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28 .\" @(#)kdump.1 8.1 (Berkeley) 6/6/93
36 .Nd display kernel trace data
47 command displays the kernel trace files produced with
49 in human readable format.
52 in the current directory is displayed.
54 The options are as follows:
57 Display all numbers in decimal.
59 Display elapsed timestamps (time since beginning of trace).
61 Display the specified file instead of
64 List the thread ID (tid) of the thread with each trace record, if available.
65 If no thread ID is available, 0 will be printed.
67 Loop reading the trace file, once the end-of-file is reached, waiting for
75 Suppress ad hoc translations.
78 tries to decode many system calls into a more human readable format.
81 values are replaced with the macro name and
83 values are replaced with the
86 Suppressing this feature yields a more consistent output format and is
87 easily amenable to further processing.
89 Display only trace events that correspond to the process or thread
91 This may be useful when there are multiple processes or threads recorded in the
94 Display relative timestamps (time since previous entry).
96 When decoding STRU records, display structure members such as UIDs,
97 GIDs, dates etc. symbolically instead of numerically.
99 Display system call numbers.
101 Suppress display of I/O data.
103 Display absolute timestamps for each entry (seconds since epoch).
105 Display description of the ABI of traced process.
115 is line oriented with several fields.
116 The example below shows a section of a kdump generated by the following
118 .Bd -literal -offset indent
119 ?> ktrace echo "ktrace"
123 85045 echo CALL writev(0x1,0x804b030,0x2)
124 85045 echo GIO fd 1 wrote 7 bytes
127 85045 echo RET writev 7
130 The first field is the PID of the process being traced.
131 The second field is the name of the program being traced.
132 The third field is the operation that the kernel performed
133 on behalf of the process.
134 If thread IDs are being printed, then an additional thread ID column will be
135 added to the output between the PID field and program name field.
137 In the first line above, the kernel executes the
139 system call on behalf of the process so this is a
142 The fourth field shows the system call that was executed,
143 including its arguments.
146 system call takes a file descriptor, in this case 1, or standard
147 output, then a pointer to the iovector to write, and the number of
148 iovectors that are to be written.
149 In the second line we see the operation was
151 for general I/O, and that file descriptor 1 had
152 seven bytes written to it.
153 This is followed by the seven bytes that were written, the string
155 with a carriage return and line feed.
158 operation, showing a return from the kernel, what system call we are
159 returning from, and the return value that the process received.
160 Seven bytes were written by the
162 system call, so 7 is the return value.
164 The possible operations are:
165 .Bl -column -offset indent ".Li CALL" ".No data from user process"
166 .It Sy Name Ta Sy Operation Ta Sy Fourth field
167 .It Li CALL Ta enter syscall Ta syscall name and arguments
168 .It Li RET Ta return from syscall Ta syscall name and return value
169 .It Li NAMI Ta file name lookup Ta path to file
170 .It Li GIO Ta general I/O Ta fd, read/write, number of bytes
171 .It Li PSIG Ta signal Ta signal name, handler, mask, code
172 .It Li CSW Ta context switch Ta stop/resume user/kernel wmesg
173 .It Li USER Ta data from user process Ta the data
174 .It Li STRU Ta various syscalls Ta structure
175 .It Li SCTL Ta Xr sysctl 3 requests Ta MIB name
176 .It Li PFLT Ta enter page fault Ta fault address and type
177 .It Li PRET Ta return from page fault Ta fault result