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Date: Tue, 13 Oct 2020 14:53:03 +0200
From: Petr Tesarik <ptesarik@suse.cz>
Subject: Is OS_INFO_VMCOREINFO unimplemented?
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Hi all,

I've been looking into kernel crash dump analysis for some time now,
and I've noticed that none of my sample dumps for z/Architecture sets
OS_INFO_VMCOREINFO.

Commit 4857d4bbe9821c8d732cb84455e18e12b3d79add suggests that the
"os_info" structure should contain vmcoreinfo, but it seems that the
corresponding fields are always zero, and a quick grep for
OS_INFO_VMCOREINFO finds only code that tries to read this entry in the
panic kernel, but no code that would initialize it in the old (crashed)
kernel.

In short, the panic kernel always prints an informational message that
entry 0 is not available and falls back to get_vmcoreinfo_old().

Is this a bug, or is this interface used by a non-Linux operating
system that I'm not aware of?

TIA,
Petr Tesarik
SUSE HW Enablement

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