kdump-config(8) configure kdump, check status, or save a vmcore file


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



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.


Print a usage summary.
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 current parameters and the saved kexec command from the last kdump-config load.
Evaluate /sys/kernel/kexec_crash_loaded or /sys/kernel/fadump_register depending on the dump mode and print a corresponding message.
Load the kdump kernel or register if using firmware assisted dump (fadump)
Unload the kdump kernel or unregister if using firmware assisted dump (fadump)
If /proc/vmcore exists, save it using makedumpfile.
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.


init script to automatically load a kdump kernel, or save a vmcore and reboot.
configuration file
a link to the current debug kernel
the last kexec_cmd executed by kdump-config
Symbolic link pointing to the current kernel file in /boot
Symbolic link pointing to the initrd.img file with the current kernel version in /boot


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.
A KDUMP_KERNEL was specified in /etc/default/kdump-tools, but it cannot be found.
A KDUMP_INITRD was specified in /etc/default/kdump-tools, but it cannot be found.

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.


Written by Terry Loftin <[email protected]> and Louis Bouchard <[email protected]>