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SubjectRe: [Patch 1/4][kernel][slimdump] Add new elf-note of type NT_NOCOREDUMP to capture slimdump
On Wed, Oct 05, 2011 at 12:00:38PM -0400, Valdis.Kletnieks@vt.edu wrote:
> On Wed, 05 Oct 2011 11:52:17 EDT, Vivek Goyal said:
>
> > I am assuming that basic MCE error messages are available in kernel log.
>
> They're not in the kernel log if it's an MCE that causes the kernel to declare
> a panic. There's some MCE's that you can retry the operation and continue, and
> some that you can get away with poisoning a page, killing the process, and rest
> of the system is OK. But some you really need to roll over and die because you
> can't guarantee kernel integrity anymore.
>
> And at that point, those messages are never gonna make it to syslogd and onto
> disk.

AFAICT, and for the sake of getting the MCE info, arguably one could
look for log_buf in the vmcore of the old kernel and try to find the
last lines in the kernel log ringbuffer. They should be the MCE error
information from the do_machine_check MCE handler.

This all assuming of course we've managed to dump vmcore successfully by
sidestepping the landmines :-).

--
Regards/Gruss,
Boris.


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