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 -R DUMPFILE makedumpfile --split [OPTION] [-x VMLINUX|-i VMCOREINFO] VMCORE DUMP- FILE1 DUMPFILE2 [DUMPFILE3 ..] makedumpfile --reassemble DUMPFILE1 DUMPFILE2 [DUMPFILE3 ..] DUMPFILE makedumpfile -g VMCOREINFO -x VMLINUX makedumpfile -E [--xen-syms XEN-SYMS|--xen-vmcoreinfo VMCOREINFO] VMCORE DUMPFILE makedumpfile --dump-dmesg [-x VMLINUX|-i VMCOREINFO] VMCORE LOGFILE 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 unnecessary pages for analysis,
or both. makedumpfile needs the first kernel's debug information, so
that it can distinguish 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
- User process data pages
- Free pages
makedumpfile provides two DUMPFILE formats (the ELF format and the
kdump-compressed format). By default, makedumpfile 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 format is readable with GDB
and the crash utility. If a user wants to use GDB, DUMPFILE format has
to be explicitly specified to be the ELF format.
To analyze the first kernel's memory usage, makedumpfile can refer to
VMCOREINFO instead of VMLINUX. VMCOREINFO 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.
If the second kernel is running on its initrd without mounting a root
file system, makedumpfile cannot refer to VMLINUX because the second
kernel's initrd cannot include a large file like VMLINUX. To solve the
problem, makedumpfile makes VMCOREINFO beforehand, and it refers to
VMCOREINFO instead of VMLINUX while the second kernel is running.
VMCORE has contained VMCOREINFO since linux-2.6.24, and a user does not
need to specify neither -x nor -i option.
If the second kernel is running on its initrd without mounting any file
system, a user needs to transport the dump data to a remote host. To
transport the dump data by SSH, makedumpfile outputs the dump data in
the intermediate format (the flattened format) to the standard output.
By piping the output data to SSH, a user can transport the dump data to
a remote host. Note that analysis tools cannot read the flattened format directly, so on a remote host the received data in the flattened
format 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 feature 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 following:
Example:
# makedumpfile -c -d 3 /proc/vmcore dumpfile.1
# makedumpfile -c -d 31 dumpfile.1 dumpfile.2
OPTIONS
- -c Compress dump data by each page.
- 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 an x86_64 machine, it is possible to specify 2 or bigger as a dump_level).
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
dump | zero | cache|cache | user | free - level | page | page |private| data | page
- -------+------+------+-------+------+------
- 0 | | | | |
1 | X | | | |
2 | | X | | |
3 | X | X | | |
4 | | X | X | |
5 | X | X | X | |
6 | | X | X | |
7 | X | X | X | |
8 | | | | X |
9 | X | | | X | - 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 -c option, 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:
# makedumpfile -d 31 -i vmcoreinfo /proc/vmcore dumpfile - -g VMCOREINFO
- Generate VMCOREINFO from the first kernel's VMLINUX with debug
information.
VMCOREINFO must be generated on the system that is running the first kernel. With -i option, a user can specify VMCOREINFO generated on the other system that is running the same first kernel. [-x VMLINUX] must be specified.
Example:
# makedumpfile -g vmcoreinfo -x vmlinux - -F Output the dump data in the flattened format to the standard
- output for transporting the dump data by SSH.
Analysis tools 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 rearranged 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 rearranged 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 stan
- dard 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:
# makedumpfile --split -d 31 -x vmlinux /proc/vmcore dumpfile1 dumpfile2 - --reassemble
- 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 - --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. -E option must be specified with this option.
Example:
# makedumpfile -E --xen-syms xen-syms /proc/vmcore dumpfile - --xen-vmcoreinfo VMCOREINFO
- Specify VMCOREINFO instead of XEN-SYMS for analyzing the xen's
memory usage.
VMCOREINFO should be made beforehand by makedumpfile with -g option, and it contains the xen's information. -E option must be specified with this option.
Example:
# makedumpfile -E --xen-vmcoreinfo VMCOREINFO /proc/vmcore dumpfile - -X Exclude all the user domain pages from Xen kdump's VMCORE, and
- extracts the part of xen and domain-0. If VMCORE contains VMCOREINFO for Xen, it is not necessary to specify --xen-syms and
--xen-vmcoreinfo. -E option must be specified with this option.
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 relocatable 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
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
29 | X | | X | X | X
30 | | X | X | X | X
31 | X | X | X | X | X - --vtop virtual_address
- This option is useful, when user debugs the translation problem of virtual address. If specifing virtual_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 translation 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 specified 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 - -D Print debugging message.
- -h Show help message.
- -v Show the version of makedumpfile.
DIAGNOSTICS
makedumpfile exits with the following value.
0 : makedumpfile succeeded.
1 : makedumpfile failed without the following reasons.
2 : makedumpfile failed due to the different version between VMLINUX
and VMCORE.
3 : makedumpfile failed due to the analysis error of the memory.
AUTHORS
Written by Masaki Tachibana, and Ken'ichi Ohmichi.