linux-kernel - Re: [PATCH v6 00/14] kexec: introduce Kexec HandOver (KHO)

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Message-ID: <8a57310a-dc4c-4ba2-9bc3-a16bc88ee4c5@intel.com>
Date: Mon, 28 Apr 2025 15:19:43 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Changyuan Lyu <changyuanl@...gle.com>, linux-kernel@...r.kernel.org
Cc: akpm@...ux-foundation.org, anthony.yznaga@...cle.com, arnd@...db.de,
 ashish.kalra@....com, benh@...nel.crashing.org, bp@...en8.de,
 catalin.marinas@....com, corbet@....net, dave.hansen@...ux.intel.com,
 devicetree@...r.kernel.org, dwmw2@...radead.org, ebiederm@...ssion.com,
 graf@...zon.com, hpa@...or.com, jgowans@...zon.com,
 kexec@...ts.infradead.org, krzk@...nel.org,
 linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org,
 linux-mm@...ck.org, luto@...nel.org, mark.rutland@....com, mingo@...hat.com,
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 thomas.lendacky@....com, will@...nel.org, x86@...nel.org
Subject: Re: [PATCH v6 00/14] kexec: introduce Kexec HandOver (KHO)

On 4/10/25 22:37, Changyuan Lyu wrote:
> When the actual kexec happens, the fdt is part of the image
> set that we boot into. In addition, we keep "scratch regions" available
> for kexec: physically contiguous memory regions that are guaranteed to
> not have any memory that KHO would preserve.  The new kernel bootstraps
> itself using the scratch regions and sets all handed over memory as in use.
> When drivers initialize that support KHO, they introspect the fdt, restore
> preserved memory regions, and retrieve their states stored in the preserved
> memory.

It would be nice to have some bit of this blurb in the per-arch
changelogs. It's not clear what the scratch regions are and how they are
being used in the early boot code. Even a pointer over to the
Documentation/ would be appreciated.