linux-kernel - Re: [PATCH v7 13/18] x86/e820: temporarily enable KHO scratch for memory below 1M

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Message-ID: <425b4cbc-d36c-42b6-9071-3e0afab91441@intel.com>
Date: Fri, 2 May 2025 11:39:29 -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,
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Subject: Re: [PATCH v7 13/18] x86/e820: temporarily enable KHO scratch for
 memory below 1M

On 5/1/25 15:54, Changyuan Lyu wrote:
> From: Alexander Graf <graf@...zon.com>
> 
> KHO kernels are special and use only scratch memory for memblock
> allocations, but memory below 1M is ignored by kernel after early boot
> and cannot be naturally marked as scratch.
> 
> To allow allocation of the real-mode trampoline and a few (if any) other
> very early allocations from below 1M forcibly mark the memory below 1M
> as scratch.
> 
> After real mode trampoline is allocated, clear that scratch marking.

It's much more clear now, thanks!

Acked-by: Dave Hansen <dave.hansen@...ux.intel.com>