This is really a bug on the kernel, after and including 4.18.
This is due to a patch that we have been carrying since forever, and
when the involved code changed a lot from 4.15 to 4.18, the patch was
dropped, as it couldn't be easily fixed up.
Even before that happened, I tried to upstream the patch, resending it
to the mailing list, but PPC maintainers wanted something different. The
original author resent with some modifications, but maintainers wouldn't
still apply it. As far as I remember, that patchset doesn't apply
anymore after the referred changes.
I have tried to work on a different solution, considering the new code
base, but didn't have much time to get a working solution.
Cascardo.
** Also affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Also affects: kexec-tools (Ubuntu Disco)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Disco)
Importance: Undecided
Status: New
** Also affects: kexec-tools (Ubuntu Eoan)
Importance: Undecided
Assignee: Ubuntu on IBM Power Systems Bug Triage (ubuntu-power-triage)
Status: New
** Also affects: linux (Ubuntu Eoan)
Importance: Undecided
Status: New
** Also affects: kexec-tools (Ubuntu Cosmic)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Cosmic)
Importance: Undecided
Status: New
** Changed in: linux (Ubuntu Cosmic)
Importance: Undecided => High
** Changed in: linux (Ubuntu Disco)
Importance: Undecided => High
** Changed in: linux (Ubuntu Eoan)
Importance: Undecided => High
** Changed in: linux (Ubuntu Eoan)
Assignee: (unassigned) => Thadeu Lima de Souza Cascardo (cascardo)
** Changed in: linux (Ubuntu Disco)
Assignee: (unassigned) => Thadeu Lima de Souza Cascardo (cascardo)
** Changed in: linux (Ubuntu Cosmic)
Assignee: (unassigned) => Thadeu Lima de Souza Cascardo (cascardo)
** Changed in: linux (Ubuntu Cosmic)
Status: New => Confirmed
** Changed in: linux (Ubuntu Eoan)
Status: New => Confirmed
** Changed in: linux (Ubuntu Disco)
Status: New => Confirmed
** Changed in: kexec-tools (Ubuntu Eoan)
Status: New => Invalid
** Changed in: kexec-tools (Ubuntu Disco)
Status: New => Invalid
** Changed in: kexec-tools (Ubuntu Cosmic)
Status: New => Invalid
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https://bugs.launchpad.net/bugs/1828597
Title:
KDump boot fails with nr_cpus=1
Status in The Ubuntu-power-systems project:
New
Status in kexec-tools package in Ubuntu:
Invalid
Status in linux package in Ubuntu:
Confirmed
Status in kexec-tools source package in Cosmic:
Invalid
Status in linux source package in Cosmic:
Confirmed
Status in kexec-tools source package in Disco:
Invalid
Status in linux source package in Disco:
Confirmed
Status in kexec-tools source package in Eoan:
Invalid
Status in linux source package in Eoan:
Confirmed
Bug description:
== Comment: #0 - Hari Krishna Bathini - 2019-05-10 06:38:21 ==
---Problem Description---
kdump boots fails in some environments when nr_cpus=1 is passed
---uname output---
na
Machine Type = na
---Debugger---
A debugger is not configured
---Steps to Reproduce---
1. configure kdump
2. trigger crash on non-boot cpu
Expected result:
Capture dump and reboot
Actual result:
Hang in early kdump boot process after crash
Userspace tool common name: kdump-tools
The userspace tool has the following bit modes: 64-bit
Userspace rpm: kdump-tools
Userspace tool obtained from project website: na
== Comment: #1 - Hari Krishna Bathini - 2019-05-10 06:45:46 ==
Launchpad bug 1560552 added "nr_cpus=1" support on ppc64 though
this change never made it upstream as maintainer has a few apprehensions..
With 4.18 kernels, this change is dropped on Ubuntu kernels too.
With nr_cpus=1 support in kernel, kdump-tools was also updated to
use "nr_cpsu=1" by default instead of "maxcpus=1" (see launchpad
bug 1568952). This kdump-tools change has to be reverted to make
it consist with the kernel change. Note that "nr_cpus=1 change had
a issues in kdump guest environment even with "nr_cpus=1" support
for kdump in kernel. So, even not withstanding the kernel revert, it is
better to default to "maxcpus=1" on all kernel versions. So, please
revert the kdump-tools fix that went in with launchpad bug 1568952
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