1MAKEDUMPFILE(8) Linux System Administrator's Manual MAKEDUMPFILE(8)
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6 makedumpfile - make a small dumpfile of kdump
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9 makedumpfile [OPTION] [-x VMLINUX|-i VMCOREINFO] VMCORE DUMPFILE
10 makedumpfile -F [OPTION] [-x VMLINUX|-i VMCOREINFO] VMCORE
11 makedumpfile -R DUMPFILE
12 makedumpfile --split [OPTION] [-x VMLINUX|-i VMCOREINFO] VMCORE DUMP‐
13 FILE1 DUMPFILE2 [DUMPFILE3 ..]
14 makedumpfile --reassemble DUMPFILE1 DUMPFILE2 [DUMPFILE3 ..] DUMPFILE
15 makedumpfile -g VMCOREINFO -x VMLINUX
16 makedumpfile -E [--xen-syms XEN-SYMS|--xen-vmcoreinfo VMCOREINFO]
17 VMCORE DUMPFILE
18 makedumpfile --dump-dmesg [-x VMLINUX|-i VMCOREINFO] VMCORE LOGFILE
19 makedumpfile -h
20 makedumpfile -v
21
23 With kdump, the memory image of the first kernel (called "panicked ker‐
24 nel") can be taken as /proc/vmcore while the second kernel (called
25 "kdump kernel" or "capture kernel") is running. This document repre‐
26 sents /proc/vmcore as VMCORE. makedumpfile makes a small DUMPFILE by
27 compressing dump data or by excluding unnecessary pages for analysis,
28 or both. makedumpfile needs the first kernel's debug information, so
29 that it can distinguish unnecessary pages by analyzing how the first
30 kernel uses the memory. The information can be taken from VMLINUX or
31 VMCOREINFO.
32 makedumpfile can exclude the following types of pages while copying
34 VMCORE to DUMPFILE, and a user can choose which type of pages will be
35 excluded.
36 - Pages filled with zero
37 - Cache pages
38 - User process data pages
39 - Free pages
40 makedumpfile provides two DUMPFILE formats (the ELF format and the
42 kdump-compressed format). By default, makedumpfile makes a DUMPFILE in
43 the kdump-compressed format. The kdump-compressed format is readable
44 only with the crash utility, and it can be smaller than the ELF format
45 because of the compression support. The ELF format is readable with GDB
46 and the crash utility. If a user wants to use GDB, DUMPFILE format has
47 to be explicitly specified to be the ELF format.
48 To analyze the first kernel's memory usage, makedumpfile can refer to
50 VMCOREINFO instead of VMLINUX. VMCOREINFO contains the first kernel's
51 information (structure size, field offset, etc.), and VMCOREINFO is
52 small enough to be included into the second kernel's initrd.
53 If the second kernel is running on its initrd without mounting a root
54 file system, makedumpfile cannot refer to VMLINUX because the second
55 kernel's initrd cannot include a large file like VMLINUX. To solve the
56 problem, makedumpfile makes VMCOREINFO beforehand, and it refers to
57 VMCOREINFO instead of VMLINUX while the second kernel is running.
58 VMCORE has contained VMCOREINFO since linux-2.6.24, and a user does not
59 need to specify neither -x nor -i option.
60 If the second kernel is running on its initrd without mounting any file
62 system, a user needs to transport the dump data to a remote host. To
63 transport the dump data by SSH, makedumpfile outputs the dump data in
64 the intermediate format (the flattened format) to the standard output.
65 By piping the output data to SSH, a user can transport the dump data to
66 a remote host. Note that analysis tools cannot read the flattened for‐
67 mat directly, so on a remote host the received data in the flattened
68 format needs to be rearranged to a readable DUMPFILE format by make‐
69 dumpfile (or makedumpfile-R.pl).
70 makedumpfile can read a DUMPFILE in the kdump-compressed format instead
72 of VMCORE and re-filter it. This feature is useful in situation that
73 users need to reduce the file size of DUMPFILE for sending it somewhere
74 by ftp/scp/etc. (If all of the page types, which are specified by a new
75 dump_level, are excluded from an original DUMPFILE already, a new DUMP‐
76 FILE is the same as an original DUMPFILE.)
77 For example, makedumpfile can create a DUMPFILE of dump_level 31 from
78 the one of dump_level 3 like the following:
79 Example:
80 # makedumpfile -c -d 3 /proc/vmcore dumpfile.1
81 # makedumpfile -c -d 31 dumpfile.1 dumpfile.2
82
85 -c Compress dump data by each page.
86 A user cannot specify this option with -E option, because the
87 ELF format does not support compressed data.
88 Example:
89 # makedumpfile -c -d 31 -x vmlinux /proc/vmcore dumpfile
90 -d dump_level
93 Specify the type of unnecessary page for analysis.
94 Pages of the specified type are not copied to DUMPFILE. The page
95 type marked in the following table is excluded. A user can spec‐
96 ify multiple page types by setting the sum of each page type for
97 dump_level. The maximum of dump_level is 31. Note that a
98 dump_level for Xen dump filtering is 0 or 1 on a machine other
99 than x86_64 (On an x86_64 machine, it is possible to specify 2
100 or bigger as a dump_level).
101 If specifying multiple dump_levels with the delimiter ',', make‐
102 dumpfile retries to create a DUMPFILE by other dump_level when
103 "No space on device" error happens. For example, if dump_level
104 is "11,31" and makedumpfile fails by dump_level 11, makedumpfile
105 retries it by dump_level 31.
106 Example:
107 # makedumpfile -d 11 -x vmlinux /proc/vmcore dumpfile
108 # makedumpfile -d 11,31 -x vmlinux /proc/vmcore dumpfile
109 dump | zero | cache|cache | user | free
111 level | page | page |private| data | page
112 -------+------+------+-------+------+------
113 0 | | | | |
114 1 | X | | | |
115 2 | | X | | |
116 3 | X | X | | |
117 4 | | X | X | |
118 5 | X | X | X | |
119 6 | | X | X | |
120 7 | X | X | X | |
121 8 | | | | X |
122 9 | X | | | X |
123 10 | | X | | X |
124 11 | X | X | | X |
125 12 | | X | X | X |
126 13 | X | X | X | X |
127 14 | | X | X | X |
128 15 | X | X | X | X |
129 16 | | | | | X
130 17 | X | | | | X
131 18 | | X | | | X
132 19 | X | X | | | X
133 20 | | X | X | | X
134 21 | X | X | X | | X
135 22 | | X | X | | X
136 23 | X | X | X | | X
137 24 | | | | X | X
138 25 | X | | | X | X
139 26 | | X | | X | X
140 27 | X | X | | X | X
141 28 | | X | X | X | X
142 29 | X | X | X | X | X
143 30 | | X | X | X | X
144 31 | X | X | X | X | X
145 -E Create DUMPFILE in the ELF format.
149 This option cannot be specified with -c option, because the ELF
150 format does not support compressed data.
151 Example:
152 # makedumpfile -E -d 31 -x vmlinux /proc/vmcore dumpfile
153 -f Force existing DUMPFILE to be overwritten.
156 Example:
157 # makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile
158 This command overwrites DUMPFILE even if it already exists.
159 -x VMLINUX
162 Specify the first kernel's VMLINUX with debug information to
163 analyze the first kernel's memory usage.
164 This option is necessary if VMCORE does not contain VMCOREINFO,
165 [-i VMCOREINFO] is not specified, and dump_level is 2 or more.
166 The page size of the first kernel and the second kernel should
167 match.
168 Example:
169 # makedumpfile -d 31 -x vmlinux /proc/vmcore dumpfile
170 -i VMCOREINFO
173 Specify VMCOREINFO instead of VMLINUX for analyzing the first
174 kernel's memory usage.
175 VMCOREINFO should be made beforehand by makedumpfile with -g
176 option, and it contains the first kernel's information.
177 This option is necessary if VMCORE does not contain VMCOREINFO,
178 [-x VMLINUX] is not specified, and dump_level is 2 or more.
179 Example:
180 # makedumpfile -d 31 -i vmcoreinfo /proc/vmcore dumpfile
181 -g VMCOREINFO
184 Generate VMCOREINFO from the first kernel's VMLINUX with debug
185 information.
186 VMCOREINFO must be generated on the system that is running the
187 first kernel. With -i option, a user can specify VMCOREINFO gen‐
188 erated on the other system that is running the same first ker‐
189 nel. [-x VMLINUX] must be specified.
190 Example:
191 # makedumpfile -g vmcoreinfo -x vmlinux
192 -F Output the dump data in the flattened format to the standard
195 output for transporting the dump data by SSH.
196 Analysis tools cannot read the flattened format directly. For
197 analysis, the dump data in the flattened format should be rear‐
198 ranged to a normal DUMPFILE (readable with analysis tools) by -R
199 option. By which option is specified with -F option, the format
200 of the rearranged DUMPFILE is fixed. In other words, it is
201 impossible to specify the DUMPFILE format when the dump data is
202 rearranged with -R option. If specifying -E option with -F
203 option, the format of the rearranged DUMPFILE is the ELF format.
204 Otherwise, it is the kdump-compressed format. All the messages
205 are output to standard error output by -F option because stan‐
206 dard output is used for the dump data.
207 Example:
208 # makedumpfile -F -c -d 31 -x vmlinux /proc/vmcore \
209 | ssh user@host "cat > dumpfile.tmp"
210 # makedumpfile -F -c -d 31 -x vmlinux /proc/vmcore \
211 | ssh user@host "makedumpfile -R dumpfile"
212 # makedumpfile -F -E -d 31 -i vmcoreinfo /proc/vmcore \
213 | ssh user@host "makedumpfile -R dumpfile"
214 # makedumpfile -F -E --xen-vmcoreinfo VMCOREINFO /proc/vmcore \
215 | ssh user@host "makedumpfile -R dumpfile"
216 -R Rearrange the dump data in the flattened format from the stan‐
219 dard input to a normal DUMPFILE (readable with analysis tools).
220 Example:
221 # makedumpfile -R dumpfile < dumpfile.tmp
222 # makedumpfile -F -d 31 -x vmlinux /proc/vmcore \
223 | ssh user@host "makedumpfile -R dumpfile"
224 Instead of using -R option, a perl script "makedumpfile-R.pl"
226 rearranges the dump data in the flattened format to a normal
227 DUMPFILE, too. The perl script does not depend on architecture,
228 and most systems have perl command. Even if a remote host does
229 not have makedumpfile, it is possible to rearrange the dump data
230 in the flattened format to a readable DUMPFILE on a remote host
231 by running this script.
232 Example:
233 # makedumpfile -F -d 31 -x vmlinux /proc/vmcore \
234 | ssh user@host "makedumpfile-R.pl dumpfile"
235 --split
238 Split the dump data to multiple DUMPFILEs in parallel. If speci‐
239 fying DUMPFILEs on different storage devices, a device can share
240 I/O load with other devices and it reduces time for saving the
241 dump data. The file size of each DUMPFILE is smaller than the
242 system memory size which is divided by the number of DUMPFILEs.
243 This feature supports only the kdump-compressed format.
244 Example:
245 # makedumpfile --split -d 31 -x vmlinux /proc/vmcore dumpfile1
246 dumpfile2
247 --reassemble
250 Reassemble multiple DUMPFILEs, which are created by --split
251 option, into one DUMPFILE. dumpfile1 and dumpfile2 are reassem‐
252 bled into dumpfile on the following example.
253 Example:
254 # makedumpfile --reassemble dumpfile1 dumpfile2 dumpfile
255 --xen-syms XEN-SYMS
258 Specify the XEN-SYMS with debug information to analyze the xen's
259 memory usage. This option extracts the part of xen and
260 domain-0. -E option must be specified with this option.
261 Example:
262 # makedumpfile -E --xen-syms xen-syms /proc/vmcore dumpfile
263 --xen-vmcoreinfo VMCOREINFO
266 Specify VMCOREINFO instead of XEN-SYMS for analyzing the xen's
267 memory usage.
268 VMCOREINFO should be made beforehand by makedumpfile with -g
269 option, and it contains the xen's information. -E option must
270 be specified with this option.
271 Example:
272 # makedumpfile -E --xen-vmcoreinfo VMCOREINFO /proc/vmcore dump‐
273 file
274 -X Exclude all the user domain pages from Xen kdump's VMCORE, and
277 extracts the part of xen and domain-0. If VMCORE contains VMCOR‐
278 EINFO for Xen, it is not necessary to specify --xen-syms and
279 --xen-vmcoreinfo. -E option must be specified with this option.
280 Example:
281 # makedumpfile -E -X /proc/vmcore dumpfile
282 --xen_phys_start xen_phys_start_address
285 This option is only for x86_64. Specify the
286 xen_phys_start_address, if the xen code/data is relocatable and
287 VMCORE does not contain xen_phys_start_address in the CRASHINFO.
288 xen_phys_start_address can be taken from the line of "Hypervisor
289 code and data" in /proc/iomem. For example, specify 0xcee00000
290 as xen_phys_start_address if /proc/iomem is the following:
291 -------------------------------------------------------
292 # cat /proc/iomem
293 ...
294 cee00000-cfd99999 : Hypervisor code and data
295 ...
296 -------------------------------------------------------
297 Example:
299 # makedumpfile -E -X --xen_phys_start 0xcee00000 /proc/vmcore
300 dumpfile
301 --message-level message_level
304 Specify the message types.
305 Users can restrict outputs printed by specifying message_level
306 with this option. The message type marked with an X in the fol‐
307 lowing table is printed. For example, according to the table,
308 specifying 7 as message_level means progress indicator, common
309 message, and error message are printed, and this is a default
310 value. Note that the maximum value of message_level is 31.
311 message | progress | common | error | debug | report
313 level | indicator| message | message | message | message
314 ---------+----------+---------+---------+---------+---------
315 0 | | | | |
316 1 | X | | | |
317 2 | | X | | |
318 3 | X | X | | |
319 4 | | | X | |
320 5 | X | | X | |
321 6 | | X | X | |
322 * 7 | X | X | X | |
323 8 | | | | X |
324 9 | X | | | X |
325 10 | | X | | X |
326 11 | X | X | | X |
327 12 | | | X | X |
328 13 | X | | X | X |
329 14 | | X | X | X |
330 15 | X | X | X | X |
331 16 | | | | | X
332 17 | X | | | | X
333 18 | | X | | | X
334 19 | X | X | | | X
335 20 | | | X | | X
336 21 | X | | X | | X
337 22 | | X | X | | X
338 23 | X | X | X | | X
339 24 | | | | X | X
340 25 | X | | | X | X
341 26 | | X | | X | X
342 27 | X | X | | X | X
343 28 | | | X | X | X
344 29 | X | | X | X | X
345 30 | | X | X | X | X
346 31 | X | X | X | X | X
347 --vtop virtual_address
350 This option is useful, when user debugs the translation problem
351 of virtual address. If specifing virtual_address, its physical
352 address is printed. It makes debugging easy by comparing the
353 output of this option with the one of "vtop" subcommand of the
354 crash utility. "--vtop" option only prints the translation out‐
355 put, and it does not affect the dumpfile creation.
356 --dump-dmesg
359 This option overrides the normal behavior of makedumpfile.
360 Instead of compressing and filtering a VMCORE to make it
361 smaller, it simply extracts the dmesg log from a VMCORE and
362 writes it to the specified LOGFILE. If a VMCORE does not contain
363 VMCOREINFO for dmesg, it is necessary to specfiy [-x VMLINUX] or
364 [-i VMCOREINFO].
365 Example:
367 # makedumpfile --dump-dmesg /proc/vmcore dmesgfile
368 # makedumpfile --dump-dmesg -x vmlinux /proc/vmcore dmesgfile
369 -D Print debugging message.
372 -b <order>
375 cache 2^order pages in ram when generating vmcore info before
376 writing to output
377 -h Show help message.
380 -v Show the version of makedumpfile.
383
386 makedumpfile exits with the following value.
387 0 : makedumpfile succeeded.
389 1 : makedumpfile failed without the following reasons.
391 2 : makedumpfile failed due to the different version between VMLINUX
393 and VMCORE.
394 3 : makedumpfile failed due to the analysis error of the memory.
396
399 Written by Masaki Tachibana, and Ken'ichi Ohmichi.
400
403 crash(8), gdb(1), kexec(8)
404makedumpfile v1.3.5 11 November 2009 MAKEDUMPFILE(8)