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Subject: Re: [PATCH] powerpc: on crash, kexec'ed kernel needs all CPUs are
 online
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Laurent Vivier <lvivier@redhat.com>, David Gibson <dgibson@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        thuth@redhat.com
Date: Sat, 17 Oct 2015 07:33:53 +0530
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On Fri, 2015-10-16 at 09:57 +0200, Laurent Vivier wrote:
> For me the problem is: as these CPUs are offline, I guess the core has
> been switched to 1 thread per core, so the CPUs (1 to 7 for core 0)
> don't exist anymore, how can we return them to OPAL ?

Another option is to make the new kernel kick_cpu fallback, if it knows
it's coming as a crashdump, to sending IPIs.

We would need some sane way to catch the guys coming it at 0x100 and
route the to secondary start.

Cheers,
Ben.