From email from Luis, 6 June, 2008:

Lana,

IBM folks just sent us a note on their tests with kdump. Jeff Burke also
gave us a few drops of his knowldge about this issue. The summary is
something along the lines of:


For those willing to use kdump / kexec:

* we provide a script called rt-setup-kdump, that comes with newer rt-setup
  versions, which creates a basic rhel-rt (MRG) compliant kdump setup. It uses
  rhel5.1 or rhel5.2 kernel as the kdump kernel.

* the MRG realtime kernel is not suited to be used as the kdump kernel,
  hence the decision to use rhel5 kernels.

* some machines, namely IBM's LS21, may show the following warning messages
  when booting the kdump kernel:

	irq 9: nobody cared (try booting with the "irqpoll" option) handlers:
	[<ffffffff811660a0>] (acpi_irq+0x0/0x1b)
	turning off IO-APIC fast mode.
	...

  This is noted on BZ#448715. Some systems just show the messages and and
  keep on booting. Other systems may freeze after displaying the messages.
  A known workaround is to add "acpi=noirq" as a boot parameter to the kdump
  kernel. This parameter should be used only when the messages above have been seen,
  because it may cause boot problems on systems not affected by the original issue.


Luis
-- [ Luis Claudio R. Goncalves Red Hat - Realtime Team ] [ Fingerprint: 4FDD
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