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MAKEDUMPFILE(8)                          Linux System Administrator's Manual                          MAKEDUMPFILE(8)



NAME
       makedumpfile - make a small dumpfile of kdump

SYNOPSIS
       makedumpfile    [OPTION] [-x VMLINUX|-i VMCOREINFO] VMCORE DUMPFILE
       makedumpfile -F [OPTION] [-x VMLINUX|-i VMCOREINFO] VMCORE
       makedumpfile   [OPTION] -x VMLINUX [--config FILTERCONFIGFILE] [--eppic EPPICMACRO] VMCORE DUMPFILE
       makedumpfile -R DUMPFILE
       makedumpfile --split [OPTION] [-x VMLINUX|-i VMCOREINFO] VMCORE DUMPFILE1 DUMPFILE2 [DUMPFILE3 ..]
       makedumpfile [OPTION] [-x VMLINUX|-i VMCOREINFO] --num-threads THREADNUM VMCORE DUMPFILE
       makedumpfile --reassemble DUMPFILE1 DUMPFILE2 [DUMPFILE3 ..] DUMPFILE
       makedumpfile -g VMCOREINFO -x VMLINUX
       makedumpfile    [OPTION] [--xen-syms XEN-SYMS|--xen-vmcoreinfo VMCOREINFO] VMCORE DUMPFILE
       makedumpfile --dump-dmesg [-x VMLINUX|-i VMCOREINFO] VMCORE LOGFILE
       makedumpfile    [OPTION] -x VMLINUX --diskset=VMCORE1 --diskset=VMCORE2 [--diskset=VMCORE3 ..] DUMPFILE
       makedumpfile -h
       makedumpfile -v

DESCRIPTION
       With kdump, the memory image of the first kernel (called "panicked kernel") can be taken as /proc/vmcore while
       the second  kernel  (called  "kdump  kernel"  or  "capture  kernel")  is  running.  This  document  represents
       /proc/vmcore  as VMCORE. makedumpfile makes a small DUMPFILE by compressing dump data or by excluding unneces‐
       sary pages for analysis, or both. makedumpfile needs the first kernel's debug information, so that it can dis‐
       tinguish  unnecessary  pages  by analyzing how the first kernel uses the memory.  The information can be taken
       from VMLINUX or VMCOREINFO.

       makedumpfile can exclude the following types of pages while copying VMCORE to DUMPFILE, and a user can  choose
       which type of pages will be excluded.
       - Pages filled with zero
       - Cache pages without private flag (non-private cache)
       - Cache pages with private flag (private cache)
       - User process data pages
       - Free pages

       makedumpfile provides two DUMPFILE formats (the ELF format and the kdump-compressed format). By default, make‐
       dumpfile makes a DUMPFILE in the kdump-compressed format. The kdump-compressed format is  readable  only  with
       the  crash utility, and it can be smaller than the ELF format because of the compression support. The ELF for‐
       mat is readable with GDB and the crash utility.  If a user wants to use GDB, DUMPFILE format has to be explic‐
       itly specified to be the ELF format.

       Apart from the exclusion of unnecessary pages mentioned above, makedumpfile allows user to filter out targeted
       kernel data. The filter config file can be used to specify kernel/module symbols and its members that need  to
       be  filtered out through the erase command syntax. makedumpfile reads the filter config and builds the list of
       memory addresses and its sizes after processing filter commands. The memory locations that require to be  fil‐
       tered out are then poisoned with character 'X' (58 in Hex). Refer to makedumpfile.conf(5) for file format.

       Eppic  macros  can also be used to specify kernel symbols and its members that need to be filtered. Eppic pro‐
       vides C semantics including language constructs such as conditional statements, logical and arithmetic  opera‐
       tors,  functions,  nested  loops to traverse and erase kernel data. --eppic requires eppic_makedumpfile.so and
       eppic   library.   eppic_makedumpfile.so   can   be    built    from    makedumpfile    source.    Refer    to
       http://code.google.com/p/eppic/  to  build  eppic library libeppic.a and for more information on writing eppic
       macros.

       To analyze the first kernel's memory usage, makedumpfile can refer to VMCOREINFO instead of  VMLINUX.  VMCORE‐
       INFO  contains  the  first  kernel's information (structure size, field offset, etc.), and VMCOREINFO is small
       enough to be included into the second kernel's initrd.
       needs to be rearranged to a readable DUMPFILE format by makedumpfile (or makedumpfile-R.pl).

       makedumpfile  can read a DUMPFILE in the kdump-compressed format instead of VMCORE and re-filter it. This fea‐
       ture is useful in situation that users need to reduce the file size of DUMPFILE for sending  it  somewhere  by
       ftp/scp/etc. (If all of the page types, which are specified by a new dump_level, are excluded from an original
       DUMPFILE already, a new DUMPFILE is the same as an original DUMPFILE.)
       For example, makedumpfile can create a DUMPFILE of dump_level 31 from the one of dump_level 3 like the follow‐
       ing:
       Example:
       # makedumpfile -c -d 3 /proc/vmcore dumpfile.1
       # makedumpfile -c -d 31 dumpfile.1 dumpfile.2

       makedumpfile  can read VMCORE(s) in three kinds of sadump formats: single partition format, diskset format and
       media backup format, and can convert each of them into kdump-compressed format with filtering and  compression
       processing.  Note  that for VMCORE(s) created by sadump, you always need to pass VMLINUX with -x option. Also,
       to pass multiple VMCOREs created on diskset configuration, you need to use --diskset option.


OPTIONS
       -c,-l,-p
              Compress dump data by each page using zlib for -c option, lzo for -l option or snappy  for  -p  option.
              (-l option needs USELZO=on and -p option needs USESNAPPY=on when building)
              A  user  cannot  specify this option with -E option, because the ELF format does not support compressed
              data.
              Example:
              # makedumpfile -c -d 31 -x vmlinux /proc/vmcore dumpfile


       -d dump_level
              Specify the type of unnecessary page for analysis.
              Pages of the specified type are not copied to DUMPFILE. The page type marked in the following table  is
              excluded.  A  user can specify multiple page types by setting the sum of each page type for dump_level.
              The maximum of dump_level is 31. Note that a dump_level for Xen dump filtering is 0 or 1 on  a  machine
              other  than  x86_64.  On a x86_64 machine, even 2 or bigger dump level will be effective if you specify
              domain-0's vmlinux with -x option.  Then the pages are excluded only from domain-0.
              If specifying multiple dump_levels with the delimiter ',', makedumpfile retries to create a DUMPFILE by
              other  dump_level  when  "No  space on device" error happens. For example, if dump_level is "11,31" and
              makedumpfile fails by dump_level 11, makedumpfile retries it by dump_level 31.
              Example:
              # makedumpfile -d 11 -x vmlinux /proc/vmcore dumpfile
              # makedumpfile -d 11,31 -x vmlinux /proc/vmcore dumpfile
              Base level:
              dump_level consists of five bits, so there are five base levels to  specify  the  type  of  unnecessary
              page.
                    1 : Exclude the pages filled with zero.
                    2 : Exclude the non-private cache pages.
                    4 : Exclude all cache pages.
                    8 : Exclude the user process data pages.
                   16 : Exclude the free pages.

              Here is the all combinations of the bits.

                     |      |non-   |       |      |
                dump | zero |private|private| user | free

                  10 |      |   X   |       |  X   |
                  11 |  X   |   X   |       |  X   |
                  12 |      |   X   |   X   |  X   |
                  13 |  X   |   X   |   X   |  X   |
                  14 |      |   X   |   X   |  X   |
                  15 |  X   |   X   |   X   |  X   |
                  16 |      |       |       |      |  X
                  17 |  X   |       |       |      |  X
                  18 |      |   X   |       |      |  X
                  19 |  X   |   X   |       |      |  X
                  20 |      |   X   |   X   |      |  X
                  21 |  X   |   X   |   X   |      |  X
                  22 |      |   X   |   X   |      |  X
                  23 |  X   |   X   |   X   |      |  X
                  24 |      |       |       |  X   |  X
                  25 |  X   |       |       |  X   |  X
                  26 |      |   X   |       |  X   |  X
                  27 |  X   |   X   |       |  X   |  X
                  28 |      |   X   |   X   |  X   |  X
                  29 |  X   |   X   |   X   |  X   |  X
                  30 |      |   X   |   X   |  X   |  X
                  31 |  X   |   X   |   X   |  X   |  X



       -E     Create DUMPFILE in the ELF format.
              This  option cannot be specified with the -c, -l or -p options, because the ELF format does not support
              compressed data.
              Example:
              # makedumpfile -E -d 31 -x vmlinux /proc/vmcore dumpfile


       -f     Force existing DUMPFILE to be overwritten.
              Example:
              # makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile
              This command overwrites DUMPFILE even if it already exists.


       -x VMLINUX
              Specify the first kernel's VMLINUX with debug information to analyze the first kernel's memory usage.
              This option is necessary if VMCORE does not contain VMCOREINFO, [-i VMCOREINFO] is not  specified,  and
              dump_level is 2 or more.
              The page size of the first kernel and the second kernel should match.
              Example:
              # makedumpfile -d 31 -x vmlinux /proc/vmcore dumpfile


       -i VMCOREINFO
              Specify VMCOREINFO instead of VMLINUX for analyzing the first kernel's memory usage.
              VMCOREINFO should be made beforehand by makedumpfile with -g option, and it contains the first kernel's
              information.
              This option is necessary if VMCORE does not contain VMCOREINFO, [-x  VMLINUX]  is  not  specified,  and
              dump_level is 2 or more.
              Example:

       --config FILTERCONFIGFILE
              Used  in  conjunction  with  -x VMLINUX option, to specify the filter config file FILTERCONFIGFILE that
              contains erase commands to filter out desired kernel data from vmcore while creating DUMPFILE. For fil‐
              ter command syntax please refer to makedumpfile.conf(5).


       --eppic EPPICMACRO
              Used  in conjunction with -x VMLINUX option, to specify the eppic macro file that contains filter rules
              or directory that contains eppic macro files to filter out desired kernel data from vmcore while creat‐
              ing DUMPFILE.  When directory is specified, all the eppic macros in the directory are processed.


       -F     Output  the  dump data in the flattened format to the standard output for transporting the dump data by
              SSH.
              Analysis tools (crash utility before version 5.1.2 or GDB) cannot read the flattened  format  directly.
              For analysis, the dump data in the flattened format should be rearranged to a normal DUMPFILE (readable
              with analysis tools) by -R option. By which option is specified with -F option, the format of the rear‐
              ranged  DUMPFILE  is  fixed.   In other words, it is impossible to specify the DUMPFILE format when the
              dump data is rearranged with -R option. If specifying -E option with -F option, the format of the rear‐
              ranged  DUMPFILE  is the ELF format. Otherwise, it is the kdump-compressed format. All the messages are
              output to standard error output by -F option because standard output is used for the dump data.
              Example:
              # makedumpfile -F -c -d 31 -x vmlinux /proc/vmcore \
              | ssh user@host "cat > dumpfile.tmp"
              # makedumpfile -F -c -d 31 -x vmlinux /proc/vmcore \
              | ssh user@host "makedumpfile -R dumpfile"
              # makedumpfile -F -E -d 31 -i vmcoreinfo  /proc/vmcore \
              | ssh user@host "makedumpfile -R dumpfile"
              # makedumpfile -F -E --xen-vmcoreinfo VMCOREINFO /proc/vmcore \
              | ssh user@host "makedumpfile -R dumpfile"


       -R     Rearrange the dump data in the flattened format from the standard input to a normal DUMPFILE  (readable
              with analysis tools).
              Example:
              # makedumpfile -R dumpfile < dumpfile.tmp
              # makedumpfile -F -d 31 -x vmlinux /proc/vmcore \
              | ssh user@host "makedumpfile -R dumpfile"

              Instead of using -R option, a perl script "makedumpfile-R.pl" rearranges the dump data in the flattened
              format to a normal DUMPFILE, too. The perl script does not depend on  architecture,  and  most  systems
              have  perl  command.  Even if a remote host does not have makedumpfile, it is possible to rearrange the
              dump data in the flattened format to a readable DUMPFILE on a remote host by running this script.
              Example:
              # makedumpfile -F -d 31 -x vmlinux /proc/vmcore \
              | ssh user@host "makedumpfile-R.pl dumpfile"


       --split
              Split the dump data to multiple DUMPFILEs in parallel. If specifying  DUMPFILEs  on  different  storage
              devices,  a  device can share I/O load with other devices and it reduces time for saving the dump data.
              The file size of each DUMPFILE is smaller than the system memory size which is divided by the number of
              DUMPFILEs. This feature supports only the kdump-compressed format.
              Example:
              Reassemble  multiple  DUMPFILEs,  which are created by --split option, into one DUMPFILE. dumpfile1 and
              dumpfile2 are reassembled into dumpfile on the following example.
              Example:
              # makedumpfile --reassemble dumpfile1 dumpfile2 dumpfile


       -b <order>
              Cache 2^order pages in ram when generating DUMPFILE before writing to output.  The default value is 4.


       --cyclic-buffer buffer_size
              Specify the buffer size in kilo bytes for bitmap data.  Filtering processing will be divided into multi
              cycles to fix the memory consumption, the number of cycles is represented as:

                  num_of_cycles = system_memory / (buffer_size * 1024 * bit_per_bytes * page_size )

              The  lesser  number  of  cycles, the faster working speed is expected.  By default, buffer_size will be
              calculated automatically depending on system memory size, so ordinary users don't need to specify  this
              option.

              Example:
              # makedumpfile --cyclic-buffer 1024 -d 31 -x vmlinux /proc/vmcore dumpfile


       --splitblock-size splitblock_size
              Specify  the  splitblock size in kilo bytes for analysis with --split.  If --splitblock N is specified,
              difference of each splitted dumpfile size is at most N kilo bytes.
              Example:
              # makedumpfile --splitblock-size 1024 -d 31 -x vmlinux --split /proc/vmcore dumpfile1 dumpfile2



       --work-dir
              Specify the working directory for the temporary bitmap file.  If this option isn't specified, the  bit‐
              map will be saved on memory.  Filtering processing has to do 2 pass scanning to fix the memory consump‐
              tion, but it can be avoided by using working directory on file system.  So if you specify this  option,
              the filtering speed may be bit faster.

              Example:
              # makedumpfile --work-dir /tmp -d 31 -x vmlinux /proc/vmcore dumpfile


       --non-mmap
              Never  use  mmap(2) to read VMCORE even if it supports mmap(2).  Generally, reading VMCORE with mmap(2)
              is faster than without it, so ordinary users don't need to specify this option.  This option is  mainly
              for debugging.
              Example:
              # makedumpfile --non-mmap -d 31 -x vmlinux /proc/vmcore dumpfile


       --xen-syms XEN-SYMS
              Specify  the  XEN-SYMS  with debug information to analyze the xen's memory usage.  This option extracts
              the part of xen and domain-0.
              Example:
              If VMCORE contains VMCOREINFO for Xen, it is not necessary to specify --xen-syms and --xen-vmcoreinfo.
              Example:
              # makedumpfile -E -X /proc/vmcore dumpfile


       --xen_phys_start xen_phys_start_address
              This option is only for x86_64.  Specify the xen_phys_start_address, if the xen code/data  is  relocat‐
              able  and  VMCORE does not contain xen_phys_start_address in the CRASHINFO.  xen_phys_start_address can
              be taken from the line of "Hypervisor code and data" in /proc/iomem. For example, specify 0xcee00000 as
              xen_phys_start_address if /proc/iomem is the following:
                -------------------------------------------------------
                # cat /proc/iomem
                ...
                  cee00000-cfd99999 : Hypervisor code and data
                ...
                -------------------------------------------------------

              Example:
              # makedumpfile -E -X --xen_phys_start 0xcee00000 /proc/vmcore dumpfile


       --message-level message_level
              Specify the message types.
              Users  can  restrict  outputs  printed  by  specifying message_level with this option. The message type
              marked with an X in the following table is printed. For example, according to the table,  specifying  7
              as message_level means progress indicator, common message, and error message are printed, and this is a
              default value. Note that the maximum value of message_level is 31.

               message | progress | common  | error   | debug   | report
               level   | indicator| message | message | message | message
              ---------+----------+---------+---------+---------+---------
                     0 |          |         |         |         |
                     1 |    X     |         |         |         |
                     2 |          |    X    |         |         |
                     3 |    X     |    X    |         |         |
                     4 |          |         |    X    |         |
                     5 |    X     |         |    X    |         |
                     6 |          |    X    |    X    |         |
                   * 7 |    X     |    X    |    X    |         |
                     8 |          |         |         |    X    |
                     9 |    X     |         |         |    X    |
                    10 |          |    X    |         |    X    |
                    11 |    X     |    X    |         |    X    |
                    12 |          |         |    X    |    X    |
                    13 |    X     |         |    X    |    X    |
                    14 |          |    X    |    X    |    X    |
                    15 |    X     |    X    |    X    |    X    |
                    16 |          |         |         |         |    X
                    17 |    X     |         |         |         |    X
                    18 |          |    X    |         |         |    X
                    19 |    X     |    X    |         |         |    X
                    20 |          |         |    X    |         |    X
                    21 |    X     |         |    X    |         |    X
                    22 |          |    X    |    X    |         |    X

              This option is useful, when user debugs the translation problem of virtual address. If  specifing  vir‐
              tual_address,  its physical address is printed. It makes debugging easy by comparing the output of this
              option with the one of "vtop" subcommand of the crash utility.  "--vtop" option only prints the  trans‐
              lation output, and it does not affect the dumpfile creation.


       --dump-dmesg
              This  option  overrides  the  normal  behavior of makedumpfile.  Instead of compressing and filtering a
              VMCORE to make it smaller, it simply extracts the dmesg log from a VMCORE and writes it to  the  speci‐
              fied  LOGFILE.  If  a  VMCORE  does  not  contain  VMCOREINFO for dmesg, it is necessary to specfiy [-x
              VMLINUX] or [-i VMCOREINFO].

              Example:
              # makedumpfile --dump-dmesg /proc/vmcore dmesgfile
              # makedumpfile --dump-dmesg -x vmlinux /proc/vmcore dmesgfile



       --mem-usage
              This option is only for x86_64.  This option is used to show the page numbers of current system in dif‐
              ferent  use.  It should be executed in 1st kernel. By the help of this, user can know how many pages is
              dumpable when different dump_level is specified. It analyzes the 'System Ram' and 'kernel text' program
              segment  of  /proc/kcore  excluding the crashkernel range, then calculates the page number of different
              kind per vmcoreinfo. So currently /proc/kcore need be specified explicitly.

              Example:
              # makedumpfile --mem-usage /proc/kcore



       --diskset=VMCORE
              Specify multiple VMCOREs created on sadump diskset configuration the same number of times as the number
              of VMCOREs in increasing order from left to right.  VMCOREs are assembled into a single DUMPFILE.

              Example:
              # makedumpfile -x vmlinux --diskset=vmcore1 --diskset=vmcore2 dumpfile


       -D     Print debugging message.


       -h (--help)
              Show help message and LZO/snappy support status (enabled/disabled).


       -v     Show the version of makedumpfile.


ENVIRONMENT VARIABLES
       TMPDIR  This  environment  variable  is used in 1st kernel environment for a temporary memory bitmap file.  If
               your machine has a lots of memory and you use small tmpfs on /tmp, makedumpfile can fail for a  little
               memory  because  makedumpfile  makes  a very large temporary memory bitmap file in this case. To avoid
               this failure, you should specify --work-dir option to use file system on storage for the bitmap file.


       Written by Masaki Tachibana, and Ken'ichi Ohmichi.


SEE ALSO
       crash(8), gdb(1), kexec(8), makedumpfile.conf(5)




makedumpfile v1.6.0                                   9 Jun 2016                                      MAKEDUMPFILE(8)