[Bug 1828187] Re: ibm, dynamic-memory property not found while loading kexec kernel (4.18.0-18-generic)

[Mathew Hodson]

** Also affects: kexec-tools (Ubuntu Cosmic)
   Importance: Undecided
       Status: New

** Also affects: kexec-tools (Ubuntu Bionic)
   Importance: Undecided
       Status: New

** Changed in: kexec-tools (Ubuntu Bionic)
       Status: New => In Progress

** Changed in: kexec-tools (Ubuntu Cosmic)
       Status: New => In Progress

** Changed in: kexec-tools (Ubuntu)
       Status: In Progress => Fix Released

** Changed in: kexec-tools (Ubuntu Bionic)
   Importance: Undecided => High

** Changed in: kexec-tools (Ubuntu Cosmic)
   Importance: Undecided => High

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Title:
  ibm,dynamic-memory property not found while loading kexec kernel
  (4.18.0-18-generic)

Status in The Ubuntu-power-systems project:
  In Progress
Status in kexec-tools package in Ubuntu:
  Fix Released
Status in kexec-tools source package in Bionic:
  In Progress
Status in kexec-tools source package in Cosmic:
  In Progress

Bug description:
  For SRU:

  [Impact]

   * The ibm,dynamic-memory-v2 device tree property replaced the
  original ibm,dynamic-memory property. Since kexec-tools doesn't know
  to look for the "-v2" property yet, it fails to successfully parse the
  node using the new "-v2" property.

   * These changes enable the new "-v2" property to be successfully
  parsed from the node.

  [Test Case]

   * Load panic kernel or regular kernel with kexec command:

  kdump-config unload; kdump-config load

  OR

  kexec -l --append="`cat /proc/cmdline`"
  --initrd=/boot/initrd.img-`uname -r` /boot/vmlinux-`uname -r`

  * Expected result: kexec loads without any warning/error messages

  [Testing]

  These changes were tested by Hari with a positive result on a 4.18
  kernel for ppc64el.

  [Regression Potential]

  * Low. 
  * These changes exist in 'kexec-tools' for disco and onwards (these kernels are all >= 4.16 where the -v2 property was enabled). 
  * The Bionic edge and Cosmic kernels have support for the -v2 property since they are also >= 4.16.
  * The regular 4.15 Bionic kernel is the more interesting of the bunch in terms of regression potential since 4.15 is too early to have the -v2 property enabled. The changes introduced by this patch appear to only attempt "-v2" parsing if it was unable to parse the "-v1" node. The absence of the v1 node implies that the device tree is using the "v2" property. Since the "-v2" option is not enabled for the 4.15 kernel, if the "-v1" parsing fails, then the "-v2" parsing will certainly fail, and the code throws the same error condition is it did before the patch was applied anyway.

  Original bug description below.
  ---

  == Comment: #0 - Hari Krishna Bathini <hbathini at in.ibm.com> - 2019-05-07 13:37:51 ==
  ---Problem Description---
  On 4.18.0-18-generic kernel, kexec load command throws below traces:

  ---

  Regular kexec load:

  root at ubuntu:~# kexec -l --append="`cat /proc/cmdline`" --initrd=/boot/initrd.img-`uname -r` /boot/vmlinux-`uname -r`
  /proc/device-tree/ibm,dynamic-reconfiguration-memory/ibm,dynamic-memory: No such file or directory
  Modified cmdline:BOOT_IMAGE=/boot/vmlinux-4.18.0-18-generic root=UUID=1aa9458c-3974-4cb4-9ab3-9ee03c0f4e5e ro crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M at 128M
  root at ubuntu:~#
  ---

  KDump kernel load:

  root at ubuntu:~# kdump-config unload
   * unloaded kdump kernel
  root at ubuntu:~# kdump-config load
   * Creating symlink /var/lib/kdump/vmlinuz
   * Creating symlink /var/lib/kdump/initrd.img
  /proc/device-tree/ibm,dynamic-reconfiguration-memory/ibm,dynamic-memory: No such file or directory
  /proc/device-tree/ibm,dynamic-reconfiguration-memory/ibm,dynamic-memory: No such file or directory
  Modified cmdline:BOOT_IMAGE=/boot/vmlinux-4.18.0-18-generic root=UUID=1aa9458c-3974-4cb4-9ab3-9ee03c0f4e5e ro maxcpus=1 systemd.unit=kdump-tools-dump.service irqpoll noirqdistrib nousb elfcorehdr=158912K
   * loaded kdump kernel
  root at ubuntu:~#
  ---

  Contact Information = hbathini at in.ibm.com

  ---uname output---
  Linux ubuntu 4.18.0-18-generic #19~18.04.1-Ubuntu SMP Fri Apr 5 10:21:11 UTC 2019 ppc64le ppc64le ppc64le GNU/Linux

  ---Additional Hardware Info---
  na

  Machine Type = na

  ---Debugger---
  A debugger is not configured

  ---Steps to Reproduce---
   Load panic kernel or regular kernel with kexec command:

  kdump-config unload; kdump-config load

  OR

  kexec -l --append="`cat /proc/cmdline`"
  --initrd=/boot/initrd.img-`uname -r` /boot/vmlinux-`uname -r`

  Actual Result:
  DT files are not found while loading the kernel

  Expected result:
  kexec loads without any warning/error messages

  Userspace tool common name: kexec-tools

  The userspace tool has the following bit modes: 64-bit

  Userspace rpm: kexec-tools

  Userspace tool obtained from project website:  na

  *Additional Instructions for hbathini at in.ibm.com:
  -Attach ltrace and strace of userspace application.

  == Comment: #1 - Hari Krishna Bathini <hbathini at in.ibm.com> -
  2019-05-07 13:44:25 ==

  Since v4.16 kernel, ibm,dynamic-memory-v2 Device Tree Property is supported
  in the kernel. This leaves kexec-tools on ppc64le broken without the below
  fix patches:

  https://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git/commit/?id=c740fdb2048265551f77d3f0fe53b2fddc0c8489
  ("kexec: add a helper function to add ranges")

  https://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git/commit/?id=b10924a7da3ca48c04982cd23daf04882afb1a87
  ("kexec/ppc64: add support to parse ibm, dynamic-memory-v2 property")

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