Bug 456613 - Please include patch for automatic kdump crashkernel offset detection
Summary: Please include patch for automatic kdump crashkernel offset detection
Alias: None
Product: Red Hat Enterprise MRG
Classification: Red Hat
Component: realtime-kernel
Version: 1.2
Hardware: x86_64
OS: All
Target Milestone: ---
: ---
Assignee: Luis Claudio R. Goncalves
QA Contact:
Depends On:
TreeView+ depends on / blocked
Reported: 2008-07-24 22:40 UTC by IBM Bug Proxy
Modified: 2009-06-29 17:49 UTC (History)
2 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2009-06-29 17:49:43 UTC
Target Upstream Version:

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
IBM Linux Technology Center 46663 0 None None None Never

Description IBM Bug Proxy 2008-07-24 22:40:35 UTC
=Comment: #0=================================================
JOSHUA A. TRIPLETT <josht@us.ibm.com> - 2008-07-22 16:07 EDT
To make kdump work, the main kernel must have memory reserved for the kdump
kernel.  It reserves this memory during the early boot process, based on the
"crashkernel" option in the kernel command line.  This option generally looks
similar to "crashkernel=128M@32M".  The first number specifies the amount of
memory to reserve, and the second number specifies the offset in physical memory
to reserve this at.  However, some values for the offset will cause kdump not to
work on some systems; for instance, some systems fail with
"crashkernel=128M@16M", but work with "crashkernel=128M@32M".  This makes it
difficult to provide a standard kdump configuration for all platforms, and
requires additional documentation to address.

Git commit 32105f7fd8faa7bc3d101dcc3eabc0ae1ac375a7 ("x86: find offset for
crashkernel reservation automatically") in mainline linux-2.6 fixes this
problem.  It allows a crashkernel parameter like "crashkernel=128M", without an
offset, and automatically detects a usable offset.  (This requires a relocatable
kdump kernel, which MRG currently uses.)

This patch appears non-invasive.  Including it would simplify kdump
configuration and documentation.  Please consider including it in future
versions of the MRG kernel, and updating rt-setup-kdump to remove the offset
from the crashkernel parameter.

=Comment: #1=================================================
JOSHUA A. TRIPLETT <josht@us.ibm.com> - 2008-07-24 12:47 EDT

Comment 1 IBM Bug Proxy 2009-06-29 15:10:39 UTC
------- Comment From sripathik@in.ibm.com 2009-06-29 11:02 EDT-------
Saw this patch in 2.6.29 based MRG kernels. So MRG got this patch automatically. We can close this bug.

------- Comment From sripathik@in.ibm.com 2009-06-29 11:02 EDT-------
To RH: We are closing this bug on IBM side.

Comment 2 Clark Williams 2009-06-29 17:49:43 UTC
closing as well

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