KDUMPTOOL(8) User Manuals KDUMPTOOL(8)NAMEkdumptool - Binary to support kdump saving and loading
SYNOPSISkdumptool [globals] command [options] [arguments]
DESCRIPTIONkdumptool provides various subcommands to support following actions for
kdump. It can:
· help to identify a kernel (whether it's relocatable or not, whether
it's ELF or x86-style independent of the file name),
· save a dump over various transports (local file, SSH2, FTP, NFS,
SMB),
· copy the kernel including debugging information from one directory
to the dump directory over the same transports as the dump itself,
· delete old dumps,
· read the VMCOREINFO (see makedumpfile(8) of kernel core dumps),
· show the progress over the keyboard LED.
Because most functionality is needed in the initrd, the design decision
was to provide that functionality in one binary without huge
dependencies and without a scripting language.
USAGE
To select which functionality is needed, one has to provide a command.
So, for example kdump save_dump and kdump copy_kernel is used to copy
the kernel. There are global options which are valid for all
(sub)commands and there are normal options which are only valid for a
specific command. Also, the command can take an arbitrary number of
arguments.
Additional to the command line options described in that manual page,
the behavior is influenced by configuration options in
/etc/sysconfig/kdump (or a different configuration file specified with
the -F (--configfile) option. Please read kdump(5) for documentation
about the configuration options.
GLOBAL OPTIONS
All option parsing is done via the getopt_long(5) function, and
therefore follows all standard command line parsing rules.
-h | --help
Shows help output and exits.
-v | --version
Shows version information and exits.
-b | --background
Run in daemon mode. This option is useful for the led_blink
subcommand.
-D | --debug
Prints debugging information (to stderr). If the output is
redirected to a terminal, then the various levels of debug
information are colored. Use -L (--logfile) to redirect the debug
output to a file.
-L filename | --logfile filename
Redirects the debugging output to the logfile specified with
filename.
-F filename | --configfile filename
Use a different configuration file instead of /etc/sysconfig/kdump.
-C filename | --cmdline filename
Modify the configuration with options read from filename, which is
treated as a kernel-style command line (e.g. /proc/cmdline). This
file is read after the main configuration file, so file options can
be overridden on the kernel command line.
IDENTIFYING A KERNEL
When finding a kernel that is suitable for kdump on the system, it's
necessary to know if that is a relocatable kernel. Historically, on
every platform except Itanium (IA64) kdump used a special kernel
compiled with another start address. That kernel had always "kdump" in
its name on SUSE systems. If such a kernel is found, that kernel is
preferred. However, if there is no such kernel, the kdump init script
(/etc/init.d/kdump) looks for normal kernels that are relocatable.
Syntax
kdumptool [globals] identify_kernel [-r] [-t]
It's necessary to provide either -r, -t or both.
Options
-r | --relocatable
Checks if the kernel is relocatable. If it is, it prints the string
Relocatable on stdout and exits with error code 0. If it's not
relocatable, then it prints Not relocatable and exits with 2.
-t | --type
Prints the type of the kernel. There are following types: x86 for
the bzImage format, ELF for a normal ELF binary and ELF gzip for
gzipped ELF binary.
DUMP SAVING
This command is used to save the dump to the specified KDUMP_DUMPDIR in
the configuration file with KDUMP_DUMPLEVEL in KDUMP_DUMPFORMAT.
When KDUMP_DUMPFORMAT is not "ELF" and the KDUMP_DUMPLEVEL is not 0,
the makedumpfile tool will be used to save the dump. For NFS and CIFS,
kernel support of mounting these shares is required. For NFS, the
showmount tool is required to check the exported file systems first.
This command also checks if the dump is too large to fit on disk (see
KDUMP_FREE_DISK_SIZE). If that is the case, the dump is deleted
afterwards. It's not possible to know the dump size in advance (if dump
filtering and/or dump compression is used).
After the dump has been saved, a notification email is sent via the
SMTP server specified as KDUMP_SMTP_SERVER (with the authentication
credentials specified as KDUMP_SMTP_USER and KDUMP_SMTP_USER) to the
mail addresses specified in KDUMP_NOTIFICATION_TO and
KDUMP_NOTIFICATION_CC. You can skip the mail part with the --nomail
option. Also, if you don't specify an SMTP server or a recipient, the
mail part is silently skipped.
Syntax
kdumptool [globals] save_dump [-u dumpfile] [-R root] [-k ver] [-q
fqdn]
Options
-u dumpfile | --dump dumpfile
Don't use /proc/vmcore as dump file but dumpfile. This is mostly
for debugging.
-R root | --root root
Use root instead of / as root directory. That option is useful in
initrd where the system root is not mounted to / but needs to be
mounted externally.
-k version | --kernelversion version
Use version as kernel version (which is necessary if the dump
saving process also copies the kernel binary) instead of the
auto-detected one via VMCOREINFO.
-H hostname | --hostname hostname
Use hostname as host name in the README.txt file (in the dump
directory). This is because the initrd often lacks proper network
configuration, and we want the hostname of the old system in that
README.txt file, not the initrd hostname (which may be an DHCP
auto-generated host name).
-M | --nomail
Don't send the notification email even if mail has been configured
in the configuration file.
LED BLINKING
To indicate that kdump initrd is booted, the keyboard LEDs should be
blinking because VGA may be broken when dumping from X. That subcommand
is used to achieve that.
The command can only be executed as root. Consider using the -b
(--background) option.
Syntax
kdumptool [globals] led_blink [-i interval]
Options
-i interval | --interval interval
Use interval ms for the blink interval instead of the default 250
ms.
PRINTING VMCOREINFO
In current kernel versions (starting from 2.6.25), the /proc/vmcore has
a new PT_NOTE section called VMCOREINFO. This is a textual
representation of key/value pairs read from makedumpfile to get some
parameters of the running kernel in the crashed environment. This
mechanism replaces the old VMCOREINFO file.
Syntax
kdumptool [globals] read_vmcoreinfo [-u dumpfile] [key]
When no key is specified, this command just prints all key/value pairs
in the form KEY=VALUE. The order is random and has nothing to do with
the order the values appear in the PT_NOTE section.
Options
-u dumpfile | --dump dumpfile
Don't use /proc/vmcore as dump file but dumpfile. This is mostly
for debugging.
DELETE OLD DUMPS
The delete_dumps subcommands deletes as many old dumps in KDUMP_SAVEDIR
as specified in KDUMP_KEEP_OLD_DUMPS.
Syntax
kdumptool [globals] delete_dumps [-y] [-R root]
Options
-y | --dry-run
Don't delete anything, just print out what would be deleted.
-R root | --root root
Use root instead of / as root directory. That option is useful in
initrd where the system root is not mounted to / but needs to be
mounted externally.
PRINT DUMP TARGET
For usage in scripts, the target URL can be printed and parsed by
kdumptool.
Syntax
kdumptool [globals] print_target [-R root]
Options
-R root | --root root
Use root instead of / as root directory. That option is useful in
initrd where the system root is not mounted to / but needs to be
mounted externally.
PRINT KERNEL CONFIGURATION
For kernels that have been compiled with CONFIG_IKCONFIG (usually also
with CONFIG_IKCONFIG_PROC to display the kernel configuration in the
running kernel in /proc/config.gz), that command dumps the embedded
kernel configuration from a kernel image to standard output.
All usual kernel image formats (ELF, compressed ELF, bzImage) are
supported.
Syntax
kdumptool [globals] read_ikconfig kernelimage
DUMP KDUMPTOOL CONFIGURATION
All configuration variables can be dumped to the standard output in a
form that can be process by a shell or that can be passed as kernel
parameters.
Syntax
kdumptool [globals] dump_config [-f format]
Options
-f format | --format format
Use the specified output format. It must be one of:
shell
The output can be read as a shell script. (default)
kernel
The output can be passed as a kernel parameter.
-u usage | --usage usage
Show only configuration variables that are used for a specific
stage. It is possible to specify multiple stages delimited by
commas. Recognized stages are:
mkinitrd
Variables which control how the kdump initrd is created, e.g.
which driver modules must be included.
kexec
Variables which are needed when loading the secondary kernel
with kexec. Note that fadump does not use these variables.
dump
Variables used in the secondary kernel when saving the dump.
all
Show all variables. (default)
MODIFY MULTIPATH CONFIGURATION
If multipath devices are used on a machine, then they should be also
configured in the dump kernel. However, each multipath device needs
some amount of RAM at run time, increasing the necessary size of the
crash reserved area. That way it is even possible to exceed the maximum
size of that area on machines with a very large number of multipath
devices,
This subcommand reads an existing multipath configuration on standard
input, blacklists all devices except those specified on the command
line, and sends the modified configuration to standard output. This
allows to let the dump kernel initialize only multipath devices that
are necessary for saving the dump.
Syntax
kdumptool [globals] multipath device[...]
device is a multipath device specification (e.g. "wwid
360060e801531f800000131f80000a001"). See multipath.conf(5) for details.
RETURN VALUE
0
Success.
255
Unknown Error.
2
Kernel has been identified but is not relocatable.
FILES
/etc/sysconfig/kdump
Configuration file, see kdump(5).
BUGS
Please report bugs and enhancement requests at
https://bugzilla.novell.com.
COPYING
Copyright (c) 2008 Bernhard Walle <bwalle@suse.de>. Free use of this
software is granted under the terms of the GNU General Public License
(GPL), version 2 or later.
SEE ALSOkexec(8), kdump(5), makedumpfile(8), http://en.opensuse.org/Kdump
kdump 0.8.4 06/14/2013 KDUMPTOOL(8)
