linux-kernel - Re: [RFC][PATCH] Randomize kernel base address on boot

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Message-ID: <4DE28E1E.60207@zytor.com>
Date:	Sun, 29 May 2011 11:19:10 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Dan Rosenberg <drosenberg@...curity.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Tony Luck <tony.luck@...il.com>,
	linux-kernel@...r.kernel.org, davej@...hat.com,
	kees.cook@...onical.com, davem@...emloft.net, eranian@...gle.com,
	adobriyan@...il.com, penberg@...nel.org,
	Arjan van de Ven <arjan@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Valdis.Kletnieks@...edu, pageexec@...email.hu
Subject: Re: [RFC][PATCH] Randomize kernel base address on boot

On 05/29/2011 05:47 AM, Ingo Molnar wrote:
> 
> Do you mean we'd not start at a 2MB boundary and thus would waste on 
> average an about 0.125 worth of huge-TLB cache entry?
> 
> That does not look like a very big issue to me - but maybe i'm 
> missing something and you mean something else.
> 

The problem is that because of the misalignment, and whatever falls on
the other side of that memory boundary we might end up having to
fracture the 2 MB page into 4K pages.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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