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 --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 [
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 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 without private pages
- All cache pages with private 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.
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 filtered 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 provides C semantics including language constructs
such as conditional statements, logical and arithmetic operators, 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.
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 (crash utility before version 5.1.2 or GDB) 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
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 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
| |cache |cache | |
dump | zero |without|with | user | free
level | page |private|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 either of -c option or -l 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
- --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
filter 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 creating
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 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 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:
# 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
- --cyclic-buffer buffer_size
- Specify the buffer size in kilo bytes for analysis in the cyclic mode.
Actually, the double of buffer_size kilo bytes will be allocated in
memory. In the cyclic mode, 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
- --non-cyclic
- Running in the non-cyclic mode, this mode uses the old filtering logic
same as v1.4.4 or before. If you feel the cyclic mode is too slow, please
try this mode.
Example:
# makedumpfile --non-cyclic -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. -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
- --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
- Show help message and LZO/snappy support status (enabled/disabled).
- -v
- Show the version of makedumpfile.
ENVIRONMENT VARIABLES¶
- TMPDIR
- This environment variable is for a temporary memory bitmap file only in
the non-cyclic mode. If your machine has a lots of memory and you use
tmpfs on /tmp, makedumpfile can fail for a little memory in the 2nd kernel
because makedumpfile makes a very large temporary memory bitmap file in
this case. To avoid this failure, you can set a TMPDIR environment
variable. If you do not set a TMPDIR environment variable, makedumpfile
uses /tmp directory for a temporary bitmap file as a default.
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.
SEE ALSO¶
crash(8),
gdb(1),
kexec(8),
makedumpfile.conf(5)