Update documentation about crashkernel parameter reuse for fadump

Bug #1778651 reported by bugproxy
8
This bug affects 1 person
Affects Status Importance Assigned to Milestone
The Ubuntu-power-systems project
Fix Released
High
Manoj Iyer
Ubuntu
Fix Released
Undecided
Ubuntu on IBM Power Systems Bug Triage

Bug Description

== Comment: #0 - Hari Krishna Bathini <email address hidden> - 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 = <email address hidden>

== Comment: #2 - Hari Krishna Bathini <email address hidden> - 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

bugproxy (bugproxy)
tags: added: architecture-ppc64le bugnameltc-169217 severity-high targetmilestone-inin---
Changed in ubuntu:
assignee: nobody → Ubuntu on IBM Power Systems Bug Triage (ubuntu-power-triage)
affects: ubuntu → ubuntu-docs (Ubuntu)
Changed in ubuntu-power-systems:
importance: Undecided → High
tags: added: triage-g
Changed in ubuntu-power-systems:
assignee: nobody → Manoj Iyer (manjo)
Revision history for this message
Gunnar Hjalmarsson (gunnarhj) wrote :

The ubuntu-docs package installs part of the Ubuntu Desktop Guide, and is unrelated to this issue. Changing to generic Ubuntu for now.

affects: ubuntu-docs (Ubuntu) → ubuntu
Revision history for this message
Frank Heimes (fheimes) wrote :

Chanaged in wiki according to the above suggestion:
https://wiki.ubuntu.com/ppc64el/Recommendations#Firmware_Assisted_Dump

Hence changing to Fix Released.

Changed in ubuntu:
status: New → Fix Released
Changed in ubuntu-power-systems:
status: New → Fix Released
bugproxy (bugproxy)
tags: added: targetmilestone-inin16044
removed: targetmilestone-inin---
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