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[Andrew Cloke <andrew.cloke@xxxxxxxxxxxxx>]

** Also affects: ubuntu-power-systems
   Importance: Undecided
       Status: New

** Changed in: ubuntu-power-systems
   Importance: Undecided => High

** Tags added: triage-g

** Changed in: ubuntu-power-systems
     Assignee: (unassigned) => Manoj Iyer (manjo)

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https://bugs.launchpad.net/bugs/1778651

Title:
  Update documentation about crashkernel parameter reuse for fadump

Status in The Ubuntu-power-systems project:
  New
Status in ubuntu-docs package in Ubuntu:
  New

Bug description:
  == Comment: #0 - Hari Krishna Bathini <hbathini@xxxxxxxxxx> - 2018-06-26 00:47:43 ==
  ---Problem Description---
  Since kernel commit 11550dc0a00b ("powerpc/fadump: reuse crashkernel parameter
  for fadump memory reservation"), crashkernel parameter is used to reserve memory
  for fadump, as well. 
   
  Machine Type = na 
   
  ---Steps to Reproduce---
   Install a Ubuntu kernel that is based on kernel v4.12 or above, and use
  crashkernel instead of fadump_reserve_mem to specify the memory to be
  reserved for fadump 
   
  ---uname output---
  na
   
  ---Debugger---
  A debugger is not configured
   
  Contact Information = hbathini@xxxxxxxxxx

  == Comment: #2 - Hari Krishna Bathini <hbathini@xxxxxxxxxx> - 2018-06-26 01:16:50 ==
  The section *Firmware Assisted Dump* in
  https://wiki.ubuntu.com/ppc64el/Recommendations

  should not be listed under *Bare Metal* as fadump is not specific to bare-metal.
  In fact, it is NOT supported on bare-metal currently.,

  Please remove *Bare Metal* as section heading and update the section
  to look like the below:

  ---
  *Firmware Assisted Dump*

  Firmware Assisted Dump (fadump) is an alternative to kdump crash
  dumping mechanism, available in powerpc architecture. To understand
  how fadump works, please refer to the kernel documentation below:

      https://www.kernel.org/doc/Documentation/powerpc/firmware-
  assisted-dump.txt

  Three steps are needed to use fadump as the crash dumping mechanism. Firstly, enabling
  fadump by passing "fadump=on" to kernel. Secondly, reserving some memory for fadump.
  Thirdly, registering fadump by echo'ing 1 to /sys/kernel/fadump_registered.

  1. To enable fadump:

      Add "fadump=on" to GRUB_CMDLINE_LINUX in /etc/default/grub file.
      Rebuild grub config 

          # grub-mkconfig -o /boot/grub/grub.cfg

  2. To reserve memory for fadump:
   
      Add "fadump_reserve_mem=<mem>" to GRUB_CMDLINE_LINUX in /etc/default/grub file.
      Rebuild grub config 

          # grub-mkconfig -o /boot/grub/grub.cfg

      NOTE: For ubuntu kernel that is based on kernel v4.12 or above, use 'crashkernel='
            instead of 'fadump_reserve_mem=', to specify the memory to be reserved
            for fadump

  3. To register fadump:

      Reboot the system for steps 1 & 2 to take effect.

      kdump-tools, scripts and tools for automating kdump, is updated to make it
      fadump aware.

      When fadump is enabled, kdump-tools registers fadump as crash dumping mechanism,
      by echo'ing 1 to /sys/kernel/fadump_registered. For more help, see: 

          # kdump-config help

  NOTE: If fadump fails to collect dump with Out Of Memory error, spike up the memory
        reserved for firmware-assisted dump (See step2).
  ---

  Thanks
  Hari

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