Provided by: kdump-tools_1.3.7-2_all bug


       kdump-tools.conf - configuration file for the kdump-tools init script




       kdump-tools  manages  the  kdump  feature  of  the  Linux  kernel.  The
       /etc/default/kdump-tools file contains local configuration settings  of

       This  file  is  sourced  into  a shell script, so it's format should be
       consistent with shell scripting.


              Controls whether or not kdump-tools will take  any  action.   If
              not set or 0, the kdump-tools init script will not run.

              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.

              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.

              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.

              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.

              This  variable  specifies  a  command  to run if the vmcore save
              fails.  If not set, no special action is taken.

              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.

              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.

              Additional arguments to the kexec command used to load the kdump

              Normally,  the  current  kernel  commandline  is  obtained  from
              /proc/cmdline.  Set this variable to override /proc/cmdline.

              Additional arguments to append to the command line for the kdump
              kernel.  If not set, “irqpoll maxcpus=1 nousb” will be used.


       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

       2.     Kernel  Command line parameters - the kernel must be booted with
              a crashkernel= command line parameter.  Some example crashkernel
                  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

              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.

       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

              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.


       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:

       This option starts a shell if kdump-tools cannot save the vmcore file:
              KDUMP_FAIL_CMD="/bin/bash; reboot -f"


       /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


       See kdump-config(8) for explanations of various error messages.


       kdump-config(8),   kexec(8),   sysctl(8),   makedumpfile(8),  crash(8),


       Terry Loftin <>