------- Comment From hbath...@in.ibm.com 2019-05-22 07:16 EDT-------
(In reply to comment #12)
[...]
> But I thought this rules were there by accident and the entries would be put
> under arch flags to avoid them for ppc64..

If that is too much to ask, I am fine with the current change.
The change works as expected..

Thanks
Hari

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https://bugs.launchpad.net/bugs/1828596

Title:
  kdump fails when crash is triggered after DLPAR cpu add operation

Status in The Ubuntu-power-systems project:
  Incomplete
Status in kexec-tools package in Ubuntu:
  Invalid
Status in makedumpfile package in Ubuntu:
  Incomplete

Bug description:
  == Comment: #0 - Hari Krishna Bathini - 2019-05-10 05:55:40 ==
  ---Problem Description---
  kdump fails when crash is triggered after CPU add operation.
   
  Machine Type = na 
   
  ---System Hang---
   Crashed in early boot process of kdump kernel after crash

  Had to issue system reset from HMC to reclaim
   
  ---Steps to Reproduce---
   1. Configure kdump.
  2. Add cpu from HMC.
  3. Trigger crash.
  4. Machine hangs after crash as below:

  ---
  [169250.213166] IPI complete
  [169250.234331] kexec: Starting switchover sequence.
  I'm in purgatory
                               --- STRUCK HERE ---
   
  ---uname output---
  na
   
  ---Debugger---
  A debugger is not configured

  == Comment: #1 - Hari Krishna Bathini  - 2019-05-10 05:56:46 ==
  The problem is, kexec udev rule to restart kdump-tools service - when a core 
is added,
  is not being triggered. The old DT created by kexec (before the core is added)
  is being used by KDump Kernel. So, when system crashes on a thread from
  the added core(s), KDump kernel is failing to get the 'boot_cpuid' and
  eventually failing to boot..

  == Comment: #2 - Hari Krishna Bathini - 2019-05-10 06:02:27 ==
  The udev rule when CPU is added is not triggered because ppc64 does not
  eject add/remove event when a CPU is hot added/removed. It only ejects
  online/offline event to user space when CPU is hot added/removed.

  So, the below udev rules are never triggered when needed:

  SUBSYSTEM=="cpu", ACTION=="add", PROGRAM="/bin/systemctl try-restart 
kdump-tools.service"
  SUBSYSTEM=="cpu", ACTION=="remove", PROGRAM="/bin/systemctl try-restart 
kdump-tools.service"

  Also, with how CPU hot add & remove are handled in ppc64, a udev trigger
  to reload kdump after CPU is hot removed is NOT necessary. So, fix the CPU
  hot add case by updating the udev rule and drop the udev rule meant for CPU
  hot remove in the kdump udev rules file:

  
  SUBSYSTEM=="cpu", ACTION=="online", PROGRAM="/bin/systemctl try-restart 
kdump-tools.service"

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