--- name: "kdump-config" section: "8" platform: "linux" package: "kdump-tools" version: "1:1.10.7" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/kdump-config" --- # kdump-config(8) configure kdump, check status, or save a vmcore file ## 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. ## SEE ALSO */usr/share/doc/kdump-tools/README*\ */usr/share/doc/kdump-tools/README.Debian*\ [**kdump-tools**(5)](/kdump-tools/5.md), [**kexec**(8)](/kexec/8.md), [**crash**(8)](/crash/8.md), [**gdb**(1)](/gdb/1.md), [**makedumpfile**(8)](/makedumpfile/8.md) ## AUTHOR Written by Terry Loftin \ and Louis Bouchard \