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Date:   Wed, 23 Oct 2019 09:43:16 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     lijiang <lijiang@redhat.com>
Cc:     linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
        hpa@zytor.com, x86@kernel.org, bhe@redhat.com, dyoung@redhat.com,
        jgross@suse.com, dhowells@redhat.com, Thomas.Lendacky@amd.com,
        ebiederm@xmission.com, vgoyal@redhat.com, kexec@lists.infradead.org
Subject: Re: [PATCH 1/3 v4] x86/kdump: always reserve the low 1MiB when the
 crashkernel option is specified
Message-ID: <20191023074316.GA16060@zn.tnic>
References: <20191017094347.20327-1-lijiang@redhat.com>
 <20191017094347.20327-2-lijiang@redhat.com>
 <20191022083015.GB31700@zn.tnic>
 <0e657965-6f97-84ce-e51d-42d4978c4d88@redhat.com>
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On Wed, Oct 23, 2019 at 01:23:33PM +0800, lijiang wrote:
> Kdump kernel will reuse the first 640k region because the real mode
> trampoline has to work in this area. When the vmcore is dumped, the
> old memory in this area may be accessed, therefore, kernel has to
> copy the contents of the first 640k area to a backup region so that
> kdump kernel can read the old memory from the backup area of the
> first 640k area, which is done in the purgatory().

That sounds better. :)

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette