kdump-config(8)

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 <[email protected]> and Louis Bouchard <[email protected]>