linux-kernel - Re: [PATCH 1/3 v4] x86/kdump: always reserve the low 1MiB when the crashkernel option is specified

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Date:   Wed, 23 Oct 2019 09:43:16 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     lijiang <lijiang@...hat.com>
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        hpa@...or.com, x86@...nel.org, bhe@...hat.com, dyoung@...hat.com,
        jgross@...e.com, dhowells@...hat.com, Thomas.Lendacky@....com,
        ebiederm@...ssion.com, vgoyal@...hat.com, kexec@...ts.infradead.org
Subject: Re: [PATCH 1/3 v4] x86/kdump: always reserve the low 1MiB when the
 crashkernel option is specified

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.

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