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32 .\" @(#)kdump.1 8.1 (Berkeley) 6/6/93
40 .Nd display kernel trace data
51 command displays the kernel trace files produced with
53 in human readable format.
56 in the current directory is displayed.
58 The options are as follows:
61 Display all numbers in decimal.
63 Display elapsed timestamps (time since beginning of trace).
65 Display the specified file instead of
68 Loop reading the trace file, once the end-of-file is reached, waiting for
76 Suppress ad hoc translations.
79 tries to decode many system calls into a more human readable format.
82 values are replaced with the macro name and
84 values are replaced with the
87 Suppressing this feature yields a more consistent output format and is
88 easily amenable to further processing.
90 Display only trace events that correspond to the process
92 This may be useful when there are multiple processes recorded in the
95 Display relative timestamps (time since previous entry).
97 Display absolute timestamps for each entry (seconds since epoch).
107 is line oriented with several fields.
108 The example below shows a section of a kdump generated by the following
110 .Bd -literal -offset indent
111 ?> ktrace echo "ktrace"
115 85045 echo CALL writev(0x1,0x804b030,0x2)
116 85045 echo GIO fd 1 wrote 7 bytes
119 85045 echo RET writev 7
122 The first field is the PID of the process being traced.
123 The second field is the name of the program being traced.
124 The third field is the operation that the kernel performed
125 on behalf of the process.
127 In the first line above, the kernel executes the
129 system call on behalf of the process so this is a
132 The fourth field shows the system call that was executed,
133 including its arguments.
136 system call takes a file descriptor, in this case 1, or standard
137 output, then a pointer to the iovector to write, and the number of
138 iovectors that are to be written.
139 In the second line we see the operation was
141 for general I/O, and that file descriptor 1 had
142 seven bytes written to it.
143 This is followed by the seven bytes that were written, the string
145 with a carriage return and line feed.
148 operation, showing a return from the kernel, what system call we are
149 returning from, and the return value that the process received.
150 Seven bytes were written by the
152 system call, so 7 is the return value.
154 The possible operations are:
155 .Bl -column -offset indent ".Li GENIO" ".No data from user process"
156 .It Sy Name Ta Sy Operation Ta Sy Fourth field
157 .It Li CALL Ta enter syscall Ta syscall name and arguments
158 .It Li RET Ta return from syscall Ta syscall name and return value
159 .It Li NAMI Ta file name lookup Ta path to file
160 .It Li GENIO Ta general I/O Ta fd, read/write, number of bytes
161 .It Li SIG Ta signal Ta signal name, handler, mask, code
162 .It Li CSW Ta context switch Ta stop/resume user/kernel
163 .It Li USER Ta data from user process Ta the data