183 lines
5.9 KiB
Groff
183 lines
5.9 KiB
Groff
.\" Copyright (c) 1990, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)kdump.1 8.1 (Berkeley) 6/6/93
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.\" $FreeBSD$
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.\"
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.Dd February 23, 2008
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.Dt KDUMP 1
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.Os
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.Sh NAME
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.Nm kdump
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.Nd display kernel trace data
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.Sh SYNOPSIS
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.Nm
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.Op Fl dEnlHRsT
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.Op Fl f Ar trfile
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.Op Fl m Ar maxdata
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.Op Fl p Ar pid
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.Op Fl t Ar trstr
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.Sh DESCRIPTION
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The
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.Nm
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command displays the kernel trace files produced with
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.Xr ktrace 1
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in human readable format.
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By default, the file
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.Pa ktrace.out
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in the current directory is displayed.
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.Pp
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The options are as follows:
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.Bl -tag -width Fl
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.It Fl d
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Display all numbers in decimal.
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.It Fl E
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Display elapsed timestamps (time since beginning of trace).
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.It Fl f Ar trfile
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Display the specified file instead of
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.Pa ktrace.out .
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.It Fl H
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List the thread ID (tid) of the thread with each trace record, if available.
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If no thread ID is available, 0 will be printed.
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.It Fl l
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Loop reading the trace file, once the end-of-file is reached, waiting for
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more data.
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.It Fl m Ar maxdata
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Display at most
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.Ar maxdata
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bytes when decoding
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.Tn I/O .
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.It Fl n
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Suppress ad hoc translations.
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Normally
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.Nm
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tries to decode many system calls into a more human readable format.
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For example,
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.Xr ioctl 2
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values are replaced with the macro name and
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.Va errno
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values are replaced with the
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.Xr strerror 3
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string.
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Suppressing this feature yields a more consistent output format and is
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easily amenable to further processing.
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.It Fl p Ar pid
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Display only trace events that correspond to the process
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.Ar pid .
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This may be useful when there are multiple processes recorded in the
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same trace file.
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.It Fl R
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Display relative timestamps (time since previous entry).
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.It Fl r
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When decoding STRU records, display structure members such as UIDs,
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GIDs, dates etc. symbolically instead of numerically.
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.It Fl s
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Suppress display of I/O data.
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.It Fl T
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Display absolute timestamps for each entry (seconds since epoch).
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.It Fl t Ar trstr
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See the
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.Fl t
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option of
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.Xr ktrace 1 .
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.El
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.Pp
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The output format of
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.Nm
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is line oriented with several fields.
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The example below shows a section of a kdump generated by the following
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commands:
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.Bd -literal -offset indent
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?> ktrace echo "ktrace"
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?> kdump
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85045 echo CALL writev(0x1,0x804b030,0x2)
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85045 echo GIO fd 1 wrote 7 bytes
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"ktrace
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"
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85045 echo RET writev 7
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.Ed
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.Pp
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The first field is the PID of the process being traced.
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The second field is the name of the program being traced.
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The third field is the operation that the kernel performed
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on behalf of the process.
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If thread IDs are being printed, then an additional thread ID column will be
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added to the output between the PID field and program name field.
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.Pp
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In the first line above, the kernel executes the
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.Xr writev 2
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system call on behalf of the process so this is a
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.Li CALL
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operation.
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The fourth field shows the system call that was executed,
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including its arguments.
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The
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.Xr writev 2
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system call takes a file descriptor, in this case 1, or standard
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output, then a pointer to the iovector to write, and the number of
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iovectors that are to be written.
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In the second line we see the operation was
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.Li GIO ,
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for general I/O, and that file descriptor 1 had
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seven bytes written to it.
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This is followed by the seven bytes that were written, the string
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.Qq Li ktrace
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with a carriage return and line feed.
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The last line is the
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.Li RET
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operation, showing a return from the kernel, what system call we are
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returning from, and the return value that the process received.
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Seven bytes were written by the
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.Xr writev 2
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system call, so 7 is the return value.
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.Pp
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The possible operations are:
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.Bl -column -offset indent ".Li GENIO" ".No data from user process"
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.It Sy Name Ta Sy Operation Ta Sy Fourth field
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.It Li CALL Ta enter syscall Ta syscall name and arguments
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.It Li RET Ta return from syscall Ta syscall name and return value
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.It Li NAMI Ta file name lookup Ta path to file
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.It Li GENIO Ta general I/O Ta fd, read/write, number of bytes
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.It Li SIG Ta signal Ta signal name, handler, mask, code
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.It Li CSW Ta context switch Ta stop/resume user/kernel
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.It Li USER Ta data from user process Ta the data
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.It Li STRU Ta various syscalls Ta structure
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.El
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.Sh SEE ALSO
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.Xr ktrace 1
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.Sh HISTORY
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The
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.Nm
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command appeared in
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.Bx 4.4 .
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