Provided by:
kdump-tools_1.3.7-2_all 
NAME
kdump-tools.conf - configuration file for the kdump-tools init script
SYNOPSIS
/etc/default/kdump-tools
DESCRIPTION
kdump-tools manages the kdump feature of the Linux kernel. The
/etc/default/kdump-tools file contains local configuration settings of
kdump.
This file is sourced into a shell script, so it's format should be
consistent with shell scripting.
OPTIONS
USE_KDUMP
Controls whether or not kdump-tools will take any action. If
not set or 0, the kdump-tools init script will not run.
KDUMP_SYSCTL
Controls when a panic occurs, using the sysctl(8) interface.
Each time a kdump kernel is loaded, "sysctl -w $KDUMP_SYSCTL" is
also executed, thus allowing the system adiminstrator to
maintain customizable conditions for a kdump. The contents of
this variable should be the "variable=value ..." portion of the
"sysctl -w" command. If not set, "kernel.panic_on_oops=1" will
be used. This feature can be disabled by setting
KDUMP_SYSCTL=" "
See sysctl(8) for more info.
KDUMP_KERNEL
A full pathname to a kdump kernel (the kernel that is kexec'd at
crash time in a reserved memory area, exposing the old kernel's
memory for dumping). If not set, kdump-config will use the boot
kernel as the kdump kernel if it is relocatable; otherwise you
must set KDUMP_KERNEL in order for kdump-tools to work.
KDUMP_INITRD
A full pathname to the kdump initrd (if used). If KDUMP_KERNEL
is set and KDUMP_INITRD is not set, a warning message will be
printed, and an initrd will not be used.
KDUMP_COREDIR
Full path to a directory where the vmcore will be saved. Date
stamped subdirectories are created each time a vmcore file is
processed. If not set, /var/crash will be used.
KDUMP_FAIL_CMD
This variable specifies a command to run if the vmcore save
fails. If not set, no special action is taken.
DEBUG_KERNEL
A debug version of the running kernel. If not set, kdump-config
will use /usr/lib/debug/vmlinux-$(uname-r) if it exists.
Otherwise, kdump will still work, but the dump will take longer
and will be much larger.
MAKEDUMP_ARGS
Extra arguments passed to makedumpfile(8). If not set, "-c -d
31" will be used. This tells makedumpfile to use compression,
and reduce the corefile to in-use kernel pages only. See
makedumpfile(8) for details.
KDUMP_KEXEC_ARGS
Additional arguments to the kexec command used to load the kdump
kernel.
KDUMP_CMDLINE
Normally, the current kernel commandline is obtained from
/proc/cmdline. Set this variable to override /proc/cmdline.
KDUMP_CMDLINE_APPEND
Additional arguments to append to the command line for the kdump
kernel. If not set, "irqpoll maxcpus=1 nousb" will be used.
USAGE
kdump-tools is as automated as can be at this point but there are some
prerequisites to using it. Additionally, some manual configuration is
still required.
Manual Configuration
1. USE_KDUMP is set to 0 by default. To enable kdump-tools, edit
the /etc/default/kdump-tools configuration file and set
USE_KDUMP=1.
2. Kernel Command line parameters - the kernel must be booted with
a crashkernel= command line parameter. Some example crashkernel
parameters:
ia64: crashkernel=384M
x86: crashkernel=128M
x86_64: crashkernel=256M
Some users may also want to add nmi_watchdog=1 on certain
systems. The nmi watchdog will cause the kernel to panic (and
kdump) if a system hang is detected.
The kernel command line parameter is generally set in one of
these files: /etc/default/grub, /boot/grub/menu.lst,
/etc/elilo.conf, or /etc/lilo.conf. If the command line
parameter is changed, a reboot is required in order for it to
take effect.
3. Architectural considerations
A) x86 && PAE && memory > 4 Gigabytes - use
KDUMP_KEXEC_ARGS="--elf64-core-headers"
B) x86 and x86_64 - Some systems can take advantage of the
nmi watchdog. Add nmi_watchdog=1 to the boot commandline
to turn on the watchdog. The nmi interrupt will call
panic if activated.
C) ia64 - Some systems may need KDUMP_KEXEC_ARGS="--noio".
Use this if the system hangs after a panic, but before
the kdump kernel begins to boot.
Prerequisites
1. Boot Kernel Configuration - The boot kernel must be configured
with CONFIG_KEXEC=y and, if it is also to be used as the kdump
kernel, CONFIG_CRASHDUMP=y.
For ia64, only makedumpfile level 1 will work if the memory
model selected is CONFIG_DISCONTIG. CONFIG_SPARSEMEM is
recommended instead.
2. Kdump Kernel Configuration - The kdump kernel must be relocated
or relocatable. ia64 is relocatable by default, but x86,
x86_64, and powerpc must be built with CONFIG_RELOCATABLE=y.
Other architectures may require a predermined start location via
CONFIG_PHYSICAL_START. If the boot kernel is relocatable,
kdump-tools will automatically use that kernel. Otherwise, a
relocatable or relocated kernel will need to be provided. The
kdump kernel can be specified in the /etc/default/kdump-tools
file. Set the KDUMP_KERNEL variable and if necessary the
KDUMP_INITRD variable to point to the provided kernel and its
initrd.
The kdump kernel must be configured with: CONFIG_CRASH_DUMP=y
3. Debug Kernel - An uncompressed debug kernel should be provided
in order for makedumpfile to process the vmcore file. Without a
debug kernel, the transfer process is reduced to using
"makedumpfile -c -d 1". If /usr/lib/debug/vmlinux-$(uname -r)
exists, kdump-tools will automatically use that kernel.
Otherwise, A) set DEBUG_KERNEL in /etc/default/kdump-tools to
point to a debug version of the currently booted kernel or B) do
without - makedumpfile will still work, but the dumpfile will be
larger and take longer to save to disk.
EXAMPLES
Also panic and kdump on oom:
KDUMP_SYSCTL="kernel.panic_on_oops=1 vm.panic_on_oom=1"
Use this option on x86 systems with PAE and more than 4 gig of memory:
KDUMP_KEXEC_ARGS="--elf64-core-headers"
This option starts a shell if kdump-tools cannot save the vmcore file:
KDUMP_FAIL_CMD="/bin/bash; reboot -f"
FILES
/etc/init.d/kdump-tools an init script to automatically load a kdump
kernel, or save a vmcore and reboot.
/etc/default/kdump-tools the 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
DIAGNOSTICS
See kdump-config(8) for explanations of various error messages.
SEE ALSO
/usr/share/doc/kdump-tools/README
/usr/share/doc/kdump-tools/README.Debian
kdump-config(8), kexec(8), sysctl(8), makedumpfile(8), crash(8),
gdb(1),
AUTHOR
Terry Loftin <terry.loftin@hp.com>