freebsd/usr.bin/kdump/kdump.1

.\" Copyright (c) 1990, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"	@(#)kdump.1	8.1 (Berkeley) 6/6/93
.\" $FreeBSD$
.\"
.Dd January 28, 2005
.Dt KDUMP 1
.Os
.Sh NAME
.Nm kdump
.Nd display kernel trace data
.Sh SYNOPSIS
.Nm
.Op Fl dEnlRT
.Op Fl f Ar trfile
.Op Fl m Ar maxdata
.Op Fl p Ar pid
.Op Fl t Op cnisuw
.Sh DESCRIPTION
The
.Nm
command displays the kernel trace files produced with
.Xr ktrace 1
in human readable format.
By default, the file
.Pa ktrace.out
in the current directory is displayed.
.Pp
The options are as follows:
.Bl -tag -width Fl
.It Fl d
Display all numbers in decimal.
.It Fl E
Display elapsed timestamps (time since beginning of trace).
.It Fl f Ar trfile
Display the specified file instead of
.Pa ktrace.out .
.It Fl l
Loop reading the trace file, once the end-of-file is reached, waiting for
more data.
.It Fl m Ar maxdata
Display at most
.Ar maxdata
bytes when decoding
.Tn I/O .
.It Fl n
Suppress ad hoc translations.
Normally
.Nm
tries to decode many system calls into a more human readable format.
For example,
.Xr ioctl 2
values are replaced with the macro name and
.Va errno
values are replaced with the
.Xr strerror 3
string.
Suppressing this feature yields a more consistent output format and is
easily amenable to further processing.
.It Fl p Ar pid
Display only trace events that correspond to the process
.Ar pid .
This may be useful when there are multiple processes recorded in the
same trace file.
.It Fl R
Display relative timestamps (time since previous entry).
.It Fl T
Display absolute timestamps for each entry (seconds since epoch).
.It Fl t Ar cnisuw
See the
.Fl t
option of
.Xr ktrace 1 .
.El
.Pp
The output format of
.Nm
is line oriented with several fields.
The example below shows a section of a kdump generated by the following
commands:
.Bd -literal -offset indent
?> ktrace echo "ktrace"

?> kdump

 85045 echo     CALL  writev(0x1,0x804b030,0x2)
 85045 echo     GIO   fd 1 wrote 7 bytes
       "ktrace
       "
 85045 echo     RET   writev 7
.Ed
.Pp
The first field is the PID of the process being traced.
The second field is the name of the program being traced.
The third field is the operation that the kernel performed
on behalf of the process.
.Pp
In the first line above, the kernel executes the
.Xr writev 2
system call on behalf of the process so this is a
.Li CALL
operation.
The fourth field shows the system call that was executed,
including its arguments.
The
.Xr writev 2
system call takes a file descriptor, in this case 1, or standard
output, then a pointer to the iovector to write, and the number of
iovectors that are to be written.
In the second line we see the operation was
.Li GIO ,
for general I/O, and that file descriptor 1 had
seven bytes written to it.
This is followed by the seven bytes that were written, the string
.Qq Li ktrace
with a carriage return and line feed.
The last line is the
.Li RET
operation, showing a return from the kernel, what system call we are
returning from, and the return value that the process received.
Seven bytes were written by the
.Xr writev 2
system call, so 7 is the return value.
.Pp
The possible operations are:
.Bl -column -offset indent ".Li GENIO" ".No data from user process"
.It Sy Name Ta Sy Operation Ta Sy Fourth field
.It Li CALL Ta enter syscall Ta syscall name and arguments
.It Li RET Ta return from syscall Ta syscall name and return value
.It Li NAMI Ta file name lookup Ta path to file
.It Li GENIO Ta general I/O Ta fd, read/write, number of bytes
.It Li SIG Ta signal Ta signal name, handler, mask, code
.It Li CSW Ta context switch Ta stop/resume user/kernel
.It Li USER Ta data from user process Ta the data
.El
.Sh SEE ALSO
.Xr ktrace 1
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.4 .