Ubuntu Manpage: kdump-config - configure kdump, check status, or save a vmcore file

Provided by: kdump-tools_1.6.5-1ubuntu1~18.04.7_amd64

NAME

       kdump-config - configure kdump, check status, or save a vmcore file

SYNOPSIS

       kdump-config  {  help  |  test | show | status | load | unload | savecore | propagate | symlinks {kernel-
             version} }

DESCRIPTION

       kdump-config manages the kdump feature of the Linux kernel.  When  a  kdump  enabled  kernel  panics,  it
       immediately  boots  into a clean kernel called the kdump kernel.  The memory image of the panicked kernel
       will be presented in /proc/vmcore while the kdump kernel (or "capture kernel") is running.

       kdump-config loads the kdump kernel into the current kernel and after a kdump, captures the vmcore  image
       via  kdump  kernel.   kdump-config can take advantage of the linux-image-$(uname -r)-dbg package and will
       try to use makedumpfile to capture the vmcore.  The crash tool can then be used to analyze the vmcore  at
       a later time.

       kdump-config exits with 0 on success and 1 on failure.

COMMANDS

       help   Print a usage summary.

       test   Determine  the  parameters  that would be used to load the kdump kernel, but do not load the kdump
              kernel.  Useful for evaluating your configuration settings.

       show   Show current parameters and the saved kexec command from the last kdump-config load.

       status Evaluate /sys/kernel/kexec_crash_loaded or /sys/kernel/fadump_register depending on the dump  mode
              and print a corresponding message.

       load   Load the kdump kernel or register if using firmware assisted dump (fadump)

       unload Unload the kdump kernel or unregister if using firmware assisted dump (fadump)

       savecore
              If /proc/vmcore exists, save it using makedumpfile.

       propagate
              Sends public ssh key to remote host for passwordless connection

       symlinks {kernel-version}
              Verify  and create vmlinuz and initrd.img links in /var/lib/kdump according to the provided kernel
              version. If the target initrd.img file is absent, it will create it.

FILES

       /etc/init.d/kdump-tools
                      init script to automatically load a kdump kernel, or save a vmcore and reboot.

       /etc/default/kdump-tools
                      configuration file

       /var/crash/kernel_link
                      a link to the current debug kernel

       /var/crash/kexec_cmd
                      the last kexec_cmd executed by kdump-config

       /var/lib/kdump/vmlinuz
                      Symbolic link pointing to the current kernel file in /boot

       /var/lib/kdump/initrd.img
                      Symbolic link pointing to the initrd.img file with the current kernel version in /boot

DIAGNOSTICS

USE_KDUMP is not set or zero
The variable USE_KDUMP in the file /etc/default/kdump-tools
is 0. To use kdump, edit the file and change the value to 1.

kdump is not supported by this kernel
The file /sys/kernel/kexec_crash_loaded does not exist. This means that the currently running
kernel either was not configured to support kdump, or that a crashkernel= commandline parameter
was not used when the currently running kernel booted.

no crashkernel= parameter in the kernel cmdline
a crashkernel= commandline parameter was not used when the currently running kernel booted. You
will need to add a crashkernel= parameter to your /etc/lilo.conf, /etc/elilo.conf or grub
/boot/grub/menu.lst file and reboot, before kdump will work. See installed READMEs for
suggestions.

KDUMP_KERNEL does not exist: $KDUMP_KERNEL
A KDUMP_KERNEL was specified in /etc/default/kdump-tools, but it cannot be found.

KDUMP_INITRD does not exist: $KDUMP_INITRD
A KDUMP_INITRD was specified in /etc/default/kdump-tools, but it cannot be found.

no KDUMP_KERNEL in $KDUMP_DEFAULTS and
can't find a kdump package directory in /usr/lib
no kdump kernel could be found.

found a linux-kdump package in $KDUMP_PKG_DIR
but can't find a kdump kernel in $KDUMP_PKG_DIR
this indicates a broken linux-kdump package installation.

no kdump initrd image: $KDUMP_INITRD
an initrd will not be used
this indicates that although a kdump kernel was found, a corresponding initrd was not found.

kdump kernel relocation address does not match crashkernel= parameter
For non-relocatable architectures, the kdump kernel must be built with a predetermined start
address. This message indicates that the start address of the kdump kernel and the start address
in the crashkernel= parameter do not match.

failed to load kdump kernel
kexec reported that it could not load the kdump kernel.

failed to unload kdump kernel
kexec reported that it could not unload the kdump kernel. Run 'kexec -u' directly for more
detail.

makedumpfile failed, falling back to 'cp'
this message is printed if the kdump-tools init script attempts to save a /proc/vmcore file using
makedumpfile and the save fails.

failed to save vmcore in $KDUMP_STAMPDIR
this message indicates that makedumpfile and the fallback method of using cp has failed. This
usually occurs if pathnames are wrong or if the disk is full.

Invalid argument : missing kernel version
The symlinks command was used with a kernel version that is not installed on this server

Invalid symlink : {symbolic link}
The listed symbolic link is absent, broken or pointing to the wrong version

Cannot change symbolic links when kdump is loaded
The defined symbolic links are already in use. You must unload kdump before using the symlinks
command

Unable to locate kernel hook
The kdump-tools script responsible for the creation of smaller initrd.img files is absent from
/usr/kernel/postinst.d

Invalid kernel version : {kernel version}
The kernel version given to the symlinks command does not exist

fadump is not configured in this kernel.
The Firmware Assisted Dump (fadump) facility is not available on this platform

SSH and NFS cannot be defined concurrently
Both variables are defined in /etc/default/kdump-tools. You must choose one or the other as
configuration option.

Unable to mount remote NFS directory {directory}. Cannot save core
The remote NFS server does not authorize this server to mount the directory to save the crash
dump.

Unable to write to the remote NFS directory {directory}. Cannot save core
The remote NFS directory can be mounted but this server cannot write files to it.

makedumpfile --dump-dmesg failed. dmesg content will be unavailable
The command to capture the content of the dmesg buffer failed. It will not be available in the
crash directory

Unable to reach remote server {server}. No reason to continue
kdump-tools is configured for remote dump but the remote server cannot be reached.

makedumpfile scp failed. The vmcore file will not be available
The makedumpfile command was successful but the resulting file could not be copied over SSH to the
remote server.

Remote ssh dump is not configured. No reason to propagate"
The propagate command was used but kdump is not configured for remote dump.

AUTHOR

       Written by Terry Loftin <terry.loftin@hp.com> and Louis Bouchard <louis.bouchard@ubuntu.com>