1MAKEDUMPFILE(8) Linux System Administrator's Manual MAKEDUMPFILE(8)
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6 makedumpfile - make a small dumpfile of kdump
7
9 makedumpfile [OPTION] [-x VMLINUX|-i VMCOREINFO] VMCORE DUMPFILE
10 makedumpfile -F [OPTION] [-x VMLINUX|-i VMCOREINFO] VMCORE
11 makedumpfile [OPTION] -x VMLINUX [--config FILTERCONFIGFILE] [--eppic
12 EPPICMACRO] VMCORE DUMPFILE
13 makedumpfile -R DUMPFILE
14 makedumpfile --split [OPTION] [-x VMLINUX|-i VMCOREINFO] VMCORE DUMP‐
15 FILE1 DUMPFILE2 [DUMPFILE3 ..]
16 makedumpfile --reassemble DUMPFILE1 DUMPFILE2 [DUMPFILE3 ..] DUMPFILE
17 makedumpfile -g VMCOREINFO -x VMLINUX
18 makedumpfile -E [--xen-syms XEN-SYMS|--xen-vmcoreinfo VMCOREINFO]
19 VMCORE DUMPFILE
20 makedumpfile --dump-dmesg [-x VMLINUX|-i VMCOREINFO] VMCORE LOGFILE
21 makedumpfile [OPTION] -x VMLINUX --diskset=VMCORE1 --diskset=VMCORE2
22 [--diskset=VMCORE3 ..] DUMPFILE
23 makedumpfile -h
24 makedumpfile -v
25
27 With kdump, the memory image of the first kernel (called "panicked ker‐
28 nel") can be taken as /proc/vmcore while the second kernel (called
29 "kdump kernel" or "capture kernel") is running. This document repre‐
30 sents /proc/vmcore as VMCORE. makedumpfile makes a small DUMPFILE by
31 compressing dump data or by excluding unnecessary pages for analysis,
32 or both. makedumpfile needs the first kernel's debug information, so
33 that it can distinguish unnecessary pages by analyzing how the first
34 kernel uses the memory. The information can be taken from VMLINUX or
35 VMCOREINFO.
36 makedumpfile can exclude the following types of pages while copying
38 VMCORE to DUMPFILE, and a user can choose which type of pages will be
39 excluded.
40 - Pages filled with zero
41 - Cache pages without private pages
42 - All cache pages with private pages
43 - User process data pages
44 - Free pages
45 makedumpfile provides two DUMPFILE formats (the ELF format and the
47 kdump-compressed format). By default, makedumpfile makes a DUMPFILE in
48 the kdump-compressed format. The kdump-compressed format is readable
49 only with the crash utility, and it can be smaller than the ELF format
50 because of the compression support. The ELF format is readable with GDB
51 and the crash utility. If a user wants to use GDB, DUMPFILE format has
52 to be explicitly specified to be the ELF format.
53 Apart from the exclusion of unnecessary pages mentioned above, make‐
55 dumpfile allows user to filter out targeted kernel data. The filter
56 config file can be used to specify kernel/module symbols and its mem‐
57 bers that need to be filtered out through the erase command syntax.
58 makedumpfile reads the filter config and builds the list of memory
59 addresses and its sizes after processing filter commands. The memory
60 locations that require to be filtered out are then poisoned with char‐
61 acter 'X' (58 in Hex). Refer to makedumpfile.conf(5) for file format.
62 Eppic macros can also be used to specify kernel symbols and its members
64 that need to be filtered. Eppic provides C semantics including language
65 constructs such as conditional statements, logical and arithmetic oper‐
66 ators, functions, nested loops to traverse and erase kernel data.
67 --eppic requires eppic_makedumpfile.so and eppic library. eppic_make‐
68 dumpfile.so can be built from makedumpfile source. Refer to
69 http://code.google.com/p/eppic/ to build eppic library libeppic.a and
70 for more information on writing eppic macros.
71 To analyze the first kernel's memory usage, makedumpfile can refer to
73 VMCOREINFO instead of VMLINUX. VMCOREINFO contains the first kernel's
74 information (structure size, field offset, etc.), and VMCOREINFO is
75 small enough to be included into the second kernel's initrd.
76 If the second kernel is running on its initrd without mounting a root
77 file system, makedumpfile cannot refer to VMLINUX because the second
78 kernel's initrd cannot include a large file like VMLINUX. To solve the
79 problem, makedumpfile makes VMCOREINFO beforehand, and it refers to
80 VMCOREINFO instead of VMLINUX while the second kernel is running.
81 VMCORE has contained VMCOREINFO since linux-2.6.24, and a user does not
82 need to specify neither -x nor -i option.
83 If the second kernel is running on its initrd without mounting any file
85 system, a user needs to transport the dump data to a remote host. To
86 transport the dump data by SSH, makedumpfile outputs the dump data in
87 the intermediate format (the flattened format) to the standard output.
88 By piping the output data to SSH, a user can transport the dump data to
89 a remote host. Note that analysis tools (crash utility before version
90 5.1.2 or GDB) cannot read the flattened format directly, so on a remote
91 host the received data in the flattened format needs to be rearranged
92 to a readable DUMPFILE format by makedumpfile (or makedumpfile-R.pl).
93 makedumpfile can read a DUMPFILE in the kdump-compressed format instead
95 of VMCORE and re-filter it. This feature is useful in situation that
96 users need to reduce the file size of DUMPFILE for sending it somewhere
97 by ftp/scp/etc. (If all of the page types, which are specified by a new
98 dump_level, are excluded from an original DUMPFILE already, a new DUMP‐
99 FILE is the same as an original DUMPFILE.)
100 For example, makedumpfile can create a DUMPFILE of dump_level 31 from
101 the one of dump_level 3 like the following:
102 Example:
103 # makedumpfile -c -d 3 /proc/vmcore dumpfile.1
104 # makedumpfile -c -d 31 dumpfile.1 dumpfile.2
105 makedumpfile can read VMCORE(s) in three kinds of sadump formats: sin‐
107 gle partition format, diskset format and media backup format, and can
108 convert each of them into kdump-compressed format with filtering and
109 compression processing. Note that for VMCORE(s) created by sadump, you
110 always need to pass VMLINUX with -x option. Also, to pass multiple
111 VMCOREs created on diskset configuration, you need to use --diskset
112 option.
113
116 -c,-l,-p
117 Compress dump data by each page using zlib for -c option, lzo
118 for -l option or snappy for -p option. (-l option needs
119 USELZO=on and -p option needs USESNAPPY=on when building)
120 A user cannot specify this option with -E option, because the
121 ELF format does not support compressed data.
122 Example:
123 # makedumpfile -c -d 31 -x vmlinux /proc/vmcore dumpfile
124 -d dump_level
127 Specify the type of unnecessary page for analysis.
128 Pages of the specified type are not copied to DUMPFILE. The page
129 type marked in the following table is excluded. A user can spec‐
130 ify multiple page types by setting the sum of each page type for
131 dump_level. The maximum of dump_level is 31. Note that a
132 dump_level for Xen dump filtering is 0 or 1 on a machine other
133 than x86_64 (On an x86_64 machine, it is possible to specify 2
134 or bigger as a dump_level).
135 If specifying multiple dump_levels with the delimiter ',', make‐
136 dumpfile retries to create a DUMPFILE by other dump_level when
137 "No space on device" error happens. For example, if dump_level
138 is "11,31" and makedumpfile fails by dump_level 11, makedumpfile
139 retries it by dump_level 31.
140 Example:
141 # makedumpfile -d 11 -x vmlinux /proc/vmcore dumpfile
142 # makedumpfile -d 11,31 -x vmlinux /proc/vmcore dumpfile
143 | |cache |cache | |
145 dump | zero |without|with | user | free
146 level | page |private|private| data | page
147 -------+------+-------+-------+------+------
148 0 | | | | |
149 1 | X | | | |
150 2 | | X | | |
151 3 | X | X | | |
152 4 | | X | X | |
153 5 | X | X | X | |
154 6 | | X | X | |
155 7 | X | X | X | |
156 8 | | | | X |
157 9 | X | | | X |
158 10 | | X | | X |
159 11 | X | X | | X |
160 12 | | X | X | X |
161 13 | X | X | X | X |
162 14 | | X | X | X |
163 15 | X | X | X | X |
164 16 | | | | | X
165 17 | X | | | | X
166 18 | | X | | | X
167 19 | X | X | | | X
168 20 | | X | X | | X
169 21 | X | X | X | | X
170 22 | | X | X | | X
171 23 | X | X | X | | X
172 24 | | | | X | X
173 25 | X | | | X | X
174 26 | | X | | X | X
175 27 | X | X | | X | X
176 28 | | X | X | X | X
177 29 | X | X | X | X | X
178 30 | | X | X | X | X
179 31 | X | X | X | X | X
180 -E Create DUMPFILE in the ELF format.
184 This option cannot be specified with either of -c option or -l
185 option, because the ELF format does not support compressed data.
186 Example:
187 # makedumpfile -E -d 31 -x vmlinux /proc/vmcore dumpfile
188 -f Force existing DUMPFILE to be overwritten.
191 Example:
192 # makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile
193 This command overwrites DUMPFILE even if it already exists.
194 -x VMLINUX
197 Specify the first kernel's VMLINUX with debug information to
198 analyze the first kernel's memory usage.
199 This option is necessary if VMCORE does not contain VMCOREINFO,
200 [-i VMCOREINFO] is not specified, and dump_level is 2 or more.
201 The page size of the first kernel and the second kernel should
202 match.
203 Example:
204 # makedumpfile -d 31 -x vmlinux /proc/vmcore dumpfile
205 -i VMCOREINFO
208 Specify VMCOREINFO instead of VMLINUX for analyzing the first
209 kernel's memory usage.
210 VMCOREINFO should be made beforehand by makedumpfile with -g
211 option, and it contains the first kernel's information.
212 This option is necessary if VMCORE does not contain VMCOREINFO,
213 [-x VMLINUX] is not specified, and dump_level is 2 or more.
214 Example:
215 # makedumpfile -d 31 -i vmcoreinfo /proc/vmcore dumpfile
216 -g VMCOREINFO
219 Generate VMCOREINFO from the first kernel's VMLINUX with debug
220 information.
221 VMCOREINFO must be generated on the system that is running the
222 first kernel. With -i option, a user can specify VMCOREINFO gen‐
223 erated on the other system that is running the same first ker‐
224 nel. [-x VMLINUX] must be specified.
225 Example:
226 # makedumpfile -g vmcoreinfo -x vmlinux
227 --config FILTERCONFIGFILE
230 Used in conjunction with -x VMLINUX option, to specify the fil‐
231 ter config file FILTERCONFIGFILE that contains erase commands to
232 filter out desired kernel data from vmcore while creating DUMP‐
233 FILE. For filter command syntax please refer to makedump‐
234 file.conf(5).
235 --eppic EPPICMACRO
238 Used in conjunction with -x VMLINUX option, to specify the eppic
239 macro file that contains filter rules or directory that contains
240 eppic macro files to filter out desired kernel data from vmcore
241 while creating DUMPFILE. When directory is specified, all the
242 eppic macros in the directory are processed.
243 -F Output the dump data in the flattened format to the standard
246 output for transporting the dump data by SSH.
247 Analysis tools (crash utility before version 5.1.2 or GDB) can‐
248 not read the flattened format directly. For analysis, the dump
249 data in the flattened format should be rearranged to a normal
250 DUMPFILE (readable with analysis tools) by -R option. By which
251 option is specified with -F option, the format of the rearranged
252 DUMPFILE is fixed. In other words, it is impossible to specify
253 the DUMPFILE format when the dump data is rearranged with -R
254 option. If specifying -E option with -F option, the format of
255 the rearranged DUMPFILE is the ELF format. Otherwise, it is the
256 kdump-compressed format. All the messages are output to standard
257 error output by -F option because standard output is used for
258 the dump data.
259 Example:
260 # makedumpfile -F -c -d 31 -x vmlinux /proc/vmcore \
261 | ssh user@host "cat > dumpfile.tmp"
262 # makedumpfile -F -c -d 31 -x vmlinux /proc/vmcore \
263 | ssh user@host "makedumpfile -R dumpfile"
264 # makedumpfile -F -E -d 31 -i vmcoreinfo /proc/vmcore \
265 | ssh user@host "makedumpfile -R dumpfile"
266 # makedumpfile -F -E --xen-vmcoreinfo VMCOREINFO /proc/vmcore \
267 | ssh user@host "makedumpfile -R dumpfile"
268 -R Rearrange the dump data in the flattened format from the stan‐
271 dard input to a normal DUMPFILE (readable with analysis tools).
272 Example:
273 # makedumpfile -R dumpfile < dumpfile.tmp
274 # makedumpfile -F -d 31 -x vmlinux /proc/vmcore \
275 | ssh user@host "makedumpfile -R dumpfile"
276 Instead of using -R option, a perl script "makedumpfile-R.pl"
278 rearranges the dump data in the flattened format to a normal
279 DUMPFILE, too. The perl script does not depend on architecture,
280 and most systems have perl command. Even if a remote host does
281 not have makedumpfile, it is possible to rearrange the dump data
282 in the flattened format to a readable DUMPFILE on a remote host
283 by running this script.
284 Example:
285 # makedumpfile -F -d 31 -x vmlinux /proc/vmcore \
286 | ssh user@host "makedumpfile-R.pl dumpfile"
287 --split
290 Split the dump data to multiple DUMPFILEs in parallel. If speci‐
291 fying DUMPFILEs on different storage devices, a device can share
292 I/O load with other devices and it reduces time for saving the
293 dump data. The file size of each DUMPFILE is smaller than the
294 system memory size which is divided by the number of DUMPFILEs.
295 This feature supports only the kdump-compressed format.
296 Example:
297 # makedumpfile --split -d 31 -x vmlinux /proc/vmcore dumpfile1
298 dumpfile2
299 --reassemble
302 Reassemble multiple DUMPFILEs, which are created by --split
303 option, into one DUMPFILE. dumpfile1 and dumpfile2 are reassem‐
304 bled into dumpfile on the following example.
305 Example:
306 # makedumpfile --reassemble dumpfile1 dumpfile2 dumpfile
307 -b <order>
310 Cache 2^order pages in ram when generating DUMPFILE before writ‐
311 ing to output. The default value is 4.
312 --cyclic-buffer buffer_size
315 Specify the buffer size in kilo bytes for analysis in the cyclic
316 mode. In the cyclic mode, the number of cycles is represented
317 as:
318 num_of_cycles = system_memory / (buffer_size * 1024 *
320 bit_per_bytes * page_size )
321 The lesser number of cycles, the faster working speed is
323 expected. By default, buffer_size will be calculated automati‐
324 cally depending on system memory size, so ordinary users don't
325 need to specify this option.
326 Example:
328 # makedumpfile --cyclic-buffer 1024 -d 31 -x vmlinux
329 /proc/vmcore dumpfile
330 --non-cyclic
333 Running in the non-cyclic mode, this mode uses the old filtering
334 logic same as v1.4.4 or before. If you feel the cyclic mode is
335 too slow, please try this mode.
336 Example:
337 # makedumpfile --non-cyclic -d 31 -x vmlinux /proc/vmcore dump‐
338 file
339 --non-mmap
342 Never use mmap(2) to read VMCORE even if it supports mmap(2).
343 Generally, reading VMCORE with mmap(2) is faster than without
344 it, so ordinary users don't need to specify this option. This
345 option is mainly for debugging.
346 Example:
347 # makedumpfile --non-mmap -d 31 -x vmlinux /proc/vmcore dumpfile
348 --xen-syms XEN-SYMS
351 Specify the XEN-SYMS with debug information to analyze the xen's
352 memory usage. This option extracts the part of xen and
353 domain-0. -E option must be specified with this option.
354 Example:
355 # makedumpfile -E --xen-syms xen-syms /proc/vmcore dumpfile
356 --xen-vmcoreinfo VMCOREINFO
359 Specify VMCOREINFO instead of XEN-SYMS for analyzing the xen's
360 memory usage.
361 VMCOREINFO should be made beforehand by makedumpfile with -g
362 option, and it contains the xen's information. -E option must
363 be specified with this option.
364 Example:
365 # makedumpfile -E --xen-vmcoreinfo VMCOREINFO /proc/vmcore dump‐
366 file
367 -X Exclude all the user domain pages from Xen kdump's VMCORE, and
370 extracts the part of xen and domain-0. If VMCORE contains VMCOR‐
371 EINFO for Xen, it is not necessary to specify --xen-syms and
372 --xen-vmcoreinfo. -E option must be specified with this option.
373 Example:
374 # makedumpfile -E -X /proc/vmcore dumpfile
375 --xen_phys_start xen_phys_start_address
378 This option is only for x86_64. Specify the
379 xen_phys_start_address, if the xen code/data is relocatable and
380 VMCORE does not contain xen_phys_start_address in the CRASHINFO.
381 xen_phys_start_address can be taken from the line of "Hypervisor
382 code and data" in /proc/iomem. For example, specify 0xcee00000
383 as xen_phys_start_address if /proc/iomem is the following:
384 -------------------------------------------------------
385 # cat /proc/iomem
386 ...
387 cee00000-cfd99999 : Hypervisor code and data
388 ...
389 -------------------------------------------------------
390 Example:
392 # makedumpfile -E -X --xen_phys_start 0xcee00000 /proc/vmcore
393 dumpfile
394 --message-level message_level
397 Specify the message types.
398 Users can restrict outputs printed by specifying message_level
399 with this option. The message type marked with an X in the fol‐
400 lowing table is printed. For example, according to the table,
401 specifying 7 as message_level means progress indicator, common
402 message, and error message are printed, and this is a default
403 value. Note that the maximum value of message_level is 31.
404 message | progress | common | error | debug | report
406 level | indicator| message | message | message | message
407 ---------+----------+---------+---------+---------+---------
408 0 | | | | |
409 1 | X | | | |
410 2 | | X | | |
411 3 | X | X | | |
412 4 | | | X | |
413 5 | X | | X | |
414 6 | | X | X | |
415 * 7 | X | X | X | |
416 8 | | | | X |
417 9 | X | | | X |
418 10 | | X | | X |
419 11 | X | X | | X |
420 12 | | | X | X |
421 13 | X | | X | X |
422 14 | | X | X | X |
423 15 | X | X | X | X |
424 16 | | | | | X
425 17 | X | | | | X
426 18 | | X | | | X
427 19 | X | X | | | X
428 20 | | | X | | X
429 21 | X | | X | | X
430 22 | | X | X | | X
431 23 | X | X | X | | X
432 24 | | | | X | X
433 25 | X | | | X | X
434 26 | | X | | X | X
435 27 | X | X | | X | X
436 28 | | | X | X | X
437 29 | X | | X | X | X
438 30 | | X | X | X | X
439 31 | X | X | X | X | X
440 --vtop virtual_address
443 This option is useful, when user debugs the translation problem
444 of virtual address. If specifing virtual_address, its physical
445 address is printed. It makes debugging easy by comparing the
446 output of this option with the one of "vtop" subcommand of the
447 crash utility. "--vtop" option only prints the translation out‐
448 put, and it does not affect the dumpfile creation.
449 --dump-dmesg
452 This option overrides the normal behavior of makedumpfile.
453 Instead of compressing and filtering a VMCORE to make it
454 smaller, it simply extracts the dmesg log from a VMCORE and
455 writes it to the specified LOGFILE. If a VMCORE does not contain
456 VMCOREINFO for dmesg, it is necessary to specfiy [-x VMLINUX] or
457 [-i VMCOREINFO].
458 Example:
460 # makedumpfile --dump-dmesg /proc/vmcore dmesgfile
461 # makedumpfile --dump-dmesg -x vmlinux /proc/vmcore dmesgfile
462 --diskset=VMCORE
465 Specify multiple VMCOREs created on sadump diskset configuration
466 the same number of times as the number of VMCOREs in increasing
467 order from left to right. VMCOREs are assembled into a single
468 DUMPFILE.
469 Example:
471 # makedumpfile -x vmlinux --diskset=vmcore1 --diskset=vmcore2
472 dumpfile
473 -D Print debugging message.
476 -h (--help)
479 Show help message and LZO/snappy support status (enabled/dis‐
480 abled).
481 -v Show the version of makedumpfile.
484
487 TMPDIR This environment variable is for a temporary memory bitmap file
488 only in the non-cyclic mode. If your machine has a lots of
489 memory and you use tmpfs on /tmp, makedumpfile can fail for a
490 little memory in the 2nd kernel because makedumpfile makes a
491 very large temporary memory bitmap file in this case. To avoid
492 this failure, you can set a TMPDIR environment variable. If you
493 do not set a TMPDIR environment variable, makedumpfile uses
494 /tmp directory for a temporary bitmap file as a default.
495
498 makedumpfile exits with the following value.
499 0 : makedumpfile succeeded.
501 1 : makedumpfile failed without the following reasons.
503 2 : makedumpfile failed due to the different version between VMLINUX
505 and VMCORE.
506 3 : makedumpfile failed due to the analysis error of the memory.
508
511 Written by Masaki Tachibana, and Ken'ichi Ohmichi.
512
515 crash(8), gdb(1), kexec(8), makedumpfile.conf(5)
516makedumpfile v1.5.6 23 Apr 2014 MAKEDUMPFILE(8)