events are logged to
117 the console in addition to the event buffer.
119 This example demonstrates a simple usage of the KTR facility:
121 .Bd -literal -compact
126 #if !defined(KTR_FOO)
127 #define KTR_FOO KTR_ALL
129 KTR_INFO_MASTER(foo);
130 KTR_INFO(KTR_FOO, foo, func1, 0, "func1()", 0);
131 KTR_INFO(KTR_FOO, foo, func2, 1, "func2(%d)", sizeof(int));
145 KTR_LOG(foo_func2, arg);
158 kernel tracing facility first appeared in
160 and was imported into
164 It was completely rewritten by Matthew Dillon in