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Date:   Wed, 2 Nov 2022 11:54:08 -0500
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Subject: Re: [PATCH v13 7/7] x86/crash: add x86 crash hotplug support
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To:     Borislav Petkov <bp@alien8.de>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        kexec@lists.infradead.org, ebiederm@xmission.com,
        dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com,
        tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com,
        hpa@zytor.com, nramas@linux.microsoft.com, thomas.lendacky@amd.com,
        robh@kernel.org, efault@gmx.de, rppt@kernel.org, david@redhat.com,
        sourabhjain@linux.ibm.com, konrad.wilk@oracle.com,
        boris.ostrovsky@oracle.com
References: <20221031193604.28779-1-eric.devolder@oracle.com>
 <20221031193604.28779-8-eric.devolder@oracle.com> <Y2A4TqyOaPYBu4Hk@zn.tnic>
 <1c11a429-b5a9-fb55-fbef-b49e760e2d1e@oracle.com> <Y2I3zQ9ZU+C9Kgf7@zn.tnic>
 <06ef6e4b-1f42-d50f-1328-4f82fb34dd4d@oracle.com> <Y2KYls/Ji5E+4kPP@zn.tnic>
From:   Eric DeVolder <eric.devolder@oracle.com>
In-Reply-To: <Y2KYls/Ji5E+4kPP@zn.tnic>
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On 11/2/22 11:19, Borislav Petkov wrote:
> On Wed, Nov 02, 2022 at 09:55:06AM -0500, Eric DeVolder wrote:
>>> "But on a plain simple laptop or workstation which has CPU hotplug,
>>> would it make sense for the crash ranges to get updated too when CPUs
>>> are offlined?
>>
>> Yes, it does.
> 
> Why?
> 

Technically the answer is no; cpu hotplug events are independent of memory hotplug events, but both 
are written into the elfcorehdr, so in reality yes... The elfcorehdr contains a single list of Phdrs 
describing CPUs and crash memory ranges; the entire list is re-written on a hotplug change.

Eric