linux-kernel - Re: [PATCH 1/1] x86, e820: Remove direct mapping of reserved space for HT hole around 1TB

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Message-ID: <4E94D4E7.5010001@zytor.com>
Date:	Tue, 11 Oct 2011 16:44:39 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Jacob Shin <jacob.shin@....com>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
	x86@...nel.org, Yinghai Lu <yinghai@...nel.org>
Subject: Re: [PATCH 1/1] x86, e820: Remove direct mapping of reserved space
 for HT hole around 1TB

On 10/11/2011 03:09 PM, Jacob Shin wrote:
> The entire HT hole and also the unused address range before that hole
> need to be excluded from direct mapping. Otherwise speculative
> accesses to that reserved region can happen which cause machine
> checks.

BARF!

This is completely insane ad hockery when all that really should need to 
happen is marking the HT region RESERVED, which should be possible on 
any HT-equipped processor.

	-hpa

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