linux-kernel - Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area reservation code

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Message-ID: <20160721091411.GB22986@gmail.com>
Date:	Thu, 21 Jul 2016 11:14:11 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Andy Lutomirski <luto@...nel.org>, x86@...nel.org,
	Mario Limonciello <mario_limonciello@...l.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area
 reservation code


* H. Peter Anvin <hpa@...or.com> wrote:

> We already reserve the first megabyte by default.  There is something really bizarre about this; the bug report simply doesn't seem to make any sense.

Btw., are you sure about this? We do reserve the first 64KB:

config X86_RESERVE_LOW
        int "Amount of low memory, in kilobytes, to reserve for the BIOS"
        default 64
        range 4 640
        ---help---
          Specify the amount of low memory to reserve for the BIOS.

But I cannot find the place that allocates the first 1MB.

Thanks,

	Ingo