xref: /freebsd/usr.bin/kdump/kdump.1 (revision 8d20be1e22095c27faf8fe8b2f0d089739cc742e)
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28.\"	@(#)kdump.1	8.1 (Berkeley) 6/6/93
29.\" $FreeBSD$
30.\"
31.Dd June 4, 2012
32.Dt KDUMP 1
33.Os
34.Sh NAME
35.Nm kdump
36.Nd display kernel trace data
37.Sh SYNOPSIS
38.Nm
39.Op Fl dEnlHRsTA
40.Op Fl f Ar trfile
41.Op Fl m Ar maxdata
42.Op Fl p Ar pid
43.Op Fl t Ar trstr
44.Sh DESCRIPTION
45The
46.Nm
47command displays the kernel trace files produced with
48.Xr ktrace 1
49in human readable format.
50By default, the file
51.Pa ktrace.out
52in the current directory is displayed.
53.Pp
54The options are as follows:
55.Bl -tag -width Fl
56.It Fl d
57Display all numbers in decimal.
58.It Fl E
59Display elapsed timestamps (time since beginning of trace).
60.It Fl f Ar trfile
61Display the specified file instead of
62.Pa ktrace.out .
63.It Fl H
64List the thread ID (tid) of the thread with each trace record, if available.
65If no thread ID is available, 0 will be printed.
66.It Fl l
67Loop reading the trace file, once the end-of-file is reached, waiting for
68more data.
69.It Fl m Ar maxdata
70Display at most
71.Ar maxdata
72bytes when decoding
73.Tn I/O .
74.It Fl n
75Suppress ad hoc translations.
76Normally
77.Nm
78tries to decode many system calls into a more human readable format.
79For example,
80.Xr ioctl 2
81values are replaced with the macro name and
82.Va errno
83values are replaced with the
84.Xr strerror 3
85string.
86Suppressing this feature yields a more consistent output format and is
87easily amenable to further processing.
88.It Fl p Ar pid
89Display only trace events that correspond to the process or thread
90.Ar pid .
91This may be useful when there are multiple processes or threads recorded in the
92same trace file.
93.It Fl R
94Display relative timestamps (time since previous entry).
95.It Fl r
96When decoding STRU records, display structure members such as UIDs,
97GIDs, dates etc. symbolically instead of numerically.
98.It Fl s
99Suppress display of I/O data.
100.It Fl T
101Display absolute timestamps for each entry (seconds since epoch).
102.It Fl A
103Display description of the ABI of traced process.
104.It Fl t Ar trstr
105See the
106.Fl t
107option of
108.Xr ktrace 1 .
109.El
110.Pp
111The output format of
112.Nm
113is line oriented with several fields.
114The example below shows a section of a kdump generated by the following
115commands:
116.Bd -literal -offset indent
117?> ktrace echo "ktrace"
118
119?> kdump
120
121 85045 echo     CALL  writev(0x1,0x804b030,0x2)
122 85045 echo     GIO   fd 1 wrote 7 bytes
123       "ktrace
124       "
125 85045 echo     RET   writev 7
126.Ed
127.Pp
128The first field is the PID of the process being traced.
129The second field is the name of the program being traced.
130The third field is the operation that the kernel performed
131on behalf of the process.
132If thread IDs are being printed, then an additional thread ID column will be
133added to the output between the PID field and program name field.
134.Pp
135In the first line above, the kernel executes the
136.Xr writev 2
137system call on behalf of the process so this is a
138.Li CALL
139operation.
140The fourth field shows the system call that was executed,
141including its arguments.
142The
143.Xr writev 2
144system call takes a file descriptor, in this case 1, or standard
145output, then a pointer to the iovector to write, and the number of
146iovectors that are to be written.
147In the second line we see the operation was
148.Li GIO ,
149for general I/O, and that file descriptor 1 had
150seven bytes written to it.
151This is followed by the seven bytes that were written, the string
152.Qq Li ktrace
153with a carriage return and line feed.
154The last line is the
155.Li RET
156operation, showing a return from the kernel, what system call we are
157returning from, and the return value that the process received.
158Seven bytes were written by the
159.Xr writev 2
160system call, so 7 is the return value.
161.Pp
162The possible operations are:
163.Bl -column -offset indent ".Li CALL" ".No data from user process"
164.It Sy Name Ta Sy Operation Ta Sy Fourth field
165.It Li CALL Ta enter syscall Ta syscall name and arguments
166.It Li RET Ta return from syscall Ta syscall name and return value
167.It Li NAMI Ta file name lookup Ta path to file
168.It Li GIO Ta general I/O Ta fd, read/write, number of bytes
169.It Li PSIG Ta signal Ta signal name, handler, mask, code
170.It Li CSW Ta context switch Ta stop/resume user/kernel wmesg
171.It Li USER Ta data from user process Ta the data
172.It Li STRU Ta various syscalls Ta structure
173.It Li SCTL Ta Xr sysctl 3 requests Ta MIB name
174.It Li PFLT Ta enter page fault Ta fault address and type
175.It Li PRET Ta return from page fault Ta fault result
176.El
177.Sh SEE ALSO
178.Xr ktrace 1
179.Sh HISTORY
180The
181.Nm
182command appeared in
183.Bx 4.4 .
184